Introduction Platelets are widely recognized for their role in hemostasis, but emerging research has revealed their critical function in immunity. These small, anucleate cells are not merely passive mediators of clot formation; they actively participate in immune surveillance, pathogen recognition, and inflammatory regulation. Their interactions with both the innate and adaptive immune systems highlight their versatility in host defense, while their role in wound healing underscores their importance in tissue regeneration. However, their contribution to disease pathology, particularly in infections, demonstrates the delicate balance they maintain between protection and immunopathology. Understanding platelet-immune interactions offers new insights into potential therapeutic targets for infectious diseases and inflammatory conditions. Platelets and Innate Immunity Platelets, often thought of solely as the cellular mediators of clot formation, play a crucial role in the body's innate immune response. These small, anucleate cells serve as frontline responders to vascular injury, rapidly detecting breaches in blood vessel integrity and initiating clotting. However, their role extends far beyond hemostasis; platelets are equipped with a diverse range of immune receptors and signaling molecules that allow them to interact directly with pathogens and immune cells. At sites of injury or infection, platelets engage specific receptors such as glycoprotein (GP) Ib-V-IX and GPIIbIIIa to adhere to damaged endothelial surfaces. Their ability to bind extracellular matrix proteins, such as von Willebrand factor and collagen, ensures rapid accumulation at injury sites. In response to activation, platelets release a variety of pro-inflammatory molecules, including ADP, thromboxane, and cytokines, which help recruit additional immune cells to the site of damage. In addition to their role in clot formation, platelets act as immune sentinels, detecting and responding to microbial invaders. They express an array of pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), which enable them to recognize pathogen-associated molecular patterns (PAMPs). For example, TLR4 allows platelets to detect lipopolysaccharide (LPS) from Gram-negative bacteria, priming neutrophils for a robust immune response. Similarly, TLR7 recognizes viral RNA, prompting platelets to release complement factor 3 (C3) and stimulate neutrophil extracellular trap (NET) formation, which aids in pathogen clearance. Beyond their direct interactions with pathogens, platelets facilitate immune cell recruitment and activation. They tether neutrophils and monocytes to the endothelium, fostering extravasation into tissues where they can combat infections. Platelet-derived high-mobility group box 1 (HMGB1) enhances neutrophil function in bacterial peritonitis, while platelet CD40L interacts with neutrophil CD40 to promote integrin activation and reactive oxygen species (ROS) production. These interactions demonstrate that platelets are not passive bystanders in immunity but active regulators of inflammatory responses. Platelets and Adaptive Immunity While innate immunity provides immediate, non-specific defense, adaptive immunity generates long-term, antigen-specific responses. Platelets play a critical role in bridging these two arms of immunity. They support antigen presentation, enhance T-cell function, and modulate antibody responses. Platelets facilitate antigen trafficking and presentation, a crucial step in adaptive immunity. They can bind opsonized pathogens via complement receptors and shuttle them to antigen-presenting dendritic cells (DCs) in lymphoid organs. This interaction is particularly important for infections such as Listeria monocytogenes , where platelet-mediated antigen delivery enhances protective immunity. Moreover, platelets interact directly with T cells through surface receptors like CD40L. This molecule, typically expressed by activated T cells, is also present on platelets and plays a key role in T-cell priming and differentiation. In viral infections, platelet CD40L enhances cytotoxic CD8+ T-cell responses, improving pathogen clearance. Additionally, platelets influence T-helper cell polarization, promoting Th2 and Th17 responses in fungal infections while fostering regulatory T-cell (Treg) expansion to prevent excessive inflammation. Antibody production is another domain where platelets exert influence. They contribute to immunoglobulin G (IgG)-mediated pathogen clearance by expressing FcγRIIA, a receptor that binds immune complexes and facilitates phagocytosis. This mechanism is central to diseases such as heparin-induced thrombocytopenia (HIT), where immune complexes trigger platelet activation and thrombosis. Platelets in Wound Healing Beyond their immune functions, platelets play a pivotal role in wound healing. Their granules contain a wealth of growth factors, including platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and transforming growth factor-beta (TGF-β). These molecules promote tissue regeneration by stimulating fibroblast proliferation, angiogenesis, and extracellular matrix remodeling. Platelets also contribute to inflammatory resolution, ensuring a controlled transition from immune activation to tissue repair. They produce pro-resolving mediators like maresin-1, which counteracts inflammation and promotes healing. Additionally, platelet-derived TGF-β supports the expansion of regulatory T cells, fostering an anti-inflammatory environment conducive to tissue repair. The ability of platelets to modulate inflammation and promote healing has led to therapeutic applications, such as platelet-rich plasma (PRP) therapy. PRP is used to accelerate wound closure in chronic ulcers and orthopedic injuries by harnessing the regenerative potential of platelet-derived factors. However, despite its clinical promise, further research is needed to optimize its efficacy and application. Platelets in Infectious Disease Platelets play a crucial role in various infectious diseases, both as protectors and contributors to immunopathology: Bacterial Infections: Promote immunothrombosis, trapping bacteria in microvascular clots to limit dissemination. In Escherichia coli  bacteremia, platelet-neutrophil aggregates enhance pathogen clearance but can also lead to microvascular dysfunction. In sepsis, excessive platelet activation contributes to disseminated intravascular coagulation (DIC), leading to multi-organ failure. Viral Infections: In dengue fever, platelet activation leads to thrombocytopenia and vascular leakage, worsening disease severity. In COVID-19, hyperactivated platelets contribute to thromboinflammation, increasing the risk of deep vein thrombosis and pulmonary embolism. Platelets may act as viral reservoirs, as seen with SARS-CoV-2 RNA detected in circulating platelets. Fungal Infections: In Candida albicans  infections, platelets detect fungal toxins and release immune-modulating molecules to support antifungal immunity. In invasive aspergillosis, excessive platelet activation contributes to pulmonary hemorrhage and worsened disease outcomes. Conclusion Platelets are far more than simple clotting cells; they are integral to immune defense, tissue repair, and disease pathogenesis. Their ability to detect pathogens, recruit immune cells, and regulate inflammation underscores their importance in both innate and adaptive immunity. However, their dual role in protection and pathology necessitates a nuanced approach to therapeutic intervention. By further elucidating platelet-immune interactions, we can harness their potential to develop novel treatments for infectious diseases, inflammatory disorders, and tissue regeneration.

When we think about platelets, we typically associate them with wound healing and clot formation. However, emerging research has revealed their complex role in cancer progression. Beyond their traditional role in hemostasis, platelets actively contribute to tumor growth, immune evasion, and metastasis. On the flip side, their unique properties make them a potential tool for delivering targeted cancer therapies. In this post, we’ll explore the dual nature of platelets in cancer, their interactions with natural killer (NK) cells, and how platelet-derived microvesicles (PMVs) may be both promising and problematic in oncology. Platelets Enhancing Tumor Growth and Metastasis Platelets support cancer progression in multiple ways, from enhancing primary tumor growth to facilitating metastasis. Within the tumor microenvironment, platelets release growth factors such as vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and transforming growth factor-beta (TGF-β), which promote angiogenesis, sustain tumor cell survival, and encourage immune evasion. Additionally, activated platelets contribute to tumor-associated inflammation, which further supports malignant transformation and metastasis. One of the most critical roles of platelets in cancer is their interaction with circulating tumor cells (CTCs). When CTCs enter the bloodstream, they face numerous challenges, including shear stress and immune surveillance. Platelets form protective cloaks around CTCs, shielding them from immune attack and promoting their adhesion to the vascular endothelium, facilitating extravasation and the establishment of metastatic lesions. Studies have demonstrated that platelet depletion significantly reduces metastatic spread, underscoring their pivotal role in tumor dissemination. Platelets and NK Cells: Allies or Adversaries? Natural killer (NK) cells are key players in the immune system’s response to tumors. Unlike T cells, which require antigen presentation, NK cells can directly recognize and eliminate malignant cells based on stress-induced ligands and the absence of self-HLA markers. Their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) also makes them crucial in cancer immunotherapy, particularly in monoclonal antibody treatments. However, platelets can act as an obstacle to NK cell function. When they interact with tumor cells, platelets transfer inhibitory ligands such as HLA class I molecules to the cancer cell surface. This makes tumors appear more like normal cells, reducing their visibility to NK cells. Platelets also release TGF-β, a potent immunosuppressive cytokine that inhibits NK cell activation, impairs their cytotoxic function, and promotes the differentiation of regulatory T cells, further dampening the immune response. The impact of platelet interactions on NK cell-based therapies is a growing area of concern. Many cancer treatments, including immune checkpoint inhibitors and NK cell infusions, rely on strong NK cell function to eradicate tumors. Understanding how platelets suppress NK cell activity could lead to novel strategies to enhance the efficacy of immunotherapies. Platelet-Based Drug Delivery: A Double-Edged Sword The same characteristics that make platelets effective in shielding CTCs can be leveraged for therapeutic purposes. Researchers have explored the use of platelets as vehicles for targeted drug delivery, taking advantage of their ability to home in on tumor sites and interact with CTCs in circulation. Since platelets naturally accumulate in the tumor microenvironment and bind to cancer cells, they can be loaded with chemotherapeutics or immunotherapeutic agents for localized drug release. For instance, studies have shown that platelets loaded with doxorubicin, a widely used chemotherapy drug, can effectively target and inhibit tumor cells while reducing systemic toxicity. Similarly, platelet membranes have been engineered to carry immune checkpoint inhibitors, such as anti-PD-1 antibodies, to the tumor site, enhancing the immune response against cancer. Despite these promising developments, challenges remain. Platelet-based drug delivery systems require optimization to ensure prolonged circulation time and controlled drug release. Additionally, the risk of platelet-induced clotting complications must be carefully considered, particularly in cancer patients who already have an elevated risk of thrombosis. Platelet Microvesicles (PMVs): Promise and Peril in Cancer Therapy Platelet-derived microvesicles (PMVs) are small extracellular vesicles released from activated platelets that carry bioactive molecules, including proteins, lipids, and RNA. PMVs play a critical role in intercellular communication and have been implicated in both tumor progression and immune modulation. Their ability to transport signaling molecules makes them an attractive candidate for drug delivery in cancer therapy. PMVs as Therapeutic Vehicles Similar to whole platelets, PMVs can be engineered to deliver chemotherapeutic agents or immunomodulatory molecules. Since they naturally interact with tumor cells and immune cells, PMVs could serve as highly specific carriers for anti-cancer drugs. One potential application is loading PMVs with immune-stimulating molecules to counteract the immunosuppressive effects of the tumor microenvironment. PMVs could also be modified to carry small interfering RNA (siRNA) or other genetic material to target oncogenic pathways directly. Potential Risks of PMVs in Cancer Patients While the therapeutic potential of PMVs is exciting, their use in cancer patients is not without risks. PMVs have been shown to play a role in cancer-associated thrombosis, which is a major cause of morbidity and mortality in oncology patients. Their pro-coagulant properties, largely due to the presence of phosphatidylserine and tissue factor, can contribute to excessive clot formation, increasing the risk of venous thromboembolism (VTE). Moreover, PMVs may inadvertently promote tumor progression. Studies suggest that PMVs can facilitate tumor cell invasion, angiogenesis, and immune suppression—similar to intact platelets. The exact mechanisms underlying these effects remain unclear, and further research is needed to determine whether PMVs can be safely used in cancer therapy without exacerbating disease progression. Another unknown is how PMV-based therapies would interact with existing treatments. Would they interfere with immune checkpoint inhibitors or chemotherapy? Could they enhance or mitigate the effects of platelet transfusions in cancer patients? These questions highlight the need for rigorous preclinical and clinical studies before PMVs can be safely integrated into oncology treatment strategies. Conclusion: Harnessing Platelets Without Empowering Cancer The dual nature of platelets in cancer presents both challenges and opportunities. On one hand, they actively promote tumor growth, metastasis, and immune evasion. On the other, their natural tumor-homing abilities and bioactive vesicles offer innovative pathways for drug delivery and therapeutic intervention. Future research must focus on disentangling the beneficial from the harmful aspects of platelet function in cancer. Strategies that selectively inhibit platelet-mediated tumor protection without compromising hemostasis could significantly improve the efficacy of existing therapies. Additionally, the potential of platelet-derived microvesicles in oncology should be approached with caution, ensuring that their application does not inadvertently fuel cancer progression. Platelets in Oncology: Friend, Foe, or Future Therapy? As our understanding of platelets in cancer deepens, we move closer to a future where these cellular fragments are not just accomplices in malignancy but allies in its defeat.

Wound healing is a finely tuned biological process that relies on multiple cellular and molecular mechanisms to restore damaged tissue. Among the key players in this process are platelets—anucleate cell fragments primarily known for their role in hemostasis. However, beyond clot formation, platelets and their derived microvesicles play a crucial role in promoting tissue regeneration, modulating inflammation, and facilitating cell recruitment. Recent advances in biomaterial science, particularly the development of hydrogels, have expanded the potential of platelet-derived therapies in wound healing. In this post, we explore the molecular mechanisms behind platelet-mediated wound healing, the role of platelet microvesicles, and how hydrogels are revolutionizing the delivery of platelet-derived factors in clinical applications. The Molecular Mechanisms of Platelet-Mediated Wound Healing The wound healing process occurs in distinct but overlapping phases: hemostasis, inflammation, proliferation, and remodeling. Platelets initiate this process by adhering to exposed extracellular matrix components at the site of injury. This adhesion is mediated by key receptors such as glycoprotein Ib and integrin αIIbβ3, which interact with von Willebrand factor and fibrinogen, respectively. Once activated, platelets release a plethora of growth factors and cytokines from their alpha and dense granules. Among these signaling molecules, platelet-derived growth factor (PDGF) promotes fibroblast proliferation and extracellular matrix deposition, while vascular endothelial growth factor (VEGF) enhances angiogenesis by stimulating endothelial cell migration and capillary formation. Additionally, transforming growth factor-beta (TGF-β) plays a crucial role in modulating immune responses and promoting extracellular matrix synthesis. Platelets also contribute to wound contraction by forming a provisional fibrin scaffold that serves as a matrix for cell migration. Their ability to interact with leukocytes further amplifies the immune response, ensuring that pathogens and necrotic debris are efficiently cleared from the wound environment. By orchestrating these cellular interactions, platelets create an optimal microenvironment for tissue repair. Platelet-Derived Microvesicles: Tiny but Mighty Beyond their direct role in hemostasis and growth factor secretion, platelets release extracellular vesicles, particularly platelet-derived microvesicles (PMVs), which serve as potent mediators of intercellular communication. These microvesicles are rich in bioactive molecules, including cytokines, lipids, and microRNAs, which influence various aspects of wound healing. PMVs interact with endothelial cells, fibroblasts, and immune cells, delivering molecular cargo that enhances cell proliferation, migration, and differentiation. One of the most intriguing aspects of PMVs is their ability to modulate immune responses. They interact with neutrophils and macrophages, influencing their polarization toward pro-healing phenotypes. Additionally, PMVs contribute to the resolution of inflammation, thereby preventing excessive tissue damage and promoting a more balanced healing process. Their ability to transfer microRNAs further underscores their importance in regulating gene expression in recipient cells, making them a promising target for therapeutic applications in chronic wounds and tissue regeneration. Hydrogels: A Novel Delivery System for Platelet-Derived Therapies Despite the promising potential of platelet-derived therapies, one of the challenges in clinical application is ensuring sustained and controlled delivery of bioactive factors to the wound site. Hydrogels, three-dimensional polymeric networks with high water content, have emerged as an innovative solution for this challenge. These biomaterials provide a supportive scaffold for cell attachment and proliferation while allowing for the controlled release of growth factors and extracellular vesicles over time. Hydrogels can be designed to mimic the natural extracellular matrix, improving their compatibility with biological tissues. They can be engineered with specific physical and biochemical properties to optimize platelet-derived factor delivery. Thermosensitive hydrogels, for example, remain in liquid form at lower temperatures but gel upon contact with body temperature, ensuring targeted application. Additionally, hydrogels loaded with platelet-derived extracellular vesicles or exosomes enhance their stability and prolong their bioactivity, thereby maximizing their therapeutic efficacy. In wound healing applications, platelet-derived exosomes encapsulated in hydrogels have been shown to accelerate tissue repair, particularly in diabetic ulcers and chronic wounds. These hydrogels not only protect exosomes from rapid degradation but also facilitate their localized release, allowing for sustained cellular interactions and tissue regeneration. Clinical Applications of Platelet-Derived Therapies in Wound Healing Platelet-rich plasma (PRP) and platelet-derived fibrin (PRF) have been extensively studied for their ability to enhance wound healing in clinical settings. PRP, a concentrate of platelets suspended in plasma, has been used in the treatment of chronic ulcers, surgical wounds, and burns. By delivering high concentrations of growth factors directly to the wound site, PRP accelerates tissue repair and reduces healing time. Similarly, PRF, a fibrin-based matrix rich in platelets and leukocytes, provides a sustained release of bioactive molecules and is commonly used in oral and maxillofacial surgery. Recent clinical studies have explored the application of platelet-derived extracellular vesicles in regenerative medicine. For example, hydrogel-based delivery of platelet-derived exosomes has demonstrated promising results in enhancing wound closure, angiogenesis, and collagen deposition. Studies in diabetic wound models have shown that exosome-loaded hydrogels significantly improve healing outcomes by promoting granulation tissue formation and reducing inflammation. Moreover, in orthopedic and reconstructive surgery, platelet-derived exosomes have been used to enhance bone and soft tissue regeneration, further expanding their potential applications. The source of platelets used in these therapies can be either autologous or allogeneic. Autologous platelet-derived therapies are derived from the patient’s own blood, reducing the risk of immune reactions and transmission of infections. However, autologous PRP may exhibit variability in composition based on patient health and platelet count. Allogeneic platelet-derived products, obtained from donor blood, offer a more standardized and readily available option, particularly for patients with low platelet counts or conditions that prevent autologous blood collection. Although allogeneic platelet products must undergo rigorous screening to ensure safety and efficacy, they present an attractive alternative for broad clinical application. Conclusion As research advances, the integration of platelet-derived therapies with biomaterials such as hydrogels holds immense promise for the future of regenerative medicine. By harnessing the natural regenerative capacity of platelets and optimizing their delivery through innovative biomaterials, we can revolutionize the treatment of chronic wounds and tissue injuries, ultimately improving patient outcomes and quality of life. The continued development of standardized platelet preparation methods, along with improved biomaterial engineering, will be crucial in refining these therapies for widespread clinical use. Furthermore, expanding research into platelet-derived microvesicles and their role in tissue repair may unlock new therapeutic strategies for previously untreatable wounds and degenerative conditions. By bridging the gap between fundamental biology and applied medicine, platelet-derived therapies may soon become a cornerstone of advanced wound healing and regenerative treatments, offering hope to millions of patients worldwide.

Galveston, Texas is a picturesque city located on an island in the Gulf of Mexico. The sandy beaches and warm waters have long attracted visitors, and the population of the city swells every summer with approximately forty thousand additional souls at any given time. Events and festivals draw in even more, with upwards of one hundred thousand visitors over the course of a weekend.   Of course, more people on the island means more traffic in the local emergency departments, including more trauma activations, more admissions, and the utilization of more resources like blood products. The people working in healthcare are aware of this, with superstitious trepidation assigned to one event in particular – the Lonestar Biker Rally, locally known as Biker Weekend.   Occurring every October, the Biker Weekend brings an estimated one hundred thousand motorcycle enthusiasts to Galveston for four days of festivities. Recent years have featured high-profile, fatal, motorcycle accidents and even shootings, making Biker Weekend one of the most feared calls for local healthcare workers. Out of this fear comes rumors – that Biker Weekend has the highest rate of mortality in the hospital, that Biker Weekend features the most trauma codes, and that Biker Weekend uses the most blood products of any weekend in the year.   While I can’t address all these superstitions, together with my colleagues Dr. Sri Bharathi Kavuri, Dr. John Broussard, and Ms. Ashlie Atchison, I looked into whether Biker Weekend does indeed use an abnormally high number of blood products.   The first step was to choose an appropriate control for our hypothesis that would address confounding variables. While the activities during Biker Weekend, with their mix of motorcycles, alcohol, and sometimes violence, certainly appear to have more potential for danger, trauma, and blood usage, we would need to control for the effect of increased population. To do this, we would need to select a comparison event with a similar population increase but without the same potential hazards, and eventually chose Memorial Day Weekend as an appropriate comparison.   Next, we pulled the total number of each blood product type dispensed over either Memorial Day Weekend or Biker Weekend over the past five years, from 2018 to 2023. In 2020 no Lonestar Biker Rally was held due to concerns over the pandemic, so for both events the year 2020 was omitted. Finally, we pulled the total number of Massive Transfusion Protocols, or MTPs, which are defined as the transfusion of 10 or more packed red blood cells. MTPs are typically seen in cases of massive hemorrhage such as a traumatic accident.   Comparing the type and total blood products dispensed over the two weekends from 2018 to 2023 (and omitting the year 2020), we see no statistically significant difference. This includes packed red blood cells (RBC), fresh frozen plasma (FFP), platelets, and cryo. There is a trend towards transfusion of greater numbers of FFP units during Biker Weekend (P=0.11), but more data would be needed to properly assess this. We did find a trend towards a higher number of MTPs on Biker Weekend, although the difference was not quite statistically significant from this data set (P=0.078). Tracking the number of MTPs for the past 5 years indicates that MTPs during Biker Weekend are increasing over time. However, tracking the number of MTPs during both events for the next several years will be needed to firmly determine whether there is indeed a higher number of MTPs on Biker Weekend. We cannot conclude that Biker Weekend involves the utilization of more blood products. The data suggest the opposite – that Biker Weekend uses the same total blood products as other very populous events on Galveston Island.   However, how   blood products are dispensed from the blood bank may very well be different. With more data over time, we may see that Biker Weekend features fewer patients needing massive amounts of blood, whereas other events feature more patients needing less support from blood products. Moreover, this pattern may not be apparent from simply looking at totals of blood product usage, which in this data set are no different.   Did we dispel the rumor that Biker Weekend uses more blood? I think the answer involves some nuance, as is often the case. Certainly, there are other aspects of Biker Weekend we did not track, such as trauma code activations, mortality, or trauma admissions, and this would be required to have a thorough understanding of the impact of Biker Weekend on local healthcare resources.   I think we can say that the truth is more complicated than the superstitions surrounding Biker Weekend. However, this will likely not stop surgery residents from arm wrestling over who has to take call when the Lonestar Rally comes to town.

Medical training is often framed as a journey of relentless personal responsibility. Trainees are expected to learn from manuals, absorb literature, and independently synthesize vast amounts of information. But I didn’t come here just to learn from textbooks. I came to be trained by world-class experts and, most importantly, by the patients I serve. There is an unspoken rule in medical education: success is almost entirely the responsibility of the trainee. If a trainee thrives, it is attributed to their hard work and dedication. If they struggle, the burden of that struggle is placed squarely on their shoulders. Over the years, I’ve seen this model play out again and again. It suggests that success is 95% the trainee’s responsibility and only 5% the responsibility of their supervisors, mentors, and the system itself. I understand why this idea is appealing. It creates a convenient narrative: mentors can celebrate a successful trainee while distancing themselves from one who falters. But from my own experience, and from years of observing the journeys of my colleagues, I have come to a different conclusion. The truth is that success in medical training is not a solitary pursuit—it is a shared endeavor. The balance is closer to 50/50. This is not to say that trainees bear no responsibility for their learning. Of course we do. We must show up prepared, ask thoughtful questions, engage in critical thinking, and put in hours of study and practice. But training does not happen in a vacuum. Mentorship matters. Guidance matters. The environment in which we train—the culture, the expectations, the support—matters. When these elements are lacking, even the most determined and capable trainee will struggle. There is an illusion in medical training that the best way to learn is to figure things out on your own. That if you are truly dedicated, you will spend every spare moment combing through the literature, searching for answers in isolation. But I have found that this is often an inefficient, and sometimes even ineffective, way to learn. Expertise is not just about knowledge; it is about the ability to distill, to interpret, to teach. A well-placed question, asked at the right moment, can unlock understanding in a way that hours of solo study cannot. And yet, the culture of medicine does not always encourage this kind of active engagement. Some trainees hesitate to ask questions for fear of looking unprepared. Some supervisors expect trainees to “figure it out” without recognizing the inefficiency of that approach. But mentorship is not about making learning harder—it is about making it richer. The best mentors understand this. They do not see a trainee’s questions as a burden, but as an opportunity to guide, to shape, to share their hard-won wisdom in a way that truly makes a difference. My own path through medical training has not followed the standard script. I am not a fresh-faced twenty-something with no external responsibilities and a financial safety net. I work multiple jobs to afford the privilege of being here. My time is not infinite, and my ability to learn is not enhanced by exhaustion or financial stress. For someone like me, efficiency in learning is not a luxury—it is a necessity. Asking direct questions, seeking clarification, and engaging in real-time discussions with my mentors is not about cutting corners. It is about making the most of the time and resources available. And isn’t that what training is supposed to be? Not an endurance test, but an experience that equips us with the skills, knowledge, and confidence to become the best physicians we can be? If we want to train the next generation of great doctors, we need to rethink the way we approach medical education. We need to recognize that success is not the result of solitary struggle, but of meaningful mentorship and shared responsibility. We need to create an environment where trainees feel supported, where their time is valued, and where learning is seen as a collaborative process rather than an individual burden. Because in the end, the measure of a great training program is not just the excellence of its trainees, but the quality of the mentorship that shapes them.

When people think of pathology informatics, they often imagine cutting-edge artificial intelligence, whole-slide imaging, or complex algorithms identifying patterns in tumor cells. But the real backbone of pathology informatics—the work that ensures patient data moves seamlessly between systems, institutions, and even countries—is much less glamorous. Interoperability and standardization of data aren’t flashy topics, but they’re critical to modern healthcare. Without them, even the most advanced AI tools or digital pathology systems become isolated silos of information, limiting their clinical utility. Why Does Interoperability Matter in Pathology? Pathology is inherently a data-heavy field. Every biopsy, blood test, or molecular assay generates structured (numerical values, test results) and unstructured (pathology reports, images) data. This data must be: Accessible  across different electronic health record (EHR) systems Consistently formatted  so it can be analyzed and compared Integrated  with clinical decision-making tools Yet, pathology informatics is plagued by a lack of true interoperability. Many laboratories use proprietary information systems that don’t communicate well with others. As a result, sending a patient’s pathology report from Hospital A to Hospital B can still involve fax machines, PDFs, and manual data entry—archaic processes that increase the risk of errors and delays. Case in Point: The Molecular Pathology Report Bottleneck Consider a patient with non-small cell lung cancer (NSCLC) undergoing molecular testing for targeted therapy selection. A next-generation sequencing (NGS) test performed at one institution might identify an actionable EGFR mutation, but if the patient transfers care to another hospital, that genetic data might not integrate into their new oncologist’s system. Why? Because molecular pathology reports are often embedded in PDFs rather than structured formats, making it nearly impossible for EHR systems to extract and analyze key mutations automatically. This means oncologists may need to manually review and re-enter data, risking transcription errors and delays in treatment. The Challenge of Standardization Even when data is shared, inconsistency in formatting can be a nightmare. Different labs may use different naming conventions, reference ranges, or units for the same test. A simple example: One lab reports serum creatinine  as 1.2 mg/dL , while another expresses it as 106 µmol/L —same result, different units. A molecular lab may report BRAF V600E , while another might write c.1799T>A —same mutation, different notation. These discrepancies create unnecessary hurdles for automated clinical decision support (CDS) tools, which rely on standardized inputs to provide actionable recommendations. HL7, FHIR, and Other Efforts—Not a Magic Fix Efforts like HL7 (Health Level Seven)  and FHIR (Fast Healthcare Interoperability Resources)  aim to create universal standards for exchanging healthcare data. While they’ve improved interoperability in some areas, pathology data remains particularly challenging due to its complexity. For instance, the CAP Cancer Protocols  provide standardized pathology report templates, but implementation is inconsistent. LOINC (Logical Observation Identifiers Names and Codes)  standardizes lab test names, yet many labs don’t map tests correctly. Similarly, SNOMED CT (Systematized Nomenclature of Medicine—Clinical Terms)  provides standardized codes for diagnoses and laboratory findings, ensuring consistency across systems. However, its adoption remains uneven, limiting its full potential for interoperability. Real-World Consequences Poor interoperability and data standardization aren’t just IT headaches—they have real-world implications: Delayed Diagnoses  – A patient’s lab results might be trapped in a system that doesn’t communicate with a specialist’s platform. Increased Costs  – Redundant testing happens because prior results are inaccessible. Compromised Research  – Large-scale studies depend on harmonized datasets, but inconsistent formats make data aggregation difficult. Where Do We Go from Here? Push for Structured Data  – Pathology reports should be machine-readable, not just PDFs. Standardized synoptic reporting should become the norm. Expand Use of Interoperability Standards  – Labs must actively adopt HL7 FHIR, LOINC, and SNOMED CT coding in a meaningful way. Advocate for Vendor Collaboration  – Laboratory information system (LIS) vendors should prioritize interoperability instead of locking customers into proprietary ecosystems. The work of making pathology data flow seamlessly across systems may not be as exciting as AI-driven diagnostics, but without it, the future of precision medicine remains stuck in the past.

Introduction CAR-T cell therapy has revolutionized the treatment of hematological cancers by harnessing the power of the immune system to specifically target and destroy malignant cells. This innovative approach involves modifying T-cells to express chimeric antigen receptors (CARs), which enable precise antigen recognition and potent immune activation. While initially developed to combat hematologic malignancies like leukemia and lymphoma, the therapeutic potential of CAR-T cells has expanded significantly. Researchers are now exploring its application in diverse areas, including autoimmune diseases and solid tumors, paving the way for novel treatment paradigms. In this article, we delve into the foundational mechanisms of CAR-T therapy and its evolving applications. From the sources of T-cells to cutting-edge genetic engineering techniques, we explore how advances in technology are optimizing the efficacy and safety of CAR-T cells. The article also examines how this approach is transforming the management of autoimmune disorders by offering a targeted, immune-resetting solution. Finally, we discuss the unique challenges posed by solid tumors and the innovative strategies being developed to overcome them. Together, these insights highlight the vast potential of CAR-T therapy to address some of the most challenging conditions in medicine today. Genetic Modification of T-Cells CAR-T cell therapy involves genetically modifying T-cells to recognize and destroy specific targets. Modified T-cells express a CAR which combines the extracellular domain of an antibody with the intracellular domain of a T-cell receptor along with a co-stimulatory molecule. Thus, the finely tunable antigen recognition of an antibody is coupled to T-cell activation, which results in destruction of the target. The expression of CAR constructs involves introduction of a larger amount of genetic code, and for this purpose lentiviral vectors are often used because they carry a large payload (~10kb). The benefits of lentiviral vectors include integration into the genome and stable expression of the CAR construct. Moreover, lentiviral vectors can integrate into many cell types, including non-dividing cells. However, integration into the genome will be random and may result in insertional oncogenesis, whereby the vector itself increases cancer risk. Typically, manufactured T-cells are screened for lentiviral copy number at the end of manufacturing, with a copy number ≥ 5/cell indicating increased risk for oncogenesis. Recent studies are pioneering the use of CRISPR editing in CAR-T cells to reduce therapy risks and enhance performance. CRISPR gene editing involves creating a double-stranded break at a specific sequence, which can then be used to either disrupt expression of a gene (“knock-out”) or edit the gene itself. In CAR-T cell therapies, CRISPR is being used to knock out the cell’s endogenous T-cell receptor to reduce risk of GvHD, the cell’s expression of MHC molecules to reduce risk of graft rejection and failure, and inhibitory regulators of T-cells to enhance function. There is also ongoing research into using the CRISPR system to insert the CAR construct itself into specific places in the genome, which avoids the inherent insertional oncogenesis risk of lentiviral vectors. Sources of T-Cells Currently, the gold standard for CAR-T cell therapy is collection of cells outside the body, followed by genetic manipulation in a lab, and finally infusion of the modified cells back into the patient. For this process, different sources of T-cells are used, with each approach offering distinct advantages and challenges. Autologous CAR-T Cells : Derived from the patient’s own T-cells, these therapies pose a lower risk of graft-versus-host disease (GvHD) and graft failure from immune rejection. These therapies also have a higher chance of long-term persistence, allowing for potential surveillance and destruction should the target return. Their longer lifespan makes them an ideal source for cancer treatments. Manufacturing challenges can arise due to the compromised quality of T-cells in patients with advanced diseases, and the bespoke nature of individualized therapies. However, as the longest utilized source of T-cells for CAR-T cell therapy, autologous cells have the most validated manufacturing protocols. Allogeneic CAR-T Cells : Derived from healthy donors, these cells are hardier and easier to genetically modify. Moreover, one collection from one donor can be used to treat multiple patients. In this way, allogeneic CAR-T cells act as an ‘off-the-shelf’ cellular therapy. Despite these advantages, they carry a higher risk of graft failure via immune rejection and GvHD. They are also less likely to persist in the body over time, and may require multiple doses to achieve a therapeutic effect. Finally, as a newer technology, allogeneic CAR-T cells have less history behind them and need further study and validation. In-Vivo CAR-T Cells : Finally, the newest ‘source’ of CAR-T cells doesn’t involve collecting cells outside a body at all. Cutting edge clinical trials are underway to test the idea that CAR-T cells can be ‘manufactured’ inside the body. This approach hinges on the use of gene vector that specifically targets a subset of cells. A large portion of ‘in-vivo’ CAR-T cell trials are using vectors based on the lentivirus backbone, which has been engineered to express an antibody-based cell targeting moiety, as well as various glycoproteins from other viral families to enhance uptake into the desired cell subset. However, other gene vectors - such as lipid nanoparticles - are being tested, with the most effective strategy yet to be determined. CAR-T Therapy in Autoimmune Disorders CAR-T cell therapies are rapidly gaining attention as a groundbreaking approach to treating autoimmune diseases by directly addressing the immune system abnormalities driving these conditions. Traditionally developed for cancer, CAR-T cells have been repurposed to target autoreactive B-cells, which produce the pathogenic antibodies responsible for many autoimmune diseases. These therapies use engineered T-cells to target CD19, a surface marker expressed on B-cells, leading to the selective depletion of both active and precursor B-cells in the patient’s body. This process induces a state of temporary B-cell aplasia, effectively eliminating the production of autoimmune antibodies. While all antibody production will be eliminated during the period of B-cell aplasia, benign antibodies can be replaced with IgG supplementation, and other arms of the immune system remain intact. Unlike traditional immunosuppressive therapies, which broadly dampen immune responses and dramatically increase infection risks, CAR-T cells provide a targeted and efficient solution, minimizing collateral damage to the immune system. One of the most transformative aspects of CAR-T cell therapy in autoimmune diseases is its potential to act as an “immune reset button.” After several months of induced B-cell aplasia, the patient’s own B-cells regenerate, but without the autoreactive characteristics that fueled the autoimmune response. This not only resolves the immediate symptoms but also fosters long-term remission of disease. Early clinical trials have reported remarkable outcomes, with significant improvements in disease-specific symptoms, tissue repair, and overall immune system normalization. Notably, these benefits have been achieved with a favorable safety profile, as patients experienced no severe toxicity or relapse during follow-up periods. As research advances, CAR-T therapies could revolutionize treatment paradigms for refractory autoimmune diseases, offering a precision medicine approach with durable and potentially curative outcomes for conditions that were once considered untreatable. CAR-T Therapy in Solid Tumors While CAR-T cell therapy has shown remarkable success in hematologic malignancies, or "liquid tumors," translating this success to solid tumors has been more challenging due to the distinct characteristics of these cancers. One of the primary obstacles is the immunosuppressive tumor microenvironment (TME), which actively inhibits T-cell function. Additionally, solid tumors often exhibit antigen heterogeneity, meaning that tumor cells may express different or varying levels of target antigens, leading to potential evasion of CAR-T cell detection. Moreover, the antigens expressed by solid tumors are often not unique to malignant cells, leading to CAR-T cell recognition and destruction of benign cells and off-target toxicity. Finally, physical barriers such as dense extracellular matrix and irregular tumor vasculature further limit the infiltration and effectiveness of CAR-T cells. These factors necessitate innovative engineering strategies to enhance the potency and applicability of CAR-T therapies in solid tumors. Several advancements aim to overcome these challenges and improve CAR-T therapy outcomes in solid tumors. Engineering CAR-T cells to secrete cytokines or chemokines helps recruit additional immune cells to the tumor site and counteract the immunosuppressive effects of the TME. Dual-targeting CARs, which recognize multiple antigens, address the issue of tumor heterogeneity by reducing the likelihood of antigen escape and helping contain CAR-T cell activity to only malignant cells. In a similar vein, including expression of novel co-stimulatory domains in CAR-T cells can enhance their activity, especially in the hostile tumor microenvironment. Furthermore, modifications to express enzymes like heparanase facilitate the degradation of the extracellular matrix, improving CAR-T cell penetration into dense tumor tissue. Safety enhancements, including switchable CAR designs and transient gene modifications, provide greater control over T-cell activity, reducing the risk of off-target effects and toxicity. Collectively, these innovations aim to enhance the persistence, efficacy, and safety of CAR-T cells, offering new hope for treating the complex and diverse landscape of solid tumors. Further Reading: 1.      Schett, G., Mackensen, A., & Mougiakakos, D. (2023). CAR T-cell therapy in autoimmune diseases.  The Lancet ,  402 (10416), 2034-2044. 2.      Schett, G., Müller, F., Taubmann, J., Mackensen, A., Wang, W., Furie, R. A., ... & Mougiakakos, D. (2024). Advancements and challenges in CAR T cell therapy in autoimmune diseases.  Nature Reviews Rheumatology ,  20 (9), 531-544. 3.      Albelda, S. M. (2024). CAR T cell therapy for patients with solid tumours: key lessons to learn and unlearn.  Nature Reviews Clinical Oncology ,  21 (1), 47-66. 4.      Newick, K., O'Brien, S., Moon, E., & Albelda, S. M. (2017). CAR T cell therapy for solid tumors.  Annual review of medicine ,  68 (1), 139-152.

Case Introduction A 27-year-old man presents with chronic granulomatous disease (CGD). CGD is a collection of inherited immune deficiencies in which phagocytes, particularly neutrophils, are unable to generate reactive oxygen species and kill certain types of bacteria and fungi due to mutations in the NADPH oxidase enzyme complex. The definitive treatment for CGD is a stem cell transplant from a healthy donor to replace the phagocyte lineage with functioning cells. In this case, our patient presents for gene therapy in which his own stem cells are collected, genetically modified to be able to produce normal NADPH oxidase, and then reinfused. We first meet our patient about a month after his gene therapy while he is still battling multiple chronic fungal infections related to his underlying CGD. We see he underwent myeloablative conditioning, which means he received high doses of chemotherapy to complete remove all his blood cells before he received the new, genetically modified stem cells. It’s important to note that myeloablative conditioning causes more toxicity to the patient, which we will come back to later. Looking in his chart, we see that that the new stem cells seemed to have found a home in his bone marrow because his red blood cells and platelets initially recovered. However, over the past week, he has experienced worsening anemia and thrombocytopenia. We also see elevated hemolysis markers, up-trending BUN and creatinine, and normal coagulation tests. Finally, the team performed a peripheral smear and found schistocytes. What is this all suspicious for? Why thrombotic microangiopathy (TMA)! What is TMA? TMA is fundamentally a disorder of endothelium and primarily affects small blood vessels and capillaries. In TMA, damaged endothelium acts as a nexus for the accumulation of platelet-rich microthrombi which function as a physical barrier and cause mechanical destruction of red blood cells, resulting in the hallmark schistocytes seen in this disorder. This mechanical hemolytic anemia results in the classic laboratory values of TMA – low hemoglobin and undetectable haptoglobin, with elevated bilirubin and LDH. The build up of the toxic byproducts combined with reduced flow through capillary beds leads to end organ damage, particularly of the kidneys which are especially vulnerable to excess free hemoglobin. For this reason, TMA is often associated with kidney injury or failure. Pathophysiology of TMA There are number of pathways through which TMA can occur, which can be generally grouped into ADAMTS13 deficiency, inappropriate complement activation, Shiga toxin, and inappropriate coagulation activation. ADAMTS13 Deficiency : ADAMTS13 is an enzyme that cleaves von Willebrand factor (vWF) multimers into a ‘goldilocks’ size: neither too big nor too small. Absence or deficiency of ADAMTS13, either through an inherited defect or the acquisition of an autoantibody, leads to the accumulation of large vWF multimers, which then bind to platelets and result in the development of platelet rich microthrombi. Also known as thrombotic thrombocytopenic purpura (TTP), ADAMTS13 deficiency has a mortality rate of ~90% without treatment; thus, when it is suspected treatment must be initiated immediately. Suspicion of TTP is a hematologic emergency. Inappropriate Complement Activation : systemic endothelial injury leads to systemic complement activation and increased soluble C5b-9 levels. Pathologically activated complement then interacts with damaged endothelium, eventually leading to platelet activation and the accumulation of platelet rich microthrombi. Shiga Toxin : Shiga or Shiga-like toxin released by microorganisms enters cells and irreversibly inhibits protein synthesis by damaging the ribosome, ultimately resulting in cell death. Endothelium anywhere in the body can be damaged by these toxins, resulting in complement activation and the generation of platelet rich microthrombi in a similar fashion to the above; however, the endothelium of the kidney is particularly prone to damage following exposure to Shiga or Shiga-like toxin, resulting in the hallmark renal failure of hemolytic uremic syndrome (HUS). Inappropriate Coagulation Activation : While inappropriate complement activation is a well-characterized underlying cause of TMA, inappropriate coagulation activation can also result in platelet-rich microthrombi in small vessels. Coagulation-mediated TMA is much rarer, usually resulting from genetic mutations in coagulation regulators, and typically presents in young children. Causes of TMA Most TMA is secondary to systemic endothelial injury, which can be from a variety of sources. Examples include HELLP syndrome in pregnancy, malignant hypertension, infections, malignancy, some classes of drugs, and stem cell transplant. Primary causes of TMA are less frequent, but when present typically arise from either acquired autoantibodies to ADAMTS13, resulting in ADAMTS13 deficiency, or acquired autoantibodies to complement regulators, resulting in inappropriate complement activation. In rare cases, ADAMTS13 or complement regulator deficiency can arise from inherited genetic disorders. Differential Diagnosis of This Case In the case we present above, a 27-year-old man underwent a transplant with his own stem cells after genetic modification. To prepare for this transplant, he received an intensive chemotherapy regimen, and in the wake of his transplant he develops signs and symptoms of TMA. We discussed that stem cell transplants are associated with TMA, and this entity is formally known as Transplant Associated TMA, or TA-TMA, which we discuss in further detail below. However, because ADAMTS13 deficiency/TTP cannot be immediately ruled out, and because the mortality rate is so high, this must also be considered in the differential. What is TA-TMA?   Unfortunately, diagnostic criteria for TA-TMA vary, and moreover this entity exists in a spectrum of other transplant associated syndromes involving damage to the endothelium, making TA-TMA difficult to recognize and diagnose. While current estimates are that TA-TMA occurs in ~8% of all stem cell transplants, this is likely an under-estimate and the true prevalence of TA-TMA is unknown. Pathophysiology of TA-TMA Current literature suggests that TA-TMA is likely a multifactorial process involving multiple hits. First, there is likely an underlying predisposition through either pre-existing systemic complement activation or systemic endothelial injury. Second, this underlying predisposition is exacerbated by a toxic conditioning regimen, such as the intensive, myeloablative chemotherapy that our patient underwent. Finally, the third hit is infection. Infections are common in the peri-transplant period while patients have additional immunosuppression, and in the case of our patient, he had multiple chronic infections from his underlying CGD. Studies are also elucidating additional factors that may impact the development of TA-TMA following a stem cell transplant. For example, there is some evidence that acquisition of complement regulator variants from a donor may increase risk of TA-TMA, although this does not apply to our patient as his transplant was autologous. Research has also found a higher rate of TA-TMA in cases with co-morbid graft versus host disease, indicating that the course of the transplant itself may influence the health of endothelial cells and the development of TA-TMA. Finally, there are factors specific to the recipient that influence TA-TMA. Studies have found that recipients with the HLA-DRB1*11 allele have better outcomes if they do develop TA-TMA. Treatment for TA-TMA Eculizumab There is a diversity of treatments for TA-TMA that target different aspects of the pathophysiology, and in some cases overlap with treatment for the spectrum of endothelial disorders that can arise in the peri-transplant setting. Despite all this diversity, most experts agree that eculizumab, a monoclonal antibody that neutralizes C5 and thus inhibits complement activation, is a mainstay of treatment for TA-TMA. In most institutions, the regimen for TA-TMA will include eculizumab, although this may be in the setting of other drugs or treatment modalities. TPE in TA-TMA Therapeutic plasma exchange (TPE) is not a mainstay of treatment for TA-TMA. In fact, some studies report worse outcomes in patients with TA-TMA who have undergone a course of TPE, although there may be a role for TPE if TA-TMA occurs in the setting of autoantibodies to complement regulators. These cases are rare, and currently guidelines recommend that TPE be deferred until such autoantibodies can be definitively identified by laboratory methods. Treatment for TTP First Line Unlike TA-TMA, TPE is a first-line therapy for TTP. Through TPE, autoantibodies to ADAMTS13 and large vWF multimers are removed, while the infusion of donor plasma restores some functional ADAMTS13. Generally, a course of daily 1.0 volume TPE with plasma as a replacement fluid is started on an emergent basis when TTP is suspected, given the extremely high mortality rate of untreated TTP. Steroids also have a role to dampen the immune response and inhibit further production of autoantibodies. Emerging While TPE and steroids remain first-line, there have been advancements in therapy for TTP. Recent evidence suggests a role for early rituximab, a monoclonal antibody to CD20 that results in the removal of antibody-producing B-cells. While rituximab was previously used in refractory cases of TTP, studies have found earlier remission and significant reductions in relapses over a 10-year follow-up when rituximab is utilized early in the disease course – within 3 days of symptoms onset. There is also a newer antibody-based treatment for TTP: caplacizumab. This drug is not a traditional monoclonal antibody but is a modified version of a camelid antibody. Found only in the Camelid family of mammals, camelid antibodies are a unique type of immunoglobulin that are smaller and more maneuverable than traditional monoclonal antibodies. Because these molecules can fit into tight spaces, they act as excellent neutralizing agents. Caplacizumab is specific for the A1 domain of vWF, through which vWF binds platelets. By neutralizing the A1 domain, the accumulation of platelets on large multimers of vWF and the development of platelet-rich microthrombi is prevented. Caplacizumab was shown to reduce time to remission but remains prohibitively expensive for most institutions to carry in their formulary.  Wrap Up of the Case In our case, the patient develops signs and symptoms of TMA following an autologous transplant with genetically modified stem cells. The leading diagnosis is TA-TMA, but TTP cannot be initially ruled out. To work up TTP, a sample to test for ADAMTS13 activity is drawn. It is critical to draw this sample BEFORE any donor plasma enters the patient, as donor plasma will falsely increase the ADAMTS13 activity level. Because TTP is a rare entity, most hospitals don’t have ADAMTS13 activity levels performed in house but rather send them out; thus, it can take several days for the results to return and provide insight on the likelihood of TTP. While awaiting the ADAMTS13 activity level results it is standard to perform a short course of TPE. In the case of our patient, coordination of the staff and materials to perform TPE took about 12 hours, and this is not uncommon across institutions. However, an initial delay in TPE does not prohibit any treatment at all. In such instances, a simple plasma transfusion can help restore ADAMTS13 activity and prevent mortality while awaiting definitive therapy. In the case of our patient, he did receive an infusion of 2 units of FFP prior to his first full TPE. Additional work-up to assess the likelihood of TA-TMA was also performed. First, levels of complement proteins were assayed. In general, levels of complement protein are significantly elevated in TA-TMA and other forms of complement mediated TMA. Soluble levels of C5b-9, and plasma levels of C3b and Ba, can all provide insight on the activity of the complement system. However, these assays simply measure levels and do not determine function. While rarely performed, the CH50 assay will provide functional information on the complement system. In the CH50 assay, patient serum is added to sheep red blood cells that are coated in antibody. The amount of RBC lysis is then measured, with higher levels of lysis indicating excessive complement activity. In the case of our patient, complement levels were elevated, and a CH50 assay was not performed. After 2 sessions of daily TPE, our patient’s ADAMTS13 result returned as normal (ADAMTS13 activity > 70%). Because further TPE could produce worse outcomes in the likely diagnosis of TA-TMA, no further TPE was performed. Instead, the patient was started on regimen of eculizumab and slowly began to improve. After an additional week in the ICU, he was discharged to the floor.

50yoM with controlled HIV presented with slowly enlarging inguinal lymphadenopathy over the last 9 months. Flow cytometry and lymph node biopsy revealed an aberrant population of lymphoid cells. Here's the H&E: Here are the results of IHC: Stain Result CD3 Negative CD4 Positive CD5 Positive CD20 Negative CD30 Positive CD45 Positive ALK1 Positive What is the diagnosis? Anaplastic Large Cell Lymphoma (ALCL) – ALK-positive! A subtype of peripheral T-cell lymphoma, it classically presents as large cells with abundant cytoplasm, pleomorphic, horseshoe-shaped nuclei, and CD30 positivity.   The presence of Alk1 positivity is associated with translocation t(2;5) producing the ALK1 :: NMP1  fusion gene. It is frequently associated with HIV, mycosis fungiodes, and pulmonary pseudotumors. The main differentials include Hodgkins Lymphoma (also CD30+, CD3-, CD20-), and Alk-negative ALCL.   Known as a moderately aggressive tumor, it has an overall prognosis better than other peripheral T cell lymphomas, including Alk1 negative ALCL, with 5 year survival of 80%. The presence of MYC rearrangement, small cell morphology, or lymphohistiocytic variant indicate a poor prognosis.   References: https://www.ncbi.nlm.nih.gov/books/NBK537150/ .

Here's something I never thought I'd say: I spent the afternoon coding with ChatGPT 4.0. In about 3 hours I was able to turn out an updated, polished, robust, and future-proofed piece of code to assist blood bankers with selecting HLA compatible platelets. When used judiciously and wisely, large language models like ChatGPT truly are incredible tools. After finishing the code, I composed this post with ChatGPT. You'll notice it's not really my voice, but it captures all the essential points I wanted to make. Full disclosure: the following text was produced with ChatGPT. Automation is transforming medicine by streamlining complex workflows, minimizing human error, and enabling healthcare professionals to focus on patient care. In transfusion medicine, automation has the potential to revolutionize tasks like platelet compatibility matching, where precision and efficiency are vital. Through the power of coding, we recently embarked on a project to automate HLA platelet matching, creating a tool that simplifies this intricate process and produces clear, professional results. Platelet compatibility largely hinges on matching donor and recipient Human Leukocyte Antigens (HLA), a mismatch of which is the most common underlying factor in platelet refractoriness. The process involves utilizing a number of different methods, but most commonly revolves around bioinformatic data from services like HLA MatchMaker, and Mean Fluorescence Intensity (MFI) values which are a semi-quantitative assessment of HLA antibody strength. Avoidance notes to prevent alloimmunization against future donor antigens is also important. MFI values can be summed to produce a compatibility score, and while this process is time-consuming and error prone, it does allow selection of the most suitable platelet units while avoiding those that may trigger rejection. Manually calculating HLA compatibility from MFI involves sorting through large datasets of donor and recipient information, correctly matching HLA antigens, and ensuring the correct application of MFI scores, all of which requires significant attention to detail. The risk of human error looms large, and the process can be daunting for even experienced professionals. Automation, on the other hand, eliminates these drawbacks, offering consistent accuracy, faster turnaround times, and the ability to scale workflows seamlessly. The code we developed today showcases the benefits of automation. By parsing recipient and donor files, expanding HLA antigens into standardized formats, and calculating compatibility scores programmatically, the tool significantly reduces the potential for manual errors. The system also handles duplicate avoidance notes efficiently and generates a polished Word document report with tables formatted for clarity. Designed with future-proofing in mind, the code is modular and adaptable for future updates, ensuring it can grow alongside evolving needs in transfusion medicine. The output generated by the tool is a comprehensive Word document that is both readable and usable. Platelet units are ranked in order of decreasing compatibility, tables are presented in landscape orientation for better visibility, and column widths are tailored, particularly for the Avoids column, to display longer text. The use of bold headers and subtle shading enhances readability, making it easier for blood bankers to review compatibility results at a glance. By combining automation with user-centric design, the final output serves as a powerful decision-making tool. Looking ahead, the project can be improved by embedding detailed instructions for use directly into the code. This ensures the tool remains accessible and easy to use, even if external instruction files are misplaced. Additionally, building a robust test harness will facilitate future updates and maintain code reliability as the tool evolves. With these enhancements, the system can become an even more indispensable asset for transfusion medicine teams. Automation and coding are powerful allies in modern medicine, bridging the gap between complex data analysis and actionable insights. By reducing human error and enhancing workflows, these tools empower healthcare professionals to provide safer and more efficient patient care. For those looking to harness this potential, learning to use tools like ChatGPT for coding can be a transformative first step. With creativity and determination, coding can open doors to endless possibilities in healthcare innovation.

In 2021 I co-founded the Society for Innovation and Research (SIR) while in my clinical pathology residency. Our goal was to promote and support resident participation in research and innovation. Using PubMed indexed publications as a metric of success, we found that SIR more than doubled the average number of resident publications, while also increasing the average number of residents publishing and the average number of co-authored publications (a surrogate for collaboration within the residency program). In short, SIR was a breakout success. Efforts to promote resident research productivity often emphasize grant funding in their curricula; however, with SIR we avoided the subject entirely for two reasons. First, obtaining grant-funding is largely inaccessible while in clinical training, and second the rigors of sustaining grant-funded research are unattractive to many residents, who as a cohort are starting to emphasize lifestyle in their career choices. Instead of emphasizing applying for grants and spending precious free hours at the bench, we introduced a new paradigm of research and participation in science in graduate medical education, with “one foot only in the ivory tower”. In doing so, we considered the following three major points. First, doctors need to be educated consumers of scientific literature. SIR featured monthly workshops during which residents presented works in progress to their co-residents, who then participated in giving critical feedback. Thus, residents in the audience built critical thinking skills about collecting, analyzing, and displaying data in an experiential fashion. It was our belief that this experiential learning would solidify the importance of critical thinking better than simply reading and discussing literature. Second, most residents will not have the time to participate in discovery research. Yet, this does not mean they cannot participate in research at all. In SIR we emphasized retrospective chart reviews and case reports, both being more attainable for busy residents. We routinely utilized TriNetX, a deidentified clinical database from institutions across the world, and in doing so introduced skills in bioinformatics and data science, which are becoming more critical with every passing year. These kinds of projects can still produce valuable results, and largely do not require grant funding. By shifting focus away from the long tradition of grant-funded bench work, we gave residents the tools to participate in research for years to come, whether they opt to pursue grant funding or not. Third, communicating science is of the upmost importance with the uptick of health misinformation spreading across social media, and should be a major goal of any research oriented program in graduate medical education. SIR workshops allowed residents to not only practice presenting projects, but also to hear their co-residents present and observe what worked well. In summary, we shouldn’t teach research skills to residents with the framework that everyone needs to be a grant-funded researcher to be successful, or that this is the pinnacle of participation in the scientific endeavor. Current residents are becoming doctors in an era in which scientific literacy is in decline, and much of the joy of science has been lost to hyper-competitive grant funding and relentless productivity metrics. We should be introducing new paradigms of accessible research to residents, as we did in SIR, as it is more critical than ever that they embrace the scientific endeavor to improve the conditions of humanity.

In this post we’re going to talk about sequencing and genomics, and I hope it’s as educational for you as it was for me.   Let’s start by putting sequencing in perspective. There are a variety of methods we use in molecular pathology, each of which tells us different information about the genome of our patient. I find to helpful to think of molecular methods as dividable into two bins: methods that give us structural information and methods that give us sequence information. Remember that the genome is not just a string of base pairs; all that DNA is eloquently wrapped around histones and packed into chromatin, which is further organized into supercoiled DNA, which ultimately becomes a chromosome. The genome itself occurs on a scale from base pair to chromosome, and similarly we need methods that can give us information across this scale.   In the structural bin, we have karyotypes and fluorescence in situ hybridization (FISH). Karyotypes involve the collection of condensed chromosomes at metaphase, staining thereof (several different methods for this), and then arrangement into chromosome pairs for analysis of differences. FISH involves the hybridization of fluorescently labeled probes, but in order to get good detection of that probe it has to be fairly large, between 1 mega base pair and 100 kilo base pairs. Both karyotype and FISH are good for structural information like translocations, as well as medium-large insertions and deletions.   In the sequence bin we have sequencing, which we will talk about more in a minute, and chromosomal microarray (CMA). Like FISH, CMA involves the hybridization of probes, but their scale is much smaller – only 5-10 kilo base pairs. Because of this, CMA can give limited information on sequence. However, it is really best for copy number changes, such as unbalanced translocations, and smaller deletions and insertions. It’s important to remember that CMA cannot detect a balanced translocation, and for this you will need to use either karyotype or FISH. Karyotype FISH CMA Sequencing Useful for Chromosome Chromatin Chromatin/ Base pair Base pair Resolution (in base pairs, bp) 5 mega bp 1 mega - 100 kilo bp 5-10 kilo bp 1 bp Good for Translocations, Large deletions and insertions Translocations, Medium deletions and insertions Unbalanced translocations, Smaller deletions and insertions, Limited base pair data Smallest deletions and insertions, Single base pair changes Bad for Sequence data Sequence data Balanced translocations, Structural information Structural information   Table credit: Caitlin Raymond Then there is sequencing, which can only give information about the base pairs in string of DNA, and cannot give information about structure. It can detect the smallest deletions and insertions, as well as single base pair changes. Sequencing began with the Sanger method, which is labor intensive and limited to about 1 kilo base pair of output. However, new sequencing platforms have come on the market, and we’ll talk about two of particular interest here: next generation sequencing (NGS) and nanopore sequencing.   There are multiple platforms for NGS, which vary in their technical details. What they have in common is that each platform uses massively parallel sequencing of many small DNA fragments attached to a solid surface. Sequencing may occur by adding only one nucleotide at a time and assessing for its incorporation (pyrosequencing, ion semiconductor sequencing), or by adding a mixture of reversibly terminal nucleotides conjugated to a unique florescent probe (sequencing by synthesis). Regardless of the technical details, NGS systems output a massive amount of sequencing data, much more so than the Sanger sequencing method that preceded them. All that data can be collated to sequence large segments of DNA rapidly and efficiently, including whole genomes.  Image source: https://www.researchgate.net/figure/Comparison-between-Sanger-sequencing-and-next-generation-sequencing-NGS-technologies_fig2_260197220 Nanopore sequencing, in contrast to most forms of NGS, does not utilize a DNA polymerase. Instead, a helicase sits atop a nanopore that crosses a membrane barrier. The helicase extrudes a single strand of the DNA through the nanopore, which has an ionic current running through it. Each nucleotide makes a predictable change in the current as it passes through the narrowest aperture of the nanopore, and the sequence is determined. Nanopore sequencing can produce reads for hundreds of kilo bases, and across stretches of DNA that are not easily sequenceable through other methods, such as telomeres and centromeres.  Image source: https://www.genome.gov/genetics-glossary/Nanopore-DNA-Sequencing In order to understand the role of these newer sequencing technologies in genomics, it helps to know a little of the history of the human genome. The original Human Genome Project launched in 1990, and in 2003 they announced that they had sequenced 92% of 10 samples. That remaining 8% included difficult to sequence regions like telomeres, and just recently in 2022 the Telomere to Telomere project released the first ever fully sequenced human genome. You’ll also note that only 10 samples were sequenced in the Human Genome Project, hardly a representative sample. In 2008, the 1,000 Genomes Project was launched, aiming to fully sequence 1,000 samples of the human genome from around the globe.   Image credit: Caitlin Raymond To make sense of all this data, the Encyclopedia of DNA Elements (ENCODE) Project was launched, aiming to produce a comprehensive database of all functional elements in the human genome. The National Institutes of Health also stated two centers to investigate the role of genetics in human disease. The Common Disease Genomics center aims to understand the role of genetics in common diseases such as diabetes and high blood pressure. In contrast, the Centers for Mendelian Genomics aims to further study the role of specific genes in the development of inherited diseases, such as cystic fibrosis.   In terms of classifying the results of this data, two terms are commonly used, but frequently misunderstood. A polymorphism, or single nucleotide polymorphism (SNP), is a sequence change at a single base pair that is present in ≥ 1% of the reference genome. A variant is a sequence change present at < 1% of the reference genome. Obviously, as more genomes and sequences are added to the reference database, we’ll have a better understanding of which sequence changes are SNPs and which are variants.   Variants are often investigated for links to disease states, and are currently classified on a five-point scale: benign, likely benign, unknown significance, likely pathogenic, and pathogenic. Variants and their assigned classification can be found in the ClinVar database, which is freely available online. With so much yet unknown about the human genome and how it influences disease, it can come as little surprise that assigning a category to a variant is challenging, and sometimes variants are reclassified based on updated studies in the scientific literature. Most often, a variant with unknown significance (VUS) is reassigned to either the benign or pathogenic categories. In a recent study, Veenstra et al. found that most VUS are being reclassified as benign as we learn more about the diversity of the human genome [1]; however, some still are being reclassified as pathogenic. SoRelle et al. published similar findings, and moreover found that the rate at which VUS are being reclassified is steadily increasing [2]. In 2018, Mersch et al. found that the average time to reclassification of a VUS dropped from a mean of ~2.5 years to less than 1 year between 2006 and 2016, with no sign of slowing down [3].   This raises an important question: if a patient was notified of a VUS in their clinical sequencing results, and the status of that VUS changes, do we have a duty to inform the patient? A minority of clinical genetics centers are already doing so. In a 2018 survey of 105 genetics centers, 26 (or ~25%) responded that they were routinely recontacting patients if a VUS in their results was reclassified [4]. However, the issue of consent for recontacting has not been fully addressed. When do patients consent to recontact for updated information about their clinical genetics results? What if they do not consent? In a survey about their preferences regarding recontact, 50.4% of patients declined to receive updates about their results, commonly citing concerns about insurability [5]. Another as yet unanswered question is who will be responsible for updating the patient? In a 2019 statement, the American College of Medical Genetics suggested the ordering provider bear chief responsibility, but that patients, consulting geneticists, clinical labs, and even research laboratories all shared some responsibility in making this possible.   Image credit: Caitlin Raymond To summarize, big data has arrived in genomics with new sequencing technologies enabling the production of huge datasets. With all this data our understanding of polymorphisms and particularly variants is rapidly changing, and there is ongoing debate about how to convey this to patients.   I’d like to close with some thought for the societal impact of big data in genomics. Technology in molecular pathology is racing ahead, with societal customs and our legal system struggling to keep up. The next 10 years will be critical to lay a fair groundwork for who gets access to this data and how this data is used. "One of my concerns has been the limits on applications of our understanding of the genome. Should there be limits? I think there should. I think the public has expressed heir concenr about ways this information might be misused." - Francis Collins   1.       Veenstra, D. L., Rowe, J., Pagán, J. A., Brown, H. S., Schneider, J., Gupta, A., ... & Appelbaum, P. S. (2021). Reimbursement for genetic variant reinterpretation: 5 questions payers should ask.  The American journal of managed care ,  27 (10), e336. 2.       SoRelle JA, Thodeson DM, Arnold S, Gotway G, Park JY. Clinical Utility of Reinterpreting Previously Reported Genomic Epilepsy Test Results for Pediatric Patients.  JAMA Pediatr.  2019;173(1):e182302. doi:10.1001/jamapediatrics.2018.2302 3.       Mersch J, Brown N, Pirzadeh-Miller S, Mundt E, Cox HC, Brown K, Aston M, Esterling L, Manley S, Ross T. Prevalence of Variant Reclassification Following Hereditary Cancer Genetic Testing. JAMA. 2018 Sep 25;320(12):1266-1274. doi: 10.1001/jama.2018.13152. PMID: 30264118; PMCID: PMC6233618. 4.       Sirchia F, Carrieri D, Dheensa S, et al. Recontacting or not recontacting? A survey of current practices in clinical genetics centres in Europe. Eur J Hum Genet. 2018 Jul;26(7):946-954. doi: 10.1038/s41431-018-0131-5. Epub 2018 Apr 23. PMID: 29681620; PMCID: PMC6018700. 5.       Henrikson NB, Scrol A, Leppig KA, Ralston JD, Larson EB, Jarvik GP. Preferences of biobank participants for receiving actionable genomic test results: results of a recontacting study. Genet Med. 2021 Jun;23(6):1163-1166. doi: 10.1038/s41436-021-01111-2. Epub 2021 Feb 18. PMID: 33603197; PMCID: PMC8194390. 6.       David, K.L., Best, R.G., Brenman, L.M.  et al.  Patient re-contact after revision of genomic test results: points to consider—a statement of the American College of Medical Genetics and Genomics (ACMG).  Genet Med  21, 769–771 (2019). https://doi.org/10.1038/s41436-018-0391-z