Circulating cell-free DNA (cfDNA) fragments are a biological analyte with extensive utility in diagnostic medicine. Understanding the source of cfDNA and mechanisms of release is crucial for designing and interpreting cfDNA-based liquid biopsy assays. Using cell type-specific methylation markers as well as genome-wide methylation analysis, we determine that megakaryocytes, the precursors of anuclear platelets, are major contributors to cfDNA (~26%), while erythroblasts contribute 1–4% of cfDNA in healthy individuals. Surprisingly, we discover that platelets contain genomic DNA fragments originating in megakaryocytes, contrary to the general understanding that platelets lack genomic DNA. Megakaryocyte-derived cfDNA is increased in pathologies involving increased platelet production (Essential Thrombocythemia, Idiopathic Thrombocytopenic Purpura) and decreased upon reduced platelet production due to chemotherapy-induced bone marrow suppression. Similarly, erythroblast cfDNA is reflective of erythrocyte production and is elevated in patients with thalassemia. Megakaryocyte- and erythroblast-specific DNA methylation patterns can thus serve as biomarkers for pathologies involving increased or decreased thrombopoiesis and erythropoiesis, which can aid in determining the etiology of aberrant levels of erythrocytes and platelets.

Circulating cell-free DNA (cfDNA) fragments are a biological analyte with extensive utility in diagnostic medicine. Understanding the source of cfDNA and mechanisms of release is crucial for designing and interpreting cfDNA-based liquid biopsy assays. Using cell type-specific methylation markers as well as genome-wide methylation analysis, we determined that megakaryocytes, the precursors of anuclear platelets, are major contributors to cfDNA (∼26%), while erythroblasts contribute 1-4% of cfDNA in healthy individuals. Surprisingly, we discovered that platelets contain genomic DNA fragments originating in megakaryocytes, contrary to the general understanding that platelets lack genomic DNA. Megakaryocyte-derived cfDNA is increased in pathologies involving increased platelet production (Essential Thrombocythemia, Idiopathic Thrombocytopenic Purpura) and decreased upon reduced platelet production due to chemotherapy-induced bone marrow suppression. Similarly, erythroblast cfDNA is reflective of erythrocyte production and is elevated in patients with Thalassemia. Megakaryocyte- and erythroblast-specific DNA methylation patterns can thus serve as novel biomarkers for pathologies involving increased or decreased thrombopoiesis and erythropoiesis, which can aid in determining the etiology of aberrant levels of erythrocytes and platelets. GRAPHICAL ABSTRACT

Non-bacterial thrombotic endocarditis is an uncommon entity that tends to be related to malignancy or rheumatological disorders. The diagnosis is complex and requires a high index of suspicion. It commonly causes recurrent emboli; however, coronary embolism remains an infrequently reported entity. Herein we report a unique case of sequential pulmonary embolism, ST-elevation myocardial infarction (MI), and stroke associated with multi-valvular non-bacterial thrombotic endocarditis. The cornerstone of management is treating the underlying cause and anticoagulation therapy. Surgical treatment should be considered in patients with acute heart failure secondary to valvular dysfunction and recurrent thromboembolism despite proper anticoagulation. We have performed an extensive literature search and found nine cases of established antemortem diagnosis of myocardial infarction secondary to non-bacterial thrombotic endocarditis, and we reviewed them according to cause, treatment, and outcome.

Background: B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor T-cell (CAR-T) therapy has demonstrated substantial efficacy in relapsed and/or refractory multiple myeloma. While toxicities such as cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) have been well characterized, the incidence and clinical consequences of the coagulopathy associated with CRS remain underexplored. Methods: We conducted a prospective analysis of 108 adult patients with multiple myeloma or light chain amyloidosis treated with the academic anti-BCMA CAR-T HBI0101 in a single-center trial (NCT04720313). Coagulopathy was evaluated via serial fibrinogen measurements, with hypofibrinogenemia defined as <200 mg/dL and severe coagulopathy as <100 mg/dL. Laboratory markers, tocilizumab and blood product use, and thrombotic and bleeding complications were recorded. Patients received a short (3-day) or extended course of enoxaparin thromboprophylaxis as well as fresh frozen plasma in cases of severe coagulopathy. Results: CRS grades 1–3 occurred in 100 patients (93%). Hypofibrinogenemia was observed in 79 patients (73%), including 20 (19%) with severe coagulopathy. Fibrinogen levels were significantly associated with CRS severity (p < 0.001), number of tocilizumab doses (p < 0.001), peak levels of the inflammation markers LDH (p = 0.001) and ferritin (p = 0.006), and neutropenia (p = 0.33). Five thrombotic events (4.6%) and three minor bleeding events (2.7%) occurred within 3 months post-CAR-T infusion and were not associated with degree of coagulopathy or CRS. No cases of major bleeding or fatal thrombosis occurred. Conclusions: CRS-related coagulopathy is common following BCMA-targeted CAR-T treatment and correlates closely with CRS severity. Despite the high rate of laboratory coagulopathy, thrombosis and bleeding events were infrequent, suggesting the benefit of the prophylactic strategies used.