New Mechanistic Insights & Therapeutic Applications of Megakaryocytes/Platelets

摘要 这是马里兰州莫蒂默·庞茨申请NHLBI支持的R35杰出研究员奖 (Oia)。庞茨博士在血小板(Plt)生物学领域做出了开创性的贡献。他与世隔绝，充满魅力- 命名为Plt蛋白(整合素链，AIIb和b3，以及趋化因子， 血小板因子4(PF4)和b-血栓球蛋白)。他描述了遗传性Plt的第一个分子缺陷 疾病，Glanzmann血栓减少症(GT)。30多年来，Poncz博士在以下方面做出了深刻贡献 将Plt字段向前移动。他帮助我们加深了对巨核细胞生成的理解，定义了许多 转录因子(TF)在这一过程中的基础及其在遗传性Plt疾病中的作用。他 率先使用诱导多能干细胞(IPSCs)研究巨核细胞(MEG)生物学和 展示了第一个从基因上纠正GT和巴黎-特鲁索综合征缺陷的策略。 庞茨博士建议对观察到的血小板减少症的分子基础寻求新的见解 RUNX1单倍体不足，以及这种干预如何降低白血病转化的风险 受影响的病人。这种对巨核细胞生成的兴趣也导致了庞茨博士对理解 Plts被释放的地方，显示注入的Megs在肺部释放Plt。由此产生的Plts是 比迄今为止从体外培养的Megs释放的任何体外生成的Plts都更具生理学意义。这些研究 其他人的后续研究支持部分血栓形成的潜在肺部位 为这一模型提供现场支持。Poncz博士现在表明，肺微毛细血管床在 能够释放Plts。拟议的研究将进一步加深我们对肺床形成原因的理解 在血栓形成方面是独一无二的，这种见解可能在Plt输血中有临床应用。Poncz博士还 提出Plts可以将异位蛋白储存在颗粒中，以一种有针对性的、有效的方式在 血管损伤的部位。他建议通过一种新的新的方法来促进Plt靶向疗法的使用 凝血因子VIII拮抗剂治疗血友病A患者的机制研究 该药可用于预防血栓形成，并可与尿激酶型一起用作血栓预防药物。Poncz博士还将我们的 了解血栓前肝素诱导的血小板减少症(HIT)的分子基础。他的 HIT-like抗体KKO和HIT的小鼠模型在该领域得到了广泛的应用，这两种模型都在他最近的 中性粒细胞胞外陷阱(Net)在HIT中作用的研究进展他现在提出， 像Net这样的聚阴离子是HIT促血栓形成的基础，并将在这款R35中测试这一点。此外，他还 相信这些新的见解对其他血栓性炎症性疾病的治疗具有启示意义 NET在脓毒症的治疗中起着重要的作用，建议使用PF4和FC修饰的KKO治疗败血症 和镰状细胞病。来自R35 OIA机制的支持也将为Poncz博士提供时间来 追求他的另一种激情--在良性血液学相关领域推进受训者的职业生涯。

ABSTRACT This is an application by Mortimer Poncz, MD, for an NHLBI-supported R35 Outstanding Investigator Award (OIA). Dr. Poncz has made pioneering contributions to the field of platelet (Plt) biology. He isolated and charac- terized the first cDNAs and genes for the Plt proteins (integrin chains, aIIb and b3, and the chemokines, platelet factor 4 (PF4) and b-thromboglobulin). He characterized the first molecular defects in an inherited Plt disorder, Glanzmann thrombasthenia (GT). For over 30 years, Dr. Poncz has made insightful contributions to move the Plt field forward. He helped advance our understanding of megakaryopoiesis, defining many of the transcriptional factors (TFs) fundamental to that process and their role in inherited Plt disorders. He pioneered the use of induced pluripotent stem cells (iPSCs) to study megakaryocyte (Meg) biology and demonstrated the first strategy for genetically correcting the defect in GT and in Paris-Trousseau syndrome. Dr. Poncz proposes to pursue new insights into the molecular basis of the thrombocytopenia observed in RUNX1 haploinsufficiency, and how this intervention might decrease the risk of leukemic transformation in affected patients. This interest in megakaryopoiesis also lead to Dr. Poncz’s contribution to understanding where Plts are released, showing that infused Megs release Plts in the lungs. The resulting Plts are much more physiologic than any ex vivo-generated Plts released from in vitro-grown Megs to date. These studies supported a potential pulmonary site for a portion of thrombopoiesis with subsequent studies by others providing in situ-support for this model. Dr. Poncz now shows that the lung microcapillary bed is unique in being able to release Plts. Proposed studies will further our understanding of what makes the pulmonary bed unique for thrombopoiesis, and such insights may have clinical application in Plt transfusions. Dr. Poncz also proposed that Plts could store ectopic proteins in a granules, releasing them in a targeted, potent fashion at sites of vascular injury. He proposes advancing the use of Plt-targeted therapeutics by a novel new mechanism for loading such proteins into Plts to treat hemophilia A patients with inhibitors with Factor VIII variants and for use as a thromboprophylaxis agent with urokinase variants. Dr. Poncz has also advanced our understanding of the molecular basis of prothrombotic heparin-induced thrombocytopenia (HIT). His HIT-like antibody KKO and murine model for HIT are widely used in the field and both were used in his recent advances in understanding the role of neutrophil extracellular traps (NETs) in HIT. He now proposes that polyanions like NETs underlie the prothrombotic nature of HIT, and will test this in this R35. Moreover, he believes that these new insights have implications in the care of other thromboinflammatory diseases where NETs have an important role, and proposes use of PF4 and Fc-modified KKO in the treatment of sepsis and sickle cell disease. Support from this R35 OIA mechanism will also provide Dr. Poncz with the time to pursue his other passion of advancing the career of mentees in areas related to benign hematology.