微粒在急性早幼粒细胞白血病凝血病发病中的作用及机制研究

Although the clinical application of differentiation therapy has made great success in the treatment of acute promyelocytic leukemia (APL), early fatal bleeding remains an unsolved problem which accounts for the main reason of induction failure in APL patients. .The clinical manifestation of both serious bleeding and thrombosis illustrate the complexity of the pathogenesis of coagulopathy in APL. Despite extensive research, the pathogenesis of coagulopathy in APL is still unclear. Microparticles, 0.11μm in diameter, are small membrane vesicles released to circulation by blood cells and vascular endothelial cells during activation or apoptosis. Microparticles derived from different cells types all exert procoagulant activity mediated by phosphatidylserine (PS) and carry some basic substances derived from their origin cells. Also, the biological activity of microparticles is often significantly higher than that of the cells they come from. .According to these problems and background knowledge, our project aims to observe the roles of microparticles derived from APL cells and the procoagulant or profibrinolytic activating factors resided on these microparticles in the pathogenesis of coagulopathy in APL, and the effects of different induction therapies, chemotherapeutic drugs or differentiation agents on these microparticles and their procoagulant or profibrinolytic activating factors. To carry out this study, microparticles are obtained from patients who undergo different induction therapies at different time points or from primary bone marrow APL cells which are treated by different drugs in vitro at different time points, the expressions and activities of five procoagulant or profibrinolytic activating factors, which are highly expressed in APL cells, PS exposure and the functional state of these microparticles, will be dynamically monitored. .Further study of the pathogenesis of coagulopathy in APL can provide clues and help for deep understanding of clinical manifestations, guiding clinical treatment as well as judging prognosis, and establishing theoretical basis for exploring new treatment.

尽管分化治疗药物的临床应用使得急性早幼粒细胞白血病(APL)的治疗取得巨大的成功，早期致死性出血仍是一个无法解决的难题而成为APL诱导治疗失败最主要的原因。.目前APL凝血病的发病机制仍不十分清楚。血浆中各种细胞来源微粒均具有磷脂酰丝氨酸(PS)介导的促凝活性，携带有其来源细胞的一些基本物质，而且其生物学活性常显著高于其来源细胞。.基于上述问题和背景，分别以APL患者不同方法诱导治疗前后血浆中APL细胞来源微粒和骨髓原代APL细胞经不同药物处理前后所释放的微粒为研究对象，对在APL细胞中异常高表达的5种促凝促纤溶因子及PS在这些微粒中的表达及活性进行动态监测，观察APL来源微粒及其表面促凝促纤溶因子在APL凝血病发病中的作用及诱导治疗药物对其产生的影响。.对本病发病机制的深入研究，可以为临床医生深入认识疾病的临床表现、指导临床治疗乃至判断预后提供线索和帮助，为探索新的治疗方法奠定理论基础。

尽管分化治疗药物的临床应用使得急性早幼粒细胞白血病(APL)的治疗取得巨大的成功，早期致死性出血仍是一个无法解决的难题而成为APL诱导治疗失败最主要的原因。尽管进行了大量研究，APL凝血病的发病机制目前仍不十分清楚。.APL患者初发时血浆TF含量高于正常人群水平，ATO诱导治疗0-2周时，血浆TF含量迅速降低，之后降低缓慢，达血液学缓解时接近正常。正常人群血浆中微粒由于携带有凝血因子而具有明显促凝活性，微粒表面不表达TF，因此无启动凝血活性。APL患者初发时血浆中微粒表面表达大量TF，表现出明显的启动凝血活性；ATO诱导治疗2周时，微粒表面表达的TF水平已接近血浆水平，仍存在少量的启动凝血活性。.正常人群血浆中的纤溶相关蛋白，包括tPA，uPA，uPAR，Annexin II，Pg，PAI-1，PAP，绝大部分都由外泌体携带，只有少量游离在血浆中。但是在有Fb存在时，外泌体并无促纤溶活性，血浆促纤溶活性主要来源于游离的tPA和uPA，而外泌体的功能是向Fb存在部位快速运输和释放大量tPA和uPA，因此对游离tPA和uP A的促纤溶作用起协同作用。.APL患者初发时血浆促纤溶活性与正常人平均水平相当。ATO诱导治疗0-3周时，血浆促纤溶活性逐渐降低并达最低点，之后逐渐恢复。APL患者纤溶亢进为继发性，凝血紊乱根源在于活性TF持续存在引起凝血通路的持续激活，凝血因子大量持续消耗，Fb持续形成，继发性纤溶亢进持续存在，直至达完全血液学缓解时尚有部分指标未能完全恢复至正常。微粒和外泌体在凝血紊乱持续存在中发挥了重要作用。.本课题的研究具有重要的科学意义。首先，世界范围内首先发现正常人群血浆中外泌体在凝血、纤溶中发挥重要作用，并对其发挥作用机制进行了初步探索，其研究方法会成为突破体液中外泌体作用研究的瓶颈的金钥匙；其研究结果会为生理性及各种病理性凝血纤溶机制的研究开拓新的思路。其次，APL凝血紊乱发病机制的阐明，不仅可以为未来的研究提供新方向，而且可以为临床医生深入认识疾病的临床表现、指导临床治疗乃至判断疾病转归提供帮助，为探索新的临床治疗方法，即应用抗凝抗纤溶药物治疗APL凝血病提供充足的理论依据以及必要的临床监测指标，因此，临床意义深远。