Hematology Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA.
Br J Haematol. 2014 Apr;165(2):227-36. doi: 10.1111/bjh.12758. Epub 2014 Feb 6.
Platelets are essential for haemostasis, and thrombocytopenia (platelet counts <150 × 10(9) /l) is a major clinical problem encountered across a number of conditions, including immune thrombocytopenic purpura, myelodysplastic syndromes, chemotherapy, aplastic anaemia, human immunodeficiency virus infection, complications during pregnancy and delivery, and surgery. Circulating blood platelets are specialized cells that function to prevent bleeding and minimize blood vessel injury. Platelets circulate in their quiescent form, and upon stimulation, activate to release their granule contents and spread on the affected tissue to create a physical barrier that prevents blood loss. The current model of platelet formation states that large progenitor cells in the bone marrow, called megakaryocytes, release platelets by extending long, branching processes, designated proplatelets, into sinusoidal blood vessels. This review will focus on different factors that impact megakaryocyte development, proplatelet formation and platelet release. It will highlight recent studies on thrombopoeitin-dependent megakaryocyte maturation, endomitosis and granule formation, cytoskeletal contributions to proplatelet formation, the role of apoptosis, and terminal platelet formation and release.
血小板对于止血至关重要，而血小板减少症（血小板计数<150×10(9)/l）是多种疾病中遇到的主要临床问题，包括免疫性血小板减少性紫癜、骨髓增生异常综合征、化疗、再生障碍性贫血、人类免疫缺陷病毒感染、妊娠和分娩并发症以及手术。循环血液中的血小板是具有特殊功能的细胞，可防止出血并最大限度地减少血管损伤。血小板以静止形式循环，在受到刺激后会激活，释放其颗粒内容物并在受影响的组织上扩散，形成物理屏障，防止失血。目前的血小板形成模型表明，骨髓中的大祖细胞（称为巨核细胞）通过将长而分支的过程（称为前血小板）延伸到窦状血管中，释放血小板。这篇综述将重点介绍影响巨核细胞发育、前血小板形成和血小板释放的不同因素。它将强调关于血小板生成素依赖性巨核细胞成熟、核内有丝分裂和颗粒形成、细胞骨架对前血小板形成的贡献、细胞凋亡的作用以及终末血小板形成和释放的最新研究。
