辐射诱导骨髓血管内皮细胞损伤对巨核细胞终末分化的影响作用及机制研究

ionizing radiation could result in the failure of megakaryocytopoiesis and low level of platelets. Previous studies mainly focused on the effects of ionizing radiation on megakaryocytes. There were few researches on platelet production disorder caused by the dysfunction of hematopoietic microenviroment. Terminal differentiation of megakaryocytes is closely related to the " vascular niche " composed by endothelial cells. Cytokines secreted by endothelial cells play important roles on megakaryocyte maturation, migration and platelet production. Our previous study found that the adhesion and migration were significantly reduced when megakaryocytes co-cultured with endothelial cells irradiated with a dose of 6Gy. We speculate that ionizing radiation may affect megakaryocyte differentiation that leads to the extension of platelet production through vascular endothelial cells injury, This study aims to investigate the mechanism of the failure of megakaryocyte terminal differentiation and platelet production via analyzing the effects of ionizing radiation on vascular endothelial cells by Transwell coculture , protein chip analysis , RNA interference, Western blot, confocal and flow cytometry analysis.

电离辐射可引起骨髓巨核细胞生成障碍及血小板水平降低。既往研究主要关注电离辐射对巨核细胞的影响，对造血微环境受损导致血小板生成过程受阻缺乏研究。巨核细胞终末分化与血管内皮细胞形成的“血管龛”结构紧密相关。内皮细胞分泌的细胞因子在巨核细胞成熟、迁移和血小板生成过程中发挥着重要作用。前期研究发现，将巨核细胞与6Gy照射后内皮细胞共培养，巨核细胞粘附、迁移能力显著降低。推测电离辐射可能通过损伤骨髓血管内皮细胞影响巨核细胞终末分化，进而导致血小板生成周期延长。本项目拟采用Transwell共培养、蛋白芯片分析、RNA干扰、Western blot、激光共聚焦、流式细胞分析等技术，并通过清髓后造血干细胞移植小鼠模型进行在体验证，分析电离辐射对血管内皮细胞的损伤作用，探讨其引起巨核细胞终末分化及血小板生成障碍的机制.

血小板减少症是放射损伤后出血和死亡的重要原因，既往研究主要关注电离辐射对巨核细胞的影响，对造血微环境受损导致血小板生成过程受阻缺乏研究。巨核细胞终末分化与血管内皮细胞形成的“血管龛”结构紧密相关，内皮细胞分泌的细胞因子在巨核细胞成熟、迁移和血小板生成过程中发挥着重要作用。本课题将巨核细胞与电离辐射损伤后的内皮细胞共培养，发现巨核细胞粘附、迁移能力显著降低。实验证实，电离辐射导致血管内皮细胞形态学改变加速细胞凋亡，辐照后VEGF表达和分泌显著减少，而VEGF的缺失促进了巨核细胞粘附、迁移和血小板产板减弱。体外实验实，VEGF能够促进放射损伤小鼠的血小板恢复，通过HE染色观察给予VEFG处理组巨核细胞与血管龛的距离远小于对照组。这些发现从造血微环境的角度揭示了放射损伤后血小板恢复缓慢的原因，希望能为血小板减少症发病机制研究提供新的见解。