华中科技大学李秋柏小组发现，脐带间充质干细胞衍生的大型细胞外囊泡以剂量和组织因子依赖性方式诱发小鼠致命性肺血栓栓塞症。相关论文于2024年6月24日在线发表在《中国药理学报》杂志上。

研究人员系统地揭示了从人脐带间充质干细胞（MSC）中提取的大型细胞外囊泡（UC-EV）在体外和体内的促凝活性。UC-EV从细胞培养上清液中分离出来。小鼠尾静脉注射100μL PBS中的UC-EV（0.125、0.25、0.5、1、2、4μg/g体重）。在注射后的30分钟内监测其行为和死亡率。研究人员发现，这些UC-EV以剂量和组织因子依赖的方式激活了凝血功能。加入组织因子通路抑制剂可抑制UC-EV在体外诱导的凝血。值得注意的是，静脉注射高剂量的UC-EV（1μg/g体重或更高）会导致肺组织多血栓形成、血小板和纤维蛋白原耗竭、凝血酶原和活化部分凝血活酶时间延长，从而导致快速死亡。

重要的是，研究人员证明了通过降低输注速度或预先注射肝素（一种已知的抗凝剂）可以预防UC-EV引起的肺血栓栓塞。总之，这项研究阐明了大型UC-EV的促凝特性和机制，详细说明了静脉注射过程中相关的凝血风险，设定了静脉注射剂量的安全上限，并提供了有效的策略，在需要大剂量大型UC-EV以达到最佳治疗效果时，防止这种致命风险的发生，对基于大型UC-EV和其他MSC-EV疗法的开发和应用具有重要意义。

据了解，MSC-EV与MSC疗法相比具有明显的优势。但是MSC-EV具有很强的促凝血特性，会带来血栓栓塞的潜在风险，而这一问题目前仍未得到充分探讨。

附：英文原文

Title: Lethal pulmonary thromboembolism in mice induced by intravenous human umbilical cord mesenchymal stem cell-derived large extracellular vesicles in a dose- and tissue factor-dependent manner

Author: Yang, Bian-lei, Long, Yao-ying, Lei, Qian, Gao, Fei, Ren, Wen-xiang, Cao, Yu-lin, Wu, Di, Xu, Liu-yue, Qu, Jiao, Li, He, Yu, Ya-li, Zhang, An-yuan, Wang, Shan, Wang, Hong-xiang, Chen, Zhi-chao, Li, Qiu-bai

Issue&Volume: 2024-06-24

Abstract: Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have obvious advantages over MSC therapy. But the strong procoagulant properties of MSC-EVs pose a potential risk of thromboembolism, an issue that remains insufficiently explored. In this study, we systematically investigated the procoagulant activity of large EVs derived from human umbilical cord MSCs (UC-EVs) both in vitro and in vivo. UC-EVs were isolated from cell culture supernatants. Mice were injected with UC-EVs (0.125, 0.25, 0.5, 1, 2, 4μg/g body weight) in 100μL PBS via the tail vein. Behavior and mortality were monitored for 30min after injection. We showed that these UC-EVs activated coagulation in a dose- and tissue factor-dependent manner. UC-EVs-induced coagulation in vitro could be inhibited by addition of tissue factor pathway inhibitor. Notably, intravenous administration of high doses of the UC-EVs (1μg/g body weight or higher) led to rapid mortality due to multiple thrombus formations in lung tissue, platelets, and fibrinogen depletion, and prolonged prothrombin and activated partial thromboplastin times. Importantly, we demonstrated that pulmonary thromboembolism induced by the UC-EVs could be prevented by either reducing the infusion rate or by pre-injection of heparin, a known anticoagulant. In conclusion, this study elucidates the procoagulant characteristics and mechanisms of large UC-EVs, details the associated coagulation risk during intravenous delivery, sets a safe upper limit for intravenous dose, and offers effective strategies to prevent such mortal risks when high doses of large UC-EVs are needed for optimal therapeutic effects, with implications for the development and application of large UC-EV-based as well as other MSC-EV-based therapies.

DOI: 10.1038/s41401-024-01327-3

Source: https://www.nature.com/articles/s41401-024-01327-3