PDF(Pubmed)
Abstract：
Rationale: Extracellular vesicles (EVs) are thought to mediate intercellular communication during development and disease. Yet, biological insight to intercellular EV transfer remains elusive, also in the heart, and is technically challenging to demonstrate. Here, we aimed to investigate biological transfer of cardiomyocyte-derived EVs in the neonatal heart. Methods: We exploited CD9 as a marker of EVs, and generated two lines of cardiomyocyte specific EV reporter mice: Tnnt2-Cre; double-floxed inverted CD9/EGFP and αMHC-MerCreMer; double-floxed inverted CD9/EGFP. The two mouse lines were utilized to determine whether developing cardiomyocytes transfer EVs to other cardiac cells (non-myocytes and cardiomyocytes) in vitro and in vivo and investigate the intercellular transport pathway of cardiomyocyte-derived EVs. Results: Genetic tagging of cardiomyocytes was confirmed in both reporter mouse lines and proof of concept in the postnatal heart showed that, a fraction of EGFP+/MYH1- non-myocytes exist firmly demonstrating in vivo cardiomyocyte-derived EV transfer. However, two sets of direct and indirect EGFP +/- cardiac cell co-cultures showed that cardiomyocyte-derived EGFP+ EV transfer requires cell-cell contact and that uptake of EGFP+ EVs from the medium is limited. The same was observed when co-cultiring with mouse macrophages. Further mechanistic insight showed that cardiomyocyte EV transfer occurs through type I tunneling nanotubes. Conclusion: While the current notion assumes that EVs are transferred through secretion to the surroundings, our data show that cardiomyocyte-derived EV transfer in the developing heart occurs through nanotubes between neighboring cells. Whether these data are fundamental and relate to adult hearts and other organs remains to be determined, but they imply that the normal developmental process of EV transfer goes through cell-cell contact rather than through the extracellular compartment.
摘要：
原理：细胞外囊泡（EV）被认为在发育和疾病过程中介导细胞间的通讯。然而，细胞间EV转移的生物学见解仍然难以捉摸，也在心里，并且在技术上具有挑战性。这里,我们的目的是研究心肌细胞来源的EV在新生儿心脏中的生物学转移。方法：我们利用CD9作为电动汽车的标志物，并产生了两系心肌细胞特异性EV报告小鼠：Tnnt2-Cre；双联反向CD9/EGFP和αMHC-MerCreMer；双联反向CD9/EGFP。两个小鼠系用于确定发育中的心肌细胞是否在体外和体内将EV转移到其他心脏细胞（非肌细胞和心肌细胞），并研究心肌细胞衍生的EV的细胞间转运途径。结果：在报告小鼠品系和出生后心脏的概念证明中都证实了心肌细胞的遗传标记，EGFP+/MYH1-非肌细胞的一部分牢固地存在，表明体内心肌细胞来源的EV转移。然而,两组直接和间接EGFP+/-心肌细胞共培养结果显示,心肌细胞衍生的EGFP+EV转移需要细胞-细胞接触,且从培养基中摄取EGFP+EV是有限的.当与小鼠巨噬细胞共培养时观察到相同的情况。进一步的机械见解表明，心肌细胞EV转移通过I型隧道纳米管发生。结论：虽然当前的概念假设电动汽车通过分泌物转移到周围环境中，我们的数据显示,在发育中的心脏中,心肌细胞衍生的EV转移通过相邻细胞之间的纳米管发生.这些数据是否是基本的，是否与成人心脏和其他器官有关还有待确定，但它们暗示EV转移的正常发育过程是通过细胞-细胞接触而不是通过细胞外室。
