Cellular and Molecular Cardiology Laboratory, Cardiocentro Ticino Foundation and Swiss Institute for Regenerative Medicine (SIRM), via Tesserete 48, 6900 Lugano, Switzerland.
Institute of Life Sciences, Scuola Superiore Sant'Anna and UOS Anesthesiology, Fondazione Toscana G. Monasterio, Pisa, Italy.
Cardiovasc Res. 2018 Jun 1;114(7):992-1005. doi: 10.1093/cvr/cvy055.
Cell therapy trials using cardiac-resident progenitor cells (CPCs) and bone marrow-derived mesenchymal stem/progenitor cells (BMCs) in patients after myocardial infarction have provided encouraging results. Exosomes, nanosized extracellular vesicles of endosomal origin, figure prominently in the bioactivities of these cells. However, a head-to-head comparison of exosomes from the two cell types has not been performed yet.
CPCs and BMCs were derived from cardiac atrial appendage specimens and sternal bone marrow, respectively, from patients (n = 20; age, 69.9 ± 10.9) undergoing heart surgery for aortic valve disease and/or coronary artery disease. Vesicles were purified from cell conditioned media by centrifugation/filtration and ultracentrifugation. Vesicle preparations were predominantly composed of exosomes based on particle size and marker expression (CD9, CD63, CD81, Alix, and TSG-101). CPC-secreted exosomes prevented staurosporine-induced cardiomyocyte apoptosis more effectively than BMC-secreted exosomes. In vivo, CPC-secreted exosomes reduced scar size and improved ventricular function after permanent coronary occlusion in rats more efficiently than BMC-secreted exosomes. Both types of exosomes stimulated blood vessel formation. CPC-secreted exosomes, but not BMC-derived exosomes, enhanced ventricular function after ischaemia/reperfusion. Proteomics profiling identified pregnancy-associated plasma protein-A (PAPP-A) as one of the most highly enriched proteins in CPC vs. BMC exosomes. The active form of PAPP-A was detected on CPC exosome surfaces. These vesicles released insulin-like growth factor-1 (IGF-1) via proteolytic cleavage of IGF-binding protein-4 (IGFBP-4), resulting in IGF-1 receptor activation, intracellular Akt and ERK1/2 phosphorylation, decreased caspase activation, and reduced cardiomyocyte apoptosis. PAPP-A knockdown prevented CPC exosome-mediated cardioprotection both in vitro and in vivo.
These results suggest that CPC-secreted exosomes may be more cardioprotective than BMC-secreted exosomes, and that PAPP-A-mediated IGF-1 release may explain the benefit. They illustrate a general mechanism whereby exosomes may function via an active protease on their surface, which releases a ligand in proximity to the transmembrane receptor bound by the ligand.
将心脏驻留祖细胞（CPCs）和骨髓来源的间充质干细胞/祖细胞（BMCs）用于心肌梗死后患者的细胞治疗试验已取得令人鼓舞的结果。外泌体是源自内体的纳米级细胞外囊泡，在这些细胞的生物活性中起着重要作用。然而，两种细胞类型的外泌体还没有进行过直接比较。
从接受心脏主动脉瓣疾病和/或冠状动脉疾病手术的患者（n=20；年龄 69.9±10.9 岁）的心脏心房附件标本和胸骨骨髓中分别获得 CPCs 和 BMCs。通过离心/过滤和超速离心从细胞条件培养基中纯化囊泡。囊泡制剂主要基于粒径和标志物表达（CD9、CD63、CD81、Alix 和 TSG-101）由外泌体组成。CPC 分泌的外泌体比 BMC 分泌的外泌体更有效地防止 staurosporine 诱导的心肌细胞凋亡。在体内，CPC 分泌的外泌体在大鼠永久性冠状动脉闭塞后比 BMC 分泌的外泌体更有效地减少疤痕大小并改善心室功能。两种类型的外泌体都刺激血管形成。CPC 分泌的外泌体，但不是 BMC 衍生的外泌体，在缺血/再灌注后增强心室功能。蛋白质组学分析鉴定出妊娠相关血浆蛋白-A（PAPP-A）是 CPC 与 BMC 外泌体相比最丰富的蛋白质之一。在 CPC 外泌体表面检测到 PAPP-A 的活性形式。这些囊泡通过蛋白水解切割 IGF 结合蛋白-4（IGFBP-4）释放胰岛素样生长因子-1（IGF-1），导致 IGF-1 受体激活、细胞内 Akt 和 ERK1/2 磷酸化、 caspase 激活减少和心肌细胞凋亡减少。PAPP-A 敲低在体外和体内均阻止了 CPC 外泌体介导的心脏保护作用。
这些结果表明，CPC 分泌的外泌体可能比 BMC 分泌的外泌体更具心脏保护作用，而 PAPP-A 介导的 IGF-1 释放可能解释了这种益处。它们说明了一种普遍的机制，即外泌体可以通过其表面上的活性蛋白酶发挥作用，该蛋白酶释放配体，使其靠近配体结合的跨膜受体。
