A Deep Proteome Analysis Identifies the Complete Secretome as the Functional Unit of Human Cardiac Progenitor Cells

Abstract

Rationale Cardiac progenitor cells are an attractive cell type for tissue regeneration but their mechanism for myocardial remodeling is still unclear. Objective This investigation determines how chronological age influences the phenotypic characteristics and the secretome of human cardiac progenitor cells (CPCs), as well as their potential to recover injured myocardium. Methods and Results Adult (aCPCs) and neonatal (nCPCs) cells were derived from patients more than 40 years or less than one month of age, respectively, and their functional potential was determined in a rodent myocardial infarction (MI) model. A more robust in vitro proliferative capacity of nCPCs, compared to aCPCs, correlated with significantly greater myocardial recovery mediated by nCPCs in vivo. Strikingly, a single injection of nCPC-derived total conditioned media (nTCM) was significantly more effective than nCPCs, aCPC-derived TCM (aTCM), or nCPC-derived exosomes in recovering cardiac function, stimulating neovascularization, and promoting myocardial remodeling. High resolution accurate mass spectrometry (HRAMS) with reverse phase liquid chromatography fractionation and mass spectrometry (LC-MS/MS) was employed to identify proteins in the secretome of aCPCs and nCPCs, and literature-based networking software identified specific pathways affected by the secretome of CPCs in the setting of MI. Examining the TCM, we quantified changes in the expression pattern of 804 proteins in nTCM and 513 proteins in aTCM. Literature-based proteomic network analysis identified that 46 and 6 canonical signaling pathways were significantly targeted by nTCM and aTCM, respectively. One leading candidate pathway is heat shock factor-1 (HSF-1), potentially affecting 8 identified pathways for nTCM but none for aTCM. To validate this prediction, we demonstrated that modulation of HSF-1 by knockdown in nCPCs or overexpression in aCPCs significantly altered the quality of their secretome. Conclusions In conclusion, a deep proteomic analysis revealed both detailed and global mechanisms underlying the chronological age-based differences in the ability of CPCs to promote myocardial recovery via the components of their secretome.

Young Hearts Run Free

“…Consistent with this hypothesis, current report by Sharma et al 7 observed nCPCs transplantation post-MI was associated with greater cell retention and functional benefit compared to aCPCs. Furthermore, a recent report using c-kit BAC -EGFP mouse has shown substantial cardiac regeneration in the cryo-injured neonatal hearts, in-part via contribution of c-kit + CPC to cardiomyogenesis and angiogenesis 9 .…”

“…However, as is the case with other adult progenitors, the regenerative potential of CPCs decline with advancement of age, and thus may not result in consistent and long lasting therapeutic effect 6 . On these lines, the current report in Circulation Research by Sharma et al 7 has shown that human neonatal CPCs (nCPCs) outperform human adult CPCs (aCPCs) in functional recovery post- myocardial infarction (MI), effects which are mediated at least in part by heat shock factor-1(HSF-1).…”

“…To further understand the role of paracrine factors in cardiac repair, Sharma et al 7 designed in vitro experiments to investigate whether total conditioned medium (TCM) or exosomes secreted by nCPCs or aCPC modulate angiogenesis and wound healing. Intriguingly, nTCM significantly enhanced angiogenesis and wound healing compared to nCPC exosomes (nExo) or aTCM.…”

“…Interestingly, HSF1 has been shown to be involved in strengthening elderly hearts against stress 14 . Furthermore, Sharma et al 7 asked whether HSF-1, one of the predicted master regulators of HSPs, whose function in the context of CPCs has not been analyzed to date, can regulate the CPC function and as well as its secretome? Interestingly, knockdown of HSP-1 in nCPCs impaired their function and secretome.…”

Stem Cell Therapy in Heart Diseases – Cell Types, Mechanisms and Improvement Strategies

“…neovascularization, reduced apoptosis of endogenous cardiomyocytes, activation of tissue intrinsic progenitor cells or recruitment of cells beneficial for tissue repair [260,287,290]. Beside the donor´s health status, chronological age significantly influences the characteristics of the SC´s secretome and thereby affects their potential to promote myocardial recovery [291][292][293].…”