c-kit Haploinsufficiency impairs adult cardiac stem cell growth, myogenicity and myocardial regeneration

Abstract

An overdose of Isoproterenol (ISO) causes acute cardiomyocyte (CM) dropout and activates the resident cardiac c-kit pos stem/progenitor cells (CSCs) generating a burst of new CM formation that replaces those lost to ISO. Recently, unsuccessful attempts to reproduce these findings using c-kit Cre knock-in (KI) mouse models were reported. We tested whether c-kit haploinsufficiency in c-kit Cre KI mice was the cause of the discrepant results in response to ISO. Male C57BL/6J wild-type (wt) mice and c-kit Cre KI mice were given a single dose of ISO (200 and/or 400 mg/Kg s.c.). CM formation was measured with different doses and duration of BrdU or EdU. We compared the myogenic and regenerative potential of the c-kit Cre CSCs with wtCSCs. Acute ISO overdose causes LV dysfunction with dose-dependent CM death by necrosis and apoptosis, whose intensity follows a basal-apical and epicardium to sub-endocardium gradient, with the most severe damage confined to the apical sub-endocardium. The damage triggers significant new CM formation mainly in the apical sub-endocardial layer. c-kit haploinsufficiency caused by c-kit Cre KIs severely affects CSCs myogenic potential. c-kit Cre KI mice post-ISO fail to respond with CSC activation and show reduced CM formation and suffer chronic cardiac dysfunction. Transplantation of wtCSCs rescued the defective regenerative cardiac phenotype of c-kit Cre KI mice. Furthermore, BAC-mediated transgenesis of a single c-kit gene copy normalized the functional diploid c-kit content of c-kit Cre KI CSCs and fully restored their regenerative competence. Overall, these data show that c-kit haploinsufficiency impairs the endogenous cardioregenerative response after injury affecting CSC activation and CM replacement. Repopulation of c-kit haploinsufficient myocardial tissue with wtCSCs as well c-kit gene deficit correction of haploinsufficient CSCs restores CM replacement and functional cardiac repair. Thus, adult neo-cardiomyogenesis depends on and requires a diploid level of c-kit.

Pressure overload by suprarenal aortic constriction in mice leads to left ventricular hypertrophy without c-Kit expression in cardiomyocytes

“…One lineage-tracing study reported a modest increase in c-Kit-expressing cardiomyocytes following TAC-induced PO, although the increase was below clinically-relevant levels 45 . However, genetic lineage-tracing Kit-Cre models that result in haploinsufficiency of the c-Kit gene have been questioned, as reviewed 46 – 49 . These may be addressed in the future by using a dual recombination system 48 .…”

Differences in Mitochondrial Membrane Potential Identify Distinct Populations of Human Cardiac Mesenchymal Progenitor Cells

“…Thus, the expression of c-kit (a type III receptor tyrosine kinase) seems necessary. Indeed, c-kit haploinsufficiency in c-kit-deficient mice induced a falling myocardial repair after injury [ 33 ]. Furthermore, change of c-kit gene for Cre Recombinase expression in Cre/Lox genetic fate map animal models induced a detrimental c-kit haploinsufficiency that avoids efficient labeling of true CSCs and affects the regenerative capacity of these cells [ 34 ].…”

The Microenvironment of Decellularized Extracellular Matrix from Heart Failure Myocardium Alters the Balance between Angiogenic and Fibrotic Signals from Stromal Primitive Cells

“…Among resident stromal cells, a population of cardiac primitive cells (CPCs) is traceable in the adult human heart by means of different criteria [12][13][14][15][16], which can mediate CCT benefits through multiple biological mechanisms, including direct regeneration and, more importantly, angiogenic, anti-fibrotic, cytoprotective, and anti-inflammatory effects [17,18]. Multiple pathways and signals have been reported to affect the phenotype of CPCs [19][20][21][22][23][24][25]. Biological and functional changes occurring during cardiac adverse remodeling affect both ECM composition and architecture.…”