Two mechanisms of cardiac stem cell-mediated cardiomyogenesis in the adult mammalian heart include formation of colonies and cell-in-cell structures
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Galina B. Belostotskaya1,2, Irina V. Nerubatskaya1,2 and Michael M. Galagudza3
1Sechenov Institute of Evolutionary Physiology and Biochemistry of Russian Academy of Sciences, Russian Federation, Saint-Petersburg, Russian Federation
2Almazov National Medical Research Centre, Russian Federation, Saint-Petersburg, Russian Federation
3ITMO University, Russian Federation, Saint-Petersburg, Russian Federation
Galina B. Belostotskaya, email: [email protected]
Keywords: cardiac stem cells (CSCs); CSC-derived colony; cell-in-cell structures (CICSs); transitory amplifying cells (TACs); cardiomyogenesis
Abbreviations: CICSs, cell-in-cell structures; CMs, cardiomyocytes; CSCs, cardiac stem cells; TACs, transitory amplifying cells
Received: November 14, 2017 Accepted: August 16, 2018 Published: September 25, 2018
Aims: Because the mechanism of mature cardiomyocyte (CM) development from cardiac stem cells (CSCs) is not fully understood, we explored the involvement of CSCs into two pathways of cardiomyogenesis in adult mammalian heart: (1) via colony formation and (2) by means of intracellular development of CSCs inside CMs followed by the formation of “cell-in-cell structures” (CICSs).
Methods and Results: Using immunostaining and confocal microscopy, we studied the presence of CSC-derived colonies, CICSs and transitory amplifying cells (TACs), released from ruptured CICSs, in a suspension of ex vivo freshly isolated myocardial cells of mammals of different age and species, human including. All subsets of CSCs (c-kit+, Sca-1+ and Isl-1+) were found in mammals of different age. It was shown that c-kit+ and Sca-1+ CSCs produce both colonies and CICSs. However, Isl-1+ CSCs seem to be involved in cardiac growth during first month of age only both through colony formation and CICS generation. In turn, the studies on myocardial cell suspensions of adult C57/bl6N mice, one-year-old bull and 45-year-old woman not only confirmed the involvement of c-kit+ and Sca-1+ CSCs in both mechanisms of cardiomyogenesis, but also showed that Isl-1+ colonies are present in the myocardium of adult mice and rarely in human.
Conclusions: The presence of CSC-derived colonies, CICSs and TACs in all experimental specimens of myocardium proved our previous hypothesis about two pathways that generate new CMs in adult heart. Moreover, we suggest that TACs play a central role in self-renewal of myocardium throughout the lifetime of mammals.
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