Identification of cardiac stem cells within mature cardiac myocytes.
Cardiac stem cells are described in a number of mammalian species including humans. Cardiac stem cell clusters consisting of both lineage-negative and partially committed cells are generally identified between contracting cardiac myocytes. In the present study, c-kit(+), Sca(+), and Isl1(+) stem cells were revealed to be located inside the sarcoplasm of cardiac myocytes in myocardial cell cultures derived from newborn, 20-, and 40-day-old rats. Intracellularly localized cardiac stem cells had a coating or capsule with a few pores that opened into the host cell sarcoplasm. The similar structures were also identified in the suspension of freshly isolated myocardial cells (ex vivo) of 20- and 40-day-old rats. The results from this study provide direct evidence for the replicative division of encapsulated stem cells, followed by their partial cardiomyogenic differentiation. The latter is substantiated by the release of multiple transient amplifying cells following the capsule rupture. In conclusion, functional cardiac stem cells can reside not only exterior to but also within cardiomyocytes.
a Centre of Cytoanalysis; Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences ; St. Petersburg , Russia.|b Institute of Experimental Medicine; North-West Federal Medical Research Centre ; St. Petersburg , Russia.
Galina
G
Belostotskaya
c First Pavlov State Medical University of St. Petersburg ; St. Petersburg , Russia.
Alexey
A
Nevorotin
b Institute of Experimental Medicine; North-West Federal Medical Research Centre ; St. Petersburg , Russia.|d ITMO University ; St. Petersburg , Russia.
Michael
M
Galagudza
D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000166:cytology*
cell-in-cell structure; differentiation; mature cardiac myocytes; primary culture of myocardial cells; proliferation; resident cardiac stem cells; transitory amplifying cells