STEM CELLS PLAY NO CONSIDERABLE ROLE IN CARDIOMYOCYTE REPOPULATION OF ADULT HUMAN HEART
E.V. Baidyuk,1,* A.Ya. Gudkova,2 G.A. Sakuta,1 E.N. Semernin,2 A.V. Stepanov,1 B.N. Kudryavtsev 1
1 Institute of Cytology RAS, St. Petersburg, 194064,
and 2 I.P. Pavlov First St. Petersburg State Medical University, St. Petersburg, 197022;
* e-mail: bay@mail.ru
There are two viewpoints concerning cardiac regeneration. One assumes that the myocardium of an adult human heart has a weak regenerative capacity. According to another,
myocardium can renew at a high rate due to the presence of resident stem cells. This study was aimed to test the role of stem cells in myocardium repopulation in adult humans of
different age by examining the distribution of cardiomyocytes as to their size and ploidy. Cytofluorimetry and interferometry were used to determine the dry weight, volume and ploidy
of myocytes isolated from the left ventricle of the normal heart of 12 men aged 20-30 years (n = 7) and 40-50 years (n = 5). Dry weight of cardiomyocytes made up
6906 ± 182 pg (10-12 g) aged 20-30 years and 9126 ± 263 pg in men aged 40-50 years. There were no cells with an intermediate volume between amplifying and
mature myocytes. The number of candiomyocytes in the left ventricle made up (3.18 ± 0.05) x 109 cells in the age group 20-30 years and (2.06 ± 0.6) x 109
cells in the age group 40-50 years. Most of the myocyte population was represented by mononucleate cells with tetraploid nuclei (41.3 %). Proportion of myocytes of different ploidy
classes did not change in the interval from 20 to 50 years. Our results strongly suggest that stem cells of the heart are not involved in the regeneration of human myocardium during
aging. The function of the aging heart is mostly compensated by the hypertrophy of the remaining myocytes.
Key words:
human heart, cardiomyocyte, ploidy, hypertrophy, aging, stem cell
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