Proliferative Potential of Cardiomyocytes in Hypertrophic Cardiomyopathy: Correlation with Myocardial Remodeling

Abstract

Proliferating Ki-67⁺ cardiomyocytes were detected in the interventricular septum myocardium of adult patients with hypertrophic cardiomyopathy. In the same patients, the severity of hypertrophy and the degree of cardiomyocyte differentiation were assessed by the content of myofibrils, ultrastructural morphology, and the pattern of connexin 43-containing gap junction distribution. Adult Ki-67⁺ cardiomyocytes containing sarcomeric α-actin (sarc α-act⁺) in the sarcoplasm (diameter 23.9±6.9 μ) were detected in the myocardium of patients with hypertrophic cardiomyopathy; their relative content varied from 2 to 3084 cells per 1 million cardiomyocytes. Small early differentiating Ki-67⁺/sarc α-act⁺ cardiomyocytes with a thin cytoplasm layer (diameter 5.9±1.7 μ) constituted from 3 to 2262 cells per 1 million cardiomyocytes. These cells were found in the myocardium with the most pronounced structural changes: hypertrophy of cardiomyocytes with signs of their partial dedifferentiation.