Proliferation of cardiomyocytes in young infants, future implication in human heart regeneration

Abstract

Background- Human heart is a limited-mitotic organ that responds to injury with limited cell renewal. In young infants, study of the regenerative capacity of cardiomyocytes may provide an important approach for heart regeneration. Methods and results- Human right atrial specimens were obtained during routine surgery for ventricle septal defect(VSD) and were divided into two groups: Young infant group (age, 1-3 months) and Old infant group (age, 4-6 months). Results showed that Ki67 is expressed in proliferating cardiac myocytes, and that the number of Ki67-positive cells in young infant group is significantly higher than old group. The Notch pathway was found to regulate cardiomyocyte proliferation and apoptosis during development. Current data showed that NICD expression is significantly higher in young age group and NICD was mainly expressed in cardiomyocyte nuclei. Conclusions- Proliferating cardiac myocytes are more abundant in the young infant period (<3 months) and the Notch pathway is conserved in humans. Further understanding of their proliferative ability at different ages may provide novel therapeutic targets that can be used to enhance cardiovascular regenerative capacity.