The Effect of Human Cardiac Myocyte-Derived Conditioned Medium on Differentiation of Mesenchymal Stem Cells

Background: Mesenchymal stem cells (MSC) possess specific properties that make them good candidates for cell therapy, especially in organs like the heart with limited regeneration capacity. Generating cardiac myocytes in vitro is an important step toward restoring lost function in cardiovascular diseases. 
Objectives: In this study, we investigated the potential of a human cardiomyocytes-conditioned medium to induce cardiogenic differentiation (indicated by GATA4 expression) of rat bone marrow MSCs.
Methods: Rat bone marrow MSCs were extracted and cultured. They were characterized based on morphology, adipogenic and cardiogenic differentiation potential, and expression of mesenchymal markers. MSCs were exposed to the conditioned medium (case group) or normal saline for 1, 3, and 7 days. The growth curve, population doubling time, and GATA4 expression were compared between the groups. 
Results: MSCs of the case group showed accelerated growth with a lower population doubling time. GATA4 expression as a specific cardiac marker was significantly higher in the case group compared with the controls on day 1. By days 3 and 7, GATA4 expression remained higher, albeit the difference with the control group became less.
Conclusions: Our findings demonstrated that possible cardiac myocyte-derived factors instigate the proliferation and cardiogenic differentiation of MSCs. This study provides a novel bone marrow MSC model for investigating early cardiomyocyte generation, which can open new avenues in the treatment of heart diseases.