Overexpression of Pygo2 Increases Differentiation of Human Umbilical Cord Mesenchymal Stem Cells into Cardiomyocyte-like Cells

Background: Our previous studies have shown that Pygo (Pygopus) in Drosophila plays a critical role in adult heart function that is likely conserved in mammals. However, its role in the differentiation of human umbilical cord mesenchymal stem cells (hUC-MSCs) into cardiomyocytes remains unknown. Objective: To investigate the role of pygo2 in the differentiation of hUC-MSCs into cardiomyocytes. Methods: Third passage hUC-MSCs were divided into two groups: a p+ group infected with the GV492-pygo2 virus and a p- group infected with the GV492 virus. After infection and 3 or 21 days of incubation, Quantitative real-time PCR (qRT-PCR) was performed to detect pluripotency markers, including OCT-4 and SOX2. Nkx2.5, Gata-4 and cTnT were detected by immuno-fluorescence at 7, 14 and 21 days post-infection, respectively. Expression of cardiac-related genes-including Nkx2.5, Gata-4, TNNT2, MEF2c, 1SL-1, FOXH1, KDR, aMHC and a-Actin-were analyzed by qRT-PCR following transfection with the virus at one, two and three weeks. Results: After three days of incubation, there were no significant changes in the expression of the pluripotency stem cell markers OCT-4 and SOX2 in the p+ group hUC-MSCs relative to controls (OCT-4: 1.03 +/- 0.096 VS 1, P > 0.05, SOX2: 1.071 +/- 0.189 VS 1, P > 0.05); however, after 21 days, significant decreases were observed (OCT-4: 0.164 +/- 0.098 VS 1, P < 0.01, SOX2: 0.209 +/- 0.109 VS 1, P < 0.001). Seven days following incubation, expression of mesoderm specialisation markers, such as Nkx2.5, Gata-4, MEF2c and KDR, were increased; at 14 days following incubation, expression of cardiac genes, such as Nkx2.5, Gata-4, TNNT2, MEF2c, 1SL-1, FOXH1, KDR, aMHC and a-Actin, were significantly upregulated in the p+ group relative to the p- group (P < 0.05). Taken together, these findings suggest that overexpression of pygo2 results in more hUC-MSCs gradually differentiating into cardiomyocyte-like cells. Conclusion: We are the first to show that overexpression of pygo2 significantly enhances the expression of cardiac-genic genes, including Nkx2.5 and Gata-4, and promotes the differentiation of hUC-MSCs into cardiomyocyte-like cells.