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 immunofluorescence at 7, 14 and 21 days post-infection, respectively. Expression of cardiac-related genes-including Nkx2.5, Gata-4, TNNT2, MEF2c, ISL-1, FOXH1, KDR, αMHC and α-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, ISL-1, FOXH1, KDR, αMHC and α-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 hUCMSCs 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.