Objective: To investigate the molecular mechanism underlying the differentiation of human umbilical cord-derived mesenchymal stem cells (hUCMSCs) into myocardial cells induced by 5-azacytidine (5-aza), and to explore the expression and significance of DLL4-Notch signaling in this process.
Materials and methods: hUCMSCs were isolated and purified from the umbilical cords of normal or cesarean term deliveries under sterile conditions. After treatment with 5-aza for 24 h, hUCMSCs was continued to culture, the expression of GATA4 and NKx2.5 at 4 weeks after induction, DLL4 and Notch1 mRNA at 1d, 3d, 5d, 7d after induction were detected. The expression of cardiac troponin I (cTnI) after 4 weeks was determined by immunocytochemistry.
Results: hUCMSCs treated with 5-aza were stained positively for cTnI 4 weeks after induction. The expression of Notch1 and DLL4 mRNA in the 5-aza-induced group was stable and significantly higher than that in the control group (mean Ct value for the Notch1 gene: 0.51 ± 0.21 in the 5-aza-induced group vs. 7.85 ± 0.35 in the control group; mean Ct value for the DLL4 gene: 1.60 ± 0.49 in the 5-aza-induced group vs. 12.42 ± 0.73 in the control group). Similar results were observed for Nkx2.5 and GATA4 genes. The expressions of Nkx2.5 and GATA4 mRNA in the 5-aza group were 4.72 ± 0.58 and 3.76 ± 0.06 times higher than that in the control group, respectively, with statistical significance.
Conclusions: hUCMSCs can be differentiated into myocardial cells by 5-aza induction in vitro. 5-Aza may affect this process by regulating the expression of GATA4 and Nkx2.5 genes. The DLL4-Notch signal pathway may be involved in this process.