Abstract:

BACKGROUND: Human umbilical cord mesenchymal stem cells possess multi-differentiation potential. There are few studies describing whether human umbilical cord mesenchymal stem cells can be induced to differentiate into cardiomyocytes .
OBJECTIVE: To investigate cardiac troponin I expression in human umbilical cord mesenchymal stem cells after 5-azacytidine induction in vitro.
METHODS: Passage 2 human umbilical cord mesenchymal stem cells were digested, centrifuged and deposited. Cell suspension was prepared and cell concentration was adjusted to be 2×10⁷/L. Then cells were cultured for 24 hours after addition of various concentrations of 5-azacytidine (80, 40, 20, 10, 5, 2.5, 0 μmol/L). After removal of 5-azacytidine, cells were cultured for another 4 weeks.
RESULTS AND CONCLUSION: After treatment with 5-azacytidine for 24 hours, some cells died in each group, and typical fusiform appearance turned into stick-like or column-like appearance, especially in the 40 and 80 μmol/L 5-azacytidine groups. Immunohistochemical staining results showed that cardiac troponin I expression was detected in human umbilical cord mesenchymal stem cells in 5, 10, 20, 40, 80 μmol/L 5-azacytidine groups after induction for 2 weeks, but it was not detected in the control and 2.5 μmol/L 5-azacytidine groups. Five high-fold fields were selected for cell counting. The number of cardiomyocytes was not significantly different between 80, 40, 20, 10 μmol/L 5-azacytidine groups, but it was significantly higher compared to that in the 5 μmol/L 5-azacytidine group. After 5-azacytidine treatment for 4 weeks, typical sarcomeres and cardiac atrium particles were observed in some human umbilical cord mesenchymal stem cells. Such changes were not observed in the control group in which 5-azacytidine induction was not used. These findings suggest that human umbilical cord mesenchymal stem cells were induced to cardiomyocyte-like cells by 5-azacytidine.

Key words: stem cells, stem cell culture and differentiation, umbilical cord mesenchymal stem cells, 5-azacytidine, immunohistochemistry, cardiomyocyte, cardiac troponin I, stem cell photographs-containing paper