DNA methyltransferase inhibitor 5-azacytidine in high dose promotes ultrastructural maturation of cardiomyocyte.

Background: The adult human heart muscle cells, cardiomyocytes are not capable of regenerate after injury. Stem cells are a powerful means for future regenerative medicine because of their capacity for self-renewal and multipotency. Several studies have reported the cardiogenic potential in human adipose tissue-derived stem cells (ADSCs) differentiation, but there is still no efficient protocol for the induction of cardiac differentiation by 5-azacytidine (5-Aza). The present study involves characterization and mainly, the ultrastructure of ADSCs derived cardiomyocyte-like cells.

Methods: The cultured ADSCs were treated with 50 µM 5-Aza for 24 hours, followed by a 10-week extension. At different time points, cardiomyocyte-like cells were assessed by qRT-PCR and were evaluated by transmission electron microscopy at 10^th week.

Results: The expression of cardiac-specific markers entailing cardiac troponin I (cTnI), connexin 43, myosin light chain-2v (Mlc-2v), increased over 10 weeks and the highest expression was at 10^th week. The expression of the β-myosin heavy chain (β-MHC) increased significantly over 5 weeks and then decreased. At the ultrastructural level myofibrils, transverse tubules (T-tubules), sarcoplasmic reticular membrane, and intercalated discs were present.

Conclusions: These data suggest that treatment with 5-Aza in high dose could promote differentiation of ADSCs into cardiomyocyte-like cells. These differentiated cells could be used for regeneration of damaged cardiomyocytes with the 3D scaffold for delivery of the cells.