DNA methylation patterns are closely related to the chromatin structure, and its remodeling is considered an important mechanism in the control of gene transcription during cell differentiation. In rodent, several studies have related the possibility that multipotent mesenchymal stromal cells (MSCs)undergo cardiomyogenesis. However, it has not been completely elucidated if human adult stem cell exhibits true differentiation potential for a cardiac lineage. In this study, the action of the DNA methylation inhibitor 5-azacytidine (5-aza) was examined in human adipose tissue pericytes (hATPCs: 3G5+)regarding their possible capacity to induce myocytes in vitro. Real-Time PCR revealed that cells treated with 5-aza presented time-dependent decrease in the mRNA expression of α-cardiac actin (α-CA). At 24 h, this diminution was statistically significant; however, there was not a correlation with the highest level of DNA demethylation at the same period using Methylation-Sensitive High Resolution Melting-PCR (MS-HRM-PCR). An evident increase in the α-CA protein expression was observed by Western blotting in hATPCs treated with 5-aza at 24 h. The mRNA expression of α-SMA(α-smooth actin) also showed a time-dependent decrease after the treatment, however, it was not significant. The ultrastructural analysis showed similar structures such as like-cell junctions, caveolae, and actin myofilaments, which aligned in parallel. These phenotypic alterations were found only after the treatment; however, the hTAPCs after 5-aza treatment were not able to form thick myofilaments and consequently sarcomeres. These results indicated that a terminal cardiac differentiation of hTAPCs was not achieved and that the cardiomyogenesis failure could be related to the non-muscle origin of the adipose tissue.
Author(s): Valeria Ferreira-Silva, Munira M.A. Baqui, Greice A. Molfetta, Aparecida M. Fontes, Dalila I. Zanette, Fernanda U. Ferreira, Maristela D. Orellana, Wilson A. Silva JR, Dimas T. Covas