Ali Reza akhzari - Student Research Committee, Qom University of Medical Science, Qom, Iran
Fatemeh Heidari - Assistant Prof, Department of Anatomical Sciences, Qom University of Medical Science, Qom, Iran
Zeinab Hamidi zad - Student Research Committee, Qom University of Medical Science, Qom, Iran

Background and Objective: Nowadays, cell transplantation has drawn tremendous interest as a novel approach to improve the various diseases. Different cell populations, such as embryonic stem cells, cord blood cells, and mesenchymal stem cells, have been suggested as a source for replacement therapy in various diseases. With regards to the limitations of using different stem cells, transdifferentiation of the full differentiated cells can be the other choice. In this study, we showed that heart extract could induce transdifferentiation of mouse embryonic fibroblasts (MEFs) into cardiomyocytes. Material & methods: MEFs were used as a primary source of cells. Cardiomyocyte extract was prepared from adult mouse cardiomyocytes. Cytotoxicity assay for extract was performed. MEFs were treated with 5-deoxy Azacytidin and Trichostatin A. Then, the treated cells were permeabilized with streptolysin O, exposed to the mouse cardiomyocyte extract for an hour and resealed by CaCl2. The cells were cultured for 24 hours,10 and 21 days. Immunocytochemistry was performed for detecting cardiomyocyte markers; and the expression of myosin heavy chain, cardiac troponin T, atrial natriuretic peptid and α actinin antibodies was assesed. Findings: Cytotoxicity assay revealed that the extract was not toxic to the fibroblast cells. After exposure to cardiomyocytes extract, in some of the permeabilized and cardiac extract treated cells the morphology was changed significantly and some cells showed multiple nuclei after 21 days. Immunocytochemistry revealed that some cells expressed myosin heavy chain, atrial natriuretic peptid, alpha actinin and cardiac troponin T after 21 days. Mouse embryonic fibroblasts expressed 4 cardiac markers in the trichostatine and azacytidine exposed cells which were permeablized in the presence of the cardiomyocytes extract. The pre-expressed cells to Trichostatin A and 5- Azacytidin could also express α actinin and myosin heavy chain in the absence of extract. Conclusion, the fibroblasts expressed cardiomyocyte markers and showed significant morphological modification. This may be due to treatment with 5-deoxy Azacytidine and trichostatin A and exposure to the cardiomyocyte extract. It seems that the cardiomyocyte extract can induce tarnsdifferentiation of mouse embryonic fibroblasts into cardiomyocyte. This study shows that mouse embryonic fibroblasts have the capability to use as a source of cells for reprogramming procedures in the future research.

Fibroblasts, Extract, Transdifferentiation, Cardiomyocyte