Abstract 15049: Getting to the Heart of Transdifferentiation: Direct Conversion of Human Fibroblasts Toward Induced Cardiomyocyte-Like Cells Using Recombinant Proteins
Transformation of differentiated cells to induced pluripotent stem cells (iPSCs) has several limitations, including the low efficiency of the process and the necessity of forced expression of at least one pluripotent stem cell transcription factor. Since 2010, different strategies have been utilized in order to achieve induced-cardiomyocytes directly from fibroblasts mostly with overexpression of developmentally critical cardiac transcription factors. An alternative approach for reprogramming and direct conversion is transient activation of Oct4, Sox2, C-myc and Klf4. Since most of previous studies use retroviral transfection for transcription factor delivery, one of the major issues in application of transdifferentiation in regenerative medicine to be solved is finding a safe tool for this reprogramming process.
In the present study we treated human dermal fibroblasts and human fetal fibroblasts with a combination of 4 proteins (including Oct4, Klf4, Sox2, and c-Myc) conjugated with HIV TAT until fibroblasts enter into a partially reprogrammed state. After entering partially reprogrammed state, we directed their differentiation toward cardiac lineage with 20 ng/ml BMP4 treatment for 5 days.
Cells treated with recombinant proteins showed significantly higher expression of early-stage and late-stage cardiac markers such as GATA-4, Mef2C, NKX2.5, α-MHC, cTnT and cardiac actin, in comparison to their control. Immunofluorescence staining of transdifferentiated cells showed expressions of NKX2.5, GATA4, CARDIAC ACTIN, GJA, MLC and MHC. We called these cells “induced cardiomyocyte-like cells” (iCLCs). In vivo functionality of reprogrammed cells were tested by injection of differentiated cells to the heart of rats with myocardial infarction. 6 weeks after transplantation heart tissue were analyzed both on macroscopic and microscopic characteristics.
Conclusion: This technique offers safe and fast generation of cardiomyocytes for future applications in regenerative medicine as well as drug screening. Furthermore this novel tool might be a potential method for in vivo conversion of ischemia-triggered aggregation of fibroblasts into cardiomyocytes in infarcted heart.
- © 2013 by American Heart Association, Inc.