Generation of Transgene-free Induced Pluripotent Stem Cells with Non-viral Methods

Induced pluripotent stem （iPS） cells were originally generated from mouse fibroblasts by enforced expression of Yamanaka factors （Oct3/4, Sox2, Klf4, and c-Myc）. The technique was quickly re- produced with human fibroblasts or mesenchymal stem cells. Although having been showed therapeutic po- tential in animal models of sickle ceil anemia and Parkinson＇s disease, iPS cells generated by viral methods do not suit all the clinical applications. Various non-viral methods have appeared in recent years for application of iPS cells in cell transplantation therapy. These methods mainly include DNA vector-based approaches, transfection of mRNA, and transduction of reprogramming proteins. This review summarized these non-viral methods and compare the advantages, disadvantages, efficiency, and safety of these methods.