Abstract
Cellular plasticity progressively declines with development and differentiation, yet these processes can be experimentally reversed by reprogramming somatic cells to induced pluripotent stem cells (iPSCs) using defined transcription factors. Advances in reprogramming technology over the past 15 years have enabled researchers to study diseases with patient-specific iPSCs, gain fundamental insights into how cell identity is maintained, recapitulate early stages of embryogenesis using various embryo models, and reverse aspects of aging in cultured cells and animals. Here, we review and compare currently available reprogramming approaches, including transcription factor-based methods and small molecule-based approaches, to derive pluripotent cells characteristic of early embryos. Additionally, we discuss our current understanding of mechanisms that resist reprogramming and their role in cell identity maintenance. Finally, we review recent efforts to rejuvenate cells and tissues with reprogramming factors, as well as the application of iPSCs in deriving novel embryo models to study pre-implantation development.