Novel Strategies for Reprogramming iPS Derived Cardiac Cells

Stanford University, Stanford CA

Investigators

Abstract

DESCRIPTION (provided by applicant): Reprogramming of adult human fibroblasts into induced pluripotent stem (iPS) cells has generated significant excitement in the fields of regenerative medicine and stem cell biology. iPS cells avoid the ethical issues surrounding human embryonic stem cells (hESCs), and also have the potential for being patient- and disease-specific. However, the current method of integrating transcription factor genes into the adult cell genome requires weeks of cell culture, and so far has resulted in very low yields of iPS cells that may also become oncogenic in vivo. Inefficient delivery of transcription factors to the cells is an obstacle, but more fundamental is the failure of the introduced transcription factors to alter the pre-existing messenger RNA (mRNA) pool already within the adult cell. Thus, the adult cell's existing transcriptome continues to be translated into adult proteins while the transcription factor mRNAs slowly reaches target critical mass before overtaking the adult proteome, thus resulting in delayed pluripotency. To address these problems, we propose an innovative method for reprogramming that is based on microRNAs (miRNAs). MiRNAs are a class of small, noncoding RNA that play important posttranscriptional regulatory roles by targeting mRNA for cleavage or translational repression. The primary advantage of miRNA is that, unlike transcription factors, they will directly and immediately alter the adult transcriptome and proteome, leading to increased efficiency and decreased time for inducing pluripotency. We propose to do this by first determining the miRNA signature of adult cells after introduction of three known reprogramming factors, Oct 3/4, Sox2, and Klf4. Over-expression of this miRNA signature in adult cells using a novel non-viral delivery method should induce pluripotency.