Abstract 15412: Non-viral Direct Reprogramming of Fibroblasts Into a Three Dimensional Vascularized Cardiomimetic Tissue
Background and Hypothesis: Transcription factors or microRNAs were demonstrated to directly reprogram fibroblasts into cardiomyocytes (CMs), endothelial cells (ECs), or smooth muscle cells (SMCs). However, simultaneous reprogramming into CMs and vascular cells has not been reported. Several muscle-specific miRNAs are involved in cardiac development and differentiation. Accordingly, we hypothesized that these muscle-specific miRNAs could reprogram fibroblasts into various cardiac cell types.
Methods and Results: We transfected miRNA mimics miR-1a-2-5p, miR-208a-3p, miR-208b-3p, miR-208b-5p or miR-499-5p separately or in combinations, into adult mouse tail-tip fibroblasts w/wo ascorbic acid (AA) and BMP4. qRT-PCR analyses showed that miR-208b-3p most highly induced mRNA expression of CM-, EC-, SMC-marker genes. A combined treatment of AA and BMP4 enhanced reprogramming efficiency and maturation, as evidenced by spontaneous contractions of reprogrammed CM (rCMs) and formation of vascular network by reprogrammed ECs (rECs) and reprogrammed SMCs (rSMCs). The rECs accounted for 37 ± 6 % of the total cells. Ten days after the treatment, a substantial amount of extracellular matrix was deposited, leading to formation of a tissue-like patch referred to as cardiomimetic tissue (CMT). We transplanted CMT labeled with CM-Dil or generated from fibroblasts of GFP transgenic mice onto the apex of the mouse heart. At week 4, histologic examination of the heart sections showed robust engraftment and retention of CMT-derived cells. Systemic perfusion of BLS-1 lectin at week 4 revealed formation of functional blood vessels by rECs alone or together with host ECs. In addition, rCMs formed mass-like structures, consisting of 11.9 ± 4.4 % cells in the transplanted CMT, and showed clear striations and GJA1 (Connexin 43) expression between cardiomyocytes.
In conclusion, we for the first time demonstrated that a combined treatment of a specific miRNA mimic, AA, and BMP4 is able to reprogram postnatal fibroblasts into functional CM-, EC- and SMCs-like cells, induce formation of ECMs, and generate a cardiac-tissue like structure. This novel tissue reprogramming can serve as a platform for cell therapy, disease modeling and drug development.
Author Disclosures: J. Cho: None. S. Kim: None. H. Park: None. M. Song: None. S. Lee: None. J. Jung: None. S. Yu: None. M.A. Sussman: None. R.P. Harvey: None. Y. Yoon: None.
- © 2014 by American Heart Association, Inc.