Reprogramming of human fibroblasts toward a cardiac fate

Abstract

Reprogramming of mouse fibroblasts toward a myocardial cell fate by forced expression of cardiac transcription factors or microRNAs has recently been demonstrated. The potential clinical applicability of these findings is based on the minimal regenerative potential of the adult human heart and the limited availability of human heart tissue. An initial but mandatory step toward clinical application of this approach is to establish conditions for conversion of adult human fibroblasts to a cardiac phenotype. Toward this goal, we sought to determine the optimal combination of factors necessary and sufficient for direct myocardial reprogramming of human fibroblasts. Here we show that four human cardiac transcription factors, including GATA binding protein 4, Hand2, T-box5, and myocardin, and two microRNAs, miR-1 and miR-133, activated cardiac marker expression in neonatal and adult human fibroblasts. After maintenance in culture for 4-11 wk, human fibroblasts reprogrammed with these proteins and microRNAs displayed sarcomere-like structures and calcium transients, and a small subset of such cells exhibited spontaneous contractility. These phenotypic changes were accompanied by expression of a broad range of cardiac genes and suppression of nonmyocyte genes. These findings indicate that human fibroblasts can be reprogrammed to cardiac-like myocytes by forced expression of cardiac transcription factors with muscle-specific microRNAs and represent a step toward possible therapeutic application of this reprogramming approach.cardiogenesis | cell fate specification | phenotypic switching | regeneration

Resetting the epigenome for heart regeneration.

“…Previous studies showed that members of the core cardiogenic gene program Gata4, Mef2c, Tbx5 (and Hand2) (GMT or GMTH) reprogrammed cardiac fibroblasts into spontaneously contracting cardiac-like myocytes in vitro [109] and in vivo [129]. Recapitulation of these studies in human fibroblasts showed that GATA4, TBX5, HAND2 and two MEF2C-regulated miRNAs, miR-133 and miR-1, upregulated the expression of cardiac troponin T and tropomyosin (markers of cardiomyocytes) and created a small subset of spontaneously beating cardiomyocytes [130]. Cumulatively, these studies suggest fibroblasts, or indeed other cells types within and surrounding the infarct, could represent a viable target for cardiomyogenesis.…”

“…Cumulatively, these studies suggest fibroblasts, or indeed other cells types within and surrounding the infarct, could represent a viable target for cardiomyogenesis. However, reprogramming of cell identity, in both pluripotency and direct reprogramming approaches, is an inefficient process and current strategies result in off-target effects in other cell types within and outside the heart [109,124,[130][131][132]. Few studies have interrogated epigenomic profiles after fibroblast direct reprogramming to cardiomyocytes but epigenomic reconfiguration of histone marks (H3K4me3 and H3K27me3) and DNA methylation patterns at sarcomeric gene loci has been validated in mouse [109,133,134] and human induced cardiomyocytes [109,[133][134][135].…”

Proceedings of the Uehara Memorial Foundation. Innovative Medicine: Basic Research and Development. Cardiac Reprogramming for Heart Repair

“…Nam et al reported that a combination of Gata4, Hand2, Tbx5, Myocd, miR-1, and miR-133 induced 13 % of adult HCFs to express cardiac troponin T protein and that a small subset of the iCMs exhibited spontaneous contractility after 11 weeks in culture [ 15 ]. Islas et al reported that transient overexpression of Ets2 and Mesp1 could reprogram human dermal fi broblasts into cardiac progenitor-like cells [ 16 ].…”

We heart cultured hearts. A comparative review of methodologies for targeted differentiation and maintenance of cardiomyocytes derived from pluripotent and multipotent stem cells

“…Delivery of cardio-specific transcription factors and/or or microRNAs to infarcted mouse hearts had also been shown to result in direct transdifferentiation of fibroblasts into cardiomyocyte-like cells in vivo and improvement of the functioning of the damaged myocardium [82,84,85]. Human fibroblasts have also been induced to transdifferentiate into cardiomyocyte-like cells in vitro using basically the same cardio-specific transcription factors (GATA4, HAND2, TBX5 and MEF2C) [82] or transcription factors (GATA4, HAND2, TBX5, and myocardin) plus microRNAs (miR-1 and miR-133) [86].…”