Transdifferentiation of Human Fibroblasts to Endothelial Cells

Abstract

Background Cell fate is fluid, and may be altered experimentally by the forced expression of master regulators mediating cell lineage. Such reprogramming has been achieved using viral vectors encoding transcription factors. We recently discovered that the viral vectors are more than passive vehicles for transcription factors, as they participate actively in the process of nuclear reprogramming to pluripotency by increasing epigenetic plasticity. Based on this recognition, we hypothesized that small molecule activators of toll-like receptor 3 (TLR3), together with external microenvironmental cues that drive EC specification, might be sufficient to induce transdifferentiation of fibroblasts into ECs (iECs). Methods and Results We show that TLR3 agonist Poly I:C, combined with exogenous EC growth factors, transdifferentiated human fibroblasts into ECs. These iECs were comparable to HMVEC in immunohistochemical, genetic and functional assays, including the ability to form capillary-like structures and to incorporate acetylated-LDL. Furthermore, iECs significantly improved limb perfusion and neovascularization in the murine ischemic hindlimb. Finally, using genetic knockdown studies, we find that the effective transdifferentiation of human fibroblasts to endothelial cells requires innate immune activation. Conclusions This study suggests that manipulation of innate immune signaling may be generally used to modify cell fate. As similar signaling pathways are activated by damage associated molecular patterns, epigenetic plasticity induced by innate immunity may play a fundamental role in transdifferentiation during wound healing and regeneration. Finally, this study is a first step toward development of a small molecule strategy for therapeutic transdifferentiation for vascular disease.

Marked Vascular Dysfunction in a Case of Peripartum Cardiomyopathy

“…3a) and then subjected them to functional assays to assess their endothelial phenotype. Specifically, we tested the inherent ability of ECs to form three-dimensional vascular networks or uptake acetylated low-density lipoprotein (Ac-LDL) [6]. Consistent with our wire myography data, primary ECs isolated from the PPCM patient’s LADs showed a decreased capacity to form networks of tubular structures when placed on ma­trigel compared to primary ECs isolated from healthy controls (Fig.…”

Vascular Regeneration by Stem/Progenitor Cells

“…These induced endothelial cells were also verified by a series of functional assays both in vivo and in vitro. 82 …”

Meeting Report for NIH 2016 Progenitor Cell Biology Consortium Cardiovascular Tissue Engineering 2016

“…Similarly, his group has shown that the transdifferentiation of fibroblasts to endothelial cells requires activation of innate immune pathways. 2 More recently, his group has preliminary data that innate immune activation of inducible NO synthase results in nitrosylation of epigenetic modifiers that causes a release of suppressive epigenetic mechanisms. Dr Daniel J. Garry (University of Minnesota) presented his recent works on cardiac progenitors that reside in the adult heart and emphasized that the role cardiac progenitor cells during aging and after injury remains unclear but represents an area of active investigation.…”