Nazish Sayed1, Wing Tak Wong1, Frank Ospino1, Shu Meng1, Jieun Lee1, Arshi Jha1, Phillip Dexheimer1, Bruce J Aronow1, John P Cooke2. 1. From the Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX (N.S., W.T.W., F.O., S.M., J.P.C.); Division of Cardiovascular Medicine, Stanford University, Stanford, CA (J.L., A.J.); and Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.D., B.J.A.). 2. From the Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX (N.S., W.T.W., F.O., S.M., J.P.C.); Division of Cardiovascular Medicine, Stanford University, Stanford, CA (J.L., A.J.); and Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH (P.D., B.J.A.). jpcooke@houstonmethodist.org.
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 with the use of viral vectors encoding transcription factors. We recently discovered that the viral vectors are more than passive vehicles for transcription factors because they participate actively in the process of nuclear reprogramming to pluripotency by increasing epigenetic plasticity. On the basis of this recognition, we hypothesized that small-molecule activators of toll-like receptor 3, together with external microenvironmental cues that drive endothelial cell (EC) specification, might be sufficient to induce transdifferentiation of fibroblasts into ECs (induced ECs). METHODS AND RESULTS: We show that toll-like receptor 3 agonist Poly I:C, combined with exogenous EC growth factors, transdifferentiated human fibroblasts into ECs. These induced ECs were comparable to human dermal microvascular ECs in immunohistochemical, genetic, and functional assays, including the ability to form capillary-like structures and to incorporate acetylated low-density lipoprotein. Furthermore, induced ECs significantly improved limb perfusion and neovascularization in the murine ischemic hindlimb. Finally, using genetic knockdown studies, we found that the effective transdifferentiation of human fibroblasts to ECs requires innate immune activation. CONCLUSIONS: This study suggests that manipulation of innate immune signaling may be generally used to modify cell fate. Because 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.
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 with the use of viral vectors encoding transcription factors. We recently discovered that the viral vectors are more than passive vehicles for transcription factors because they participate actively in the process of nuclear reprogramming to pluripotency by increasing epigenetic plasticity. On the basis of this recognition, we hypothesized that small-molecule activators of toll-like receptor 3, together with external microenvironmental cues that drive endothelial cell (EC) specification, might be sufficient to induce transdifferentiation of fibroblasts into ECs (induced ECs). METHODS AND RESULTS: We show that toll-like receptor 3 agonist Poly I:C, combined with exogenous EC growth factors, transdifferentiated human fibroblasts into ECs. These induced ECs were comparable to human dermal microvascular ECs in immunohistochemical, genetic, and functional assays, including the ability to form capillary-like structures and to incorporate acetylated low-density lipoprotein. Furthermore, induced ECs significantly improved limb perfusion and neovascularization in the murineischemic hindlimb. Finally, using genetic knockdown studies, we found that the effective transdifferentiation of human fibroblasts to ECs requires innate immune activation. CONCLUSIONS: This study suggests that manipulation of innate immune signaling may be generally used to modify cell fate. Because 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.
Authors: Ngan F Huang; Hiroshi Niiyama; Christoph Peter; Abhijit De; Yasodha Natkunam; Felix Fleissner; Zongjin Li; Mark D Rollins; Joseph C Wu; Sanjiv S Gambhir; John P Cooke Journal: Arterioscler Thromb Vasc Biol Date: 2010-02-18 Impact factor: 8.311
Authors: Cole Trapnell; Brian A Williams; Geo Pertea; Ali Mortazavi; Gordon Kwan; Marijke J van Baren; Steven L Salzberg; Barbara J Wold; Lior Pachter Journal: Nat Biotechnol Date: 2010-05-02 Impact factor: 54.908