title: Conversion of human fibroblasts to functional endothelial cells by defined factors.
abstract: OBJECTIVE
  Transdifferentiation of fibroblasts to endothelial cells (ECs) may provide a novel therapeutic avenue for diseases, including ischemia and fibrosis. Here, we demonstrate that human fibroblasts can be transdifferentiated into functional ECs by using only 2 factors, Oct4 and Klf4, under inductive signaling conditions.
  
  
  RESULTS
  To determine whether human fibroblasts could be converted into ECs by transient expression of pluripotency factors, human neonatal fibroblasts were transduced with lentiviruses encoding Oct4 and Klf4 in the presence of soluble factors that promote the induction of an endothelial program. After 28 days, clusters of induced endothelial (iEnd) cells seemed and were isolated for further propagation and subsequent characterization. The iEnd cells resembled primary human ECs in their transcriptional signature by expressing endothelial phenotypic markers, such as CD31, vascular endothelial-cadherin, and von Willebrand Factor. Furthermore, the iEnd cells could incorporate acetylated low-density lipoprotein and form vascular structures in vitro and in vivo. When injected into the ischemic limb of mice, the iEnd cells engrafted, increased capillary density, and enhanced tissue perfusion. During the transdifferentiation process, the endogenous pluripotency network was not activated, suggesting that this process bypassed a pluripotent intermediate step.
  
  
  CONCLUSIONS
  Pluripotent factor-induced transdifferentiation can be successfully applied for generating functional autologous ECs for therapeutic applications.
authors.affiliation: Gladstone Institute of Cardiovascular Disease, University of California, San Francisco, CA 94158, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Ngan F
authors.initials: NF
authors.lastname: Huang
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Laurent
authors.forename: Jerry C
authors.initials: JC
authors.lastname: Lee
authors.forename: Janet
authors.initials: J
authors.lastname: Okogbaa
authors.forename: John P
authors.initials: JP
authors.lastname: Cooke
authors.forename: Sheng
authors.initials: S
authors.lastname: Ding
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D015820:Cadherins / Q000378:metabolism*; D054338:Cell Transdifferentiation / Q000502:physiology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000166:cytology* / Q000637:transplantation; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology; D006801:Humans; D007511:Ischemia / Q000628:therapy; D000090062:Kruppel-Like Factor 4; D051379:Mice; D018919:Neovascularization, Physiologic / Q000502:physiology*; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D058729:Peripheral Arterial Disease / Q000628:therapy; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014841:von Willebrand Factor / Q000378:metabolism; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D000090062:Kruppel-Like Factor 4; D050814:Octamer Transcription Factor-3; D014841:von Willebrand Factor; D000099152:Cadherin 5; C000715467:KLF4 protein, human; C000715468:Klf4 protein, mouse
keywords: angiogenesis; direct reprogramming; endothelium; peripheral vascular disease; stem cells; transdifferentiation