title: Angiogenesis potential of human limbal stromal niche cells.
abstract: OBJECTIVE
  The perivascular localization of stem cell (SC) niches suggests the presence of a vascular niche. We aimed to determine the angiogenesis potential of limbal niche cells (NCs).
  
  
  METHODS
  Human limbal NCs were isolated and serially passaged on plastic or coated Matrigel in embryonic SC medium containing BFGF and leukemia inhibitory factor before being reseeded in 3D Matrigel. Expression of angiogenesis markers was assessed by RT-qPCR and immunofluorescence staining. Their angiogenesis potential was measured by differentiation into vascular endothelial cells and by supporting vascular tube network formed by human umbilical vein endothelial cells (HUVEC) on Matrigel. Their support of limbal epithelial progenitor cells (LEPC) was examined in sphere growth formed by reunion in 3D Matrigel.
  
  
  RESULTS
  On plastic, limbal NC could be cultured only up to four passages before turning into myofibroblasts. In contrast, on coated Matrigel, they could be expanded for up to 12 passages with upregulation of markers suggestive of angiogenesis progenitors when reseeded in 3D Matrigel because they could differentiate into vascular endothelial cells and pericytes stabilizing the tube network formed by HUVEC. Although both expanded limbal NCs and HUVEC rejoined with LEPC to form spheres to upregulate expression of ΔNp63α, CK15, and CEBPδ, the former but not the latter abolished expression of CK12 keratin.
  
  
  CONCLUSIONS
  Human limbal NCs continuously expanded on the basement membrane differentiate into angiogenesis progenitors that prevent differentiation of LEPC/SCs. They may partake in formation of the vascular niche and contribute to angiogenesis during wound healing.
authors.affiliation: Department of Ophthalmology, Tongji Hospital, Wuhan, People's Republic of China.
authors.forename: Gui-Gang
authors.initials: GG
authors.lastname: Li
authors.forename: Szu-Yu
authors.initials: SY
authors.lastname: Chen
authors.forename: Hua-Tao
authors.initials: HT
authors.lastname: Xie
authors.forename: Ying-Ting
authors.initials: YT
authors.lastname: Zhu
authors.forename: Scheffer C G
authors.initials: SC
authors.lastname: Tseng
mesh_terms: D000328:Adult; D000368:Aged; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis / Q000235:genetics*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D053569:Keratin-15 / Q000235:genetics; D016850:Limbus Corneae / Q000166:cytology* / Q000378:metabolism; D008875:Middle Aged; D018919:Neovascularization, Physiologic / Q000502:physiology*; D012313:RNA / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055153:Stem Cell Niche / Q000235:genetics*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis / Q000235:genetics*; D055815:Young Adult
chemical_list: D051017:Apoptosis Regulatory Proteins; D022782:CCAAT-Enhancer-Binding Protein-beta; C545012:CEBPB protein, human; D053569:Keratin-15; C115051:TP63 protein, human; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D012313:RNA