title: Hypoxic conditioning enhances the angiogenic paracrine activity of human adipose-derived stem cells.
abstract: Human adipose-derived stem cells (ASCs) secrete cytokines and growth factors that can be harnessed in a paracrine fashion for promotion of angiogenesis, cell survival, and activation of endogenous stem cells. We recently showed that hypoxia is a powerful stimulus for an angiogenic activity from ASCs in vitro and here we investigate the biological significance of this paracrine activity in an in vivo angiogenesis model. A single in vitro exposure of ASCs to severe hypoxia (<0.1% O2) significantly increased both the transcriptional and translational level of the vascular endothelial growth factor-A (VEGF-A) and angiogenin (ANG). The angiogenicity of the ASC-conditioned medium (ASC(CM)) was assessed by implanting ASC(CM)-treated polyvinyl alcohol sponges subcutaneously for 2 weeks in mice. The morphometric analysis of anti-CD31-immunolabeled sponge sections demonstrated an increased angiogenesis with hypoxic ASC(CM) treatment compared to normoxic control ASC(CM) treatment (percentage vascular volume; 6.0%±0.5% in the hypoxic ASC(CM) vs. 4.1%±0.7% in the normoxic ASC(CM), P<0.05). Reduction of VEGF-A and ANG levels in the ASC(CM) with respective neutralizing antibodies before sponge implantation showed a significantly diminished angiogenic response (3.5%±0.5% in anti-VEGF-A treated, 3.2%±0.7% in anti-ANG treated, and 3.5%±0.6% in anti-VEGF-A/ANG treated). Further, both the normoxic and hypoxic ASC(CM) were able to sustain in vivo lymphangiogenesis in sponges. Collectively, the model demonstrated that the increased paracrine production of the VEGF-A and ANG in hypoxic-conditioned ASCs in vitro translated to an in vivo effect with a favorable biological significance. These results further illustrate the potential for utilization of an in vitro optimized ASC(CM) for in vivo angiogenesis-related applications as an effective cell-free technology.
authors.affiliation: O'Brien Institute, Melbourne, Victoria, Australia.
authors.forename: Sarah T
authors.initials: ST
authors.lastname: Hsiao
authors.forename: Zerina
authors.initials: Z
authors.lastname: Lokmic
authors.forename: Hitesh
authors.initials: H
authors.lastname: Peshavariya
authors.forename: Keren M
authors.initials: KM
authors.lastname: Abberton
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Dusting
authors.forename: Shiang Y
authors.initials: SY
authors.lastname: Lim
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Dilley
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D015687:Cell Hypoxia / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000494:pharmacology; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010100:Oxygen / Q000494:pharmacology; D019899:Paracrine Communication / Q000187:drug effects; D012259:Ribonuclease, Pancreatic / Q000235:genetics / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics / Q000378:metabolism
chemical_list: D017077:Culture Media, Conditioned; D042461:Vascular Endothelial Growth Factor A; D042582:Vascular Endothelial Growth Factor C; C046366:angiogenin; D012259:Ribonuclease, Pancreatic; D010100:Oxygen