Hypoxic preconditioning enhances survival of human adipose-derived stem cells and conditions endothelial cells in vitro

Stem Cells Dev. 2012 Jul 20;21(11):1887-96. doi: 10.1089/scd.2011.0289. Epub 2012 Jan 27.

Abstract

To grow more robust cardiac tissue for implantation in vivo, strategies to improve survival of implanted stem cells are required. Here we report the protective effects of hypoxic preconditioning (HPC) and identify mechanisms for improving survival of adipose-derived stem cells (ASC) in vitro. Human ASC were preconditioned for 24 h with hypoxia and then exposed to simulated ischemia for a further 24 h. HPC significantly increased ASC viability, and reduced cell injury and apoptosis compared with non-preconditioned cells under ischemic conditions, as shown by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), lactate dehydrogenase-release, and caspase activity assays. Preconditioned ASC increased levels of hypoxia-inducible factor-1 alpha and secreted significantly more of the downstream target vascular endothelial growth factor (VEGF-A; 13-fold) compared with control during the 24 h. Exogenous VEGF (50 ng/mL) increased phosphorylation of Akt without affecting ERK1/2, JNK, or p38 MAPK protein levels. Phospho-Akt was also increased in preconditioned ASC compared with non-preconditioned ASC, an effect that may be mediated via VEGF-A. Importantly, the protective effects of HPC were abolished by a neutralizing antibody against VEGF-A and the phosphoinositol 3-kinase inhibitor LY294002, demonstrating the importance of VEGF-A and Akt in hypoxia-induced ASC survival. Importantly, we showed that media derived from hypoxic preconditioned ASC support endothelial cell survival and endothelial tube formation in vitro. Our in vitro findings indicate that HPC may be a promising strategy to improve survival of ASC and promote angiogenesis in ischemic environments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / cytology*
  • Cell Hypoxia
  • Cell Shape
  • Cell Survival
  • Chromones / pharmacology
  • Culture Media, Conditioned / metabolism
  • Culture Media, Conditioned / pharmacology
  • Culture Media, Serum-Free / metabolism
  • Cytoprotection
  • Endothelial Cells / drug effects*
  • Endothelial Cells / metabolism
  • Female
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Ischemia / metabolism
  • Middle Aged
  • Morpholines / pharmacology
  • Neovascularization, Physiologic
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphorylation
  • Primary Cell Culture
  • Proto-Oncogene Proteins c-akt / metabolism
  • Stem Cells / cytology*
  • Stem Cells / drug effects
  • Stem Cells / metabolism
  • Tetrazolium Salts / metabolism
  • Thiazoles / metabolism
  • Time Factors
  • Vascular Endothelial Growth Factor A / metabolism
  • Vascular Endothelial Growth Factor A / pharmacology
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Chromones
  • Culture Media, Conditioned
  • Culture Media, Serum-Free
  • HIF1A protein, human
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Morpholines
  • Phosphoinositide-3 Kinase Inhibitors
  • Tetrazolium Salts
  • Thiazoles
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Proto-Oncogene Proteins c-akt
  • p38 Mitogen-Activated Protein Kinases
  • thiazolyl blue