title: Hypoxia augments outgrowth endothelial cell (OEC) sprouting and directed migration in response to sphingosine-1-phosphate (S1P).
abstract: Therapeutic angiogenesis provides a promising approach to treat ischemic cardiovascular diseases through the delivery of proangiogenic cells and/or molecules. Outgrowth endothelial cells (OECs) are vascular progenitor cells that are especially suited for therapeutic strategies given their ease of noninvasive isolation from umbilical cord or adult peripheral blood and their potent ability to enhance tissue neovascularization. These cells are recruited to sites of vascular injury or tissue ischemia and directly incorporate within native vascular endothelium to participate in neovessel formation. A better understanding of how OEC activity may be boosted under hypoxia with external stimulation by proangiogenic molecules remains a challenge to improving their therapeutic potential. While vascular endothelial growth factor (VEGF) is widely established as a critical factor for initiating angiogenesis, sphingosine-1-phosphate (S1P), a bioactive lysophospholipid, has recently gained great enthusiasm as a potential mediator in neovascularization strategies. This study tests the hypothesis that hypoxia and the presence of VEGF impact the angiogenic response of OECs to S1P stimulation in vitro. We found that hypoxia altered the dynamically regulated S1P receptor 1 (S1PR1) expression on OECs in the presence of S1P (1.0 μM) and/or VEGF (1.3 nM). The combined stimuli of S1P and VEGF together promoted OEC angiogenic activity as assessed by proliferation, wound healing, 3D sprouting, and directed migration under both normoxia and hypoxia. Hypoxia substantially augmented the response to S1P alone, resulting in ~6.5-fold and ~25-fold increases in sprouting and directed migration, respectively. Overall, this report highlights the importance of establishing hypoxic conditions in vitro when studying ischemia-related angiogenic strategies employing vascular progenitor cells.
authors: Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America.
authors: Priscilla A
authors: PA
authors: Williams
authors: Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil.
authors: Roberta S
authors: RS
authors: Stilhano
authors: Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America.
authors: Vivian P
authors: VP
authors: To
authors: Department of Neurobiology, Physiology, and Behavior, University of California Davis, Davis, California, United States of America.
authors: Lyndon
authors: L
authors: Tran
authors: Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America.
authors: Kevin
authors: K
authors: Wong
authors: Department of Biomedical Engineering, University of California Davis, Davis, California, United States of America.
authors: Eduardo A
authors: EA
authors: Silva
mesh_terms: D000464:Alginates / Q000737:chemistry; D001681:Biological Assay; D015687:Cell Hypoxia; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D020100:Hydrogels; D008246:Lysophospholipids / Q000494:pharmacology*; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010100:Oxygen / Q000494:pharmacology*; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000081025:Sphingosine-1-Phosphate Receptors; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D014945:Wound Healing / Q000187:drug effects
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D008246:Lysophospholipids; D049349:Receptors, Lysosphingolipid; C477362:S1PR1 protein, human; D000081025:Sphingosine-1-Phosphate Receptors; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; C060506:sphingosine 1-phosphate; D020723:Glucuronic Acid; D013110:Sphingosine; D010100:Oxygen