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Endothelial nitric oxide (eNOS)‐dependent and ‐ independent effects of hypoxia on vascular repair‐relevant functions of human CD34 + cells
Author(s) -
Joshi Shrinidh,
Jarajapu Yagna
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1201.6
Subject(s) - cd34 , enos , hypoxia (environmental) , nitric oxide , vascular endothelial growth factor , haematopoiesis , chemistry , stromal cell , stem cell , andrology , immunology , biology , microbiology and biotechnology , endocrinology , nitric oxide synthase , medicine , cancer research , vegf receptors , oxygen , organic chemistry
CD34 + hematopoietic stem cells are now known for their cardiovascular regenerative functions, and provide a breakthrough approach for the treatment of ischemic cardiovascular diseases. Vasorepairative functions of these cells are known to be potentiated by exposure to hypoxia. Previous studies have demonstrated that nitric oxide (NO) derived from eNOS plays an important role in the reparative functions of CD34 + cells. The current study evaluated the role of NO in the hypoxic potentiation of proliferation and migration, which are key functions that determine vasorepairative potential of these cells. Peripheral blood was obtained from healthy individuals (n=24) and mononuclear cells (MNCs) were separated by Ficoll centrifugation. MNCs were enriched for lineage negative cells, which were further enriched for CD34 + cells by immunomagnetic selection. Hypoxic exposure to hypoxia (1% oxygen) was accomplished by using a hypoxia chamber (Biospherix, Inc.). Intracellular NO levels were detected by DAF‐FM flow cytometry with and without the following treatments: N ω ‐nitro‐l‐arginine‐methyl ester (L‐NAME), stromal derived factor‐1a (SDF) or vascular endothelial growth factor (VEGF). Effects of SDF or VEGF on proliferation and migration of CD34 + cells were evaluated under normoxic or hypoxic conditions. Hypoxic exposure increased intracellular NO levels (P<0.01, n=8) that were not affected by L‐NAME (300 μM) pretreatment (n=8). Basal proliferation and migration were enhanced (P<0.05, n=6) by hypoxic exposure that were resistant to L‐NAME (n=6). Proliferation and migration to either SDF or VEGF were potentiated by hypoxia (P<0.05, n=6), which was partly antagonized by L‐NAME (n=6). These findings suggest that hypoxia induces NO generation independent of eNOS, which potentiates proliferation and migration in CD34 + cells. Stimulatory effects of SDF or VEGF are at least in part mediated by eNOS activation in normoxic and hypoxic conditions. Support or Funding Information This work is partly supported by American Heart Association, and the Core Biology Facility at North Dakota State University, that was made possible by NIGMS (P30 GM103332‐01).