Abstract 9398: Upregulation of iNOS in Mesenchymal Stem Cells Mediates Cardioprotection against Hypoxia via Activating HIF-1α
Nitric oxide (NO), a highly reactive free radical, plays an important role in the regulation of vascular and immune function, antiapoptosis, and neurotransmission. Nitric oxide synthase (NOS) catalyses NO synthesis from l-arginine. In this study, we hypothesized that mesenchymal stem cell (MSC) protected cardiomyocytes against ischemic injury via activating inducible NOS (iNOS).
Methods: MSCs were obtained from transgenic mice overexpressing green fluorescent protein (GFP). The expression of iNOS in MSCs was analyzed by quantitative real time PCR and Western blot. To investigate the cardioprotection, MSCs were separately co-cultured with cardiomyocytes (CM) in a dual-chamber culture system. Primary cultured CM were obtained from neonatal rat ventricles. Hypoxic treatment was used to mimic ischemic injury. CM damage was assessed by annexin-V staining, DNA fragmentation, and LDH release.
Results: The activity of iNOS in MSCs was significantly increased following exposure to hypoxia (Fig. A, B), which was blocked by 2-methoxyestradiol (2-ME2), a HIF-1α inhibitor (5μmol) and HIF-1α neutralizing antibody (Fig. C). MSC showed a significant increased survival of CM in a hypoxic environment, which was abolished by the selective iNOS inhibitor, 1400W (10 mg/L) and a potent competitive inhibitor of NOS, L-NAME (200 μmol/L) (Fig. D ∼ F), as well as by neutralizing HIF-1α and iNOS antibodies.
Conclusion: MSC protect cardiomyocytes against hypoxic injury partially by up-regulating iNOS via activating HIF-1α.
- © 2010 by American Heart Association, Inc.