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BM-MSCs were exposed cell stressors mimicking the ischemic myocardium such as oxidative stress, hypoxia and inflammation. BM-MSC proliferation was documented by MTT assays whereas cell migration was determined by wound healing assay. Levels of anti-apopotic factor Bcl-xL was assessed by western blot as well as Akt activation. RESULTS: BM-MSCs were characterized by docmentation of key surface markers (CD44, CD29, CD105) and by multilineage differentiation assays. Proliferation curves were unaltered following preconditioning BM-MSCs with VEGF or AG490, in the concentration ranges studied. There was no difference in the proliferation profile when preconditioned BM-MSCs were exposed to oxidative stress, hypoxia or LPS. In vitro wound closure was improved when cells were preconditioned with 20 to 60uM of AG490. Similar findings were found for both concentrations of VEGF. The effect was even more noticeable when preconditioned MSCs were exposed to inflammatory stimuli for 24h. Bcl-xL expression levels were increased with VEGF preconditioning in hypoxic and inflammatory condition. Similarly, AG490 produced resulted in increased Bcl-XL expression although to a greater extent when preocnditionned with doses between at 20 and 40uM. Akt Phosphorylation was enhanced after exposure to hypoxia and LPS in AG490 and VEGF pre-treated cells. CONCLUSION: Our study findings indicate that AG490 and VEGF are promising preconditioning agents that can promote survival of MSCs, under stress conditions. VITAMIN C REDUCES DOXORUBICIN-INDUCED NITROSATIVE STRESS BY REGULATION OF NITRIC OXIDE SYNTHASEG Akolkar, A Bagchi, D Jassal, P Singal Winnipeg, Manitoba BACKGROUND: Despite the effectiveness of Doxorubicin (Dox) as an anti-cancer drug, the dose dependent cardiotoxic side effects are serious life threatening concerns associated with its use. In addition to the oxidative stress, there is increasing evidence of involvement of nitrosative stress in Dox-induced cardiomyopathy. Previously, Vitamin C (Vit C) has been shown to reduce oxidative stress and improved survival of Dox-treated cardiomyocytes. However, there is no information on the effect of Vit C on nitrosative stress. The objective of this study was to investigate the effect of Vit C on nitrosative stress in Dox treated cardiomyocytes. METHODS AND RESULTS: Cardiomyocytes isolated from adult Sprague-Dawley rats were treated with predetermined doses of Vit C (25 mM), Dox (10 mM) or Vit C (25 mM) + Dox (10 mM) for 24 hours. Dox induced increase in Nitric oxide synthase (NOS) activity in cardiomyocytes was blunted by Vit C treatment. Western blot analysis revealed an upregulation of inducible NOS (iNOS) leading to increased levels of nitric oxide in cardiomyocyte as well as in the medium and increased peroxynitrite formation in Dox treated cardiomyocytes. Vit C pretreatment downregulated iNOS expression and NOS activity thereby reducing cellular Nitric oxide (NO) levels and the peroxynitrite formation in Dox treated cardiomyocytes. Vit C regulated the activity of endothelial NOS (eNOS) b...

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