Improved survival of mesenchymal stromal cell after hypoxia preconditioning: Role of oxidative stress

Aims: To investigate the mechanisms underlying the beneficial effect of hypoxia preconditioning (HPC) on mesenchymal stromal cells (MSCs) and optimize novel non-invasive methods to assess the effect of biological interventions aimed to increased cell survival. Main methods: MSCs from rat femur, with or without HPC, were exposed to hypoxic conditions in cell culture (1% O-2 for 24 h) and cell survival (by the LDH release assay and Annexin-V staining) was measured. Oxidant status (conversion of dichloro-fluorescein-DCF- and dihydro-ethidium-DHE-, protein expression of oxidant enzymes) was characterized, together with the mobility pattern of cells under stress. Furthermore, cell survival was assessed non-invasively using state-of-the-art molecular imaging. Key findings: Compared to controls, Hypoxia resulted in increased expression of the oxidative stress enzyme NAD(P)H oxidase (subunit 67(Phox): 0.05 +/- 0.01 AU and 0.48 +/- 0.02 AU, respectively, p<0.05) and in the amount of ROS (DCF: 13 +/- 1 and 42 +/- 3 RFU/mu g protein, respectively, p<0.05) which led to a decrease in stem cell viability. Hypoxia preconditioning preserved cell biology, as evidenced by preservation of oxidant status (16 +/- 1 RFU/mu g protein, p<0.05 vs. hypoxia), and cell viability. Most importantly, the beneficial effect of HPC can be assessed non-invasively using molecular imaging. Significance: HPC preserves cell viability and function, in part through preservation of oxidant status, and its effects can be assessed using state-of-the-art molecular imaging. Understanding of the mechanisms underlying the fate of stem cells will be critical for the advancement of the field of stem cell therapy. (C) 2010 Elsevier Inc. All rights reserved.