Improved survival of mesenchymal stromal cell after hypoxia preconditioning: role of oxidative stress.
OBJECTIVE
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.


METHODS
MSCs from rat femur, with or without HPC, were exposed to hypoxic conditions in cell culture (1% O(2) for 24h) 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.


RESULTS
Compared to controls, Hypoxia resulted in increased expression of the oxidative stress enzyme NAD(P)H oxidase (subunit 67(phox): 0.05 ± 0.01AU and 0.48 ± 0.02AU, respectively, p<0.05) and in the amount of ROS (DCF: 13 ±1 and 42 ± 3 RFU/μg 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/μg protein, p<0.05 vs. hypoxia), and cell viability. Most importantly, the beneficial effect of HPC can be assessed non-invasively using molecular imaging.


CONCLUSIONS
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.
Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, MN, USA.
Karen M
KM
Peterson
Abdelrahman
A
Aly
Amir
A
Lerman
Lilach O
LO
Lerman
Martin
M
Rodriguez-Porcel
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015153:Blotting, Western; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology; D019194:Ischemic Preconditioning; D059630:Mesenchymal Stem Cells / Q000378:metabolism / Q000502:physiology*; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley