Preconditioning mesenchymal stem cells with caspase inhibition and hyperoxia prior to hypoxia exposure increases cell proliferation

Abstract

Myocardial infarction is a leading cause of mortality and morbidity worldwide. Occlusion of a coronary artery produces ischemia and myocardial necrosis that leads to left ventricular (LV) remodeling, dysfunction, and heart failure. Stem cell therapy may decrease infarct size and improve LV function; the hypoxic environment, however, following a myocardial infarction may result in apoptosis, which in turn decreases survival of transplanted stem cells. Therefore, the effects of preconditioned mesenchymal stem cells (MSC) with hyperoxia (100% oxygen), Z-VAD-FMK pan-caspase inhibitor (CI), or both in a hypoxic environment in order to mimic conditions seen in cardiac tissue post-myocardial infarction were studied in vitro. MSCs preconditioned with hyperoxia or CI significantly decreased apoptosis as suggested by TUNEL assay and Annexin V analysis using fluorescence assisted cell sorting. These effects were more profound when both, hyperoxia and CI, were used. Additionally, gene and protein expression of caspases 1, 3, 6, 7, and 9 were down-regulated significantly in MSCs preconditioned with hyperoxia, CI, or both, while the survival markers Akt1, NF-κB, and Bcl-2 were significantly increased in preconditioned MSCs. These changes ultimately resulted in a significant increase in MSC proliferation in hypoxic environment as determined by BrdU assays compared to MSCs without preconditioning. These effects may prove to be of great clinical significance when transplanting stem cells into the hypoxic myocardium of post-myocardial infarction patients in order to attenuate LV remodeling and improve LV function.

Regulation of the mitochondrial reactive oxygen species: Strategies to control mesenchymal stem cell fates ex vivo and in vivo

“…On the other hand, Karlsen et al showed that hyperoxia of room air was not adverse for the proliferation, differentiation, or phenotype of bone marrow derived MSCs in vitro. Saini et al demonstrated that preconditioned with hyperoxia decreased the apoptosis of MSCs, while increased the the level of survival markers including Akt1, NF‐κB, and Bcl‐2. However, whether hyperoxia will alter the MSC activities via ROS related pathway need to to be further investigated.…”

Activity of mesenchymal stem cells in therapies for chronic skin wound healing

“…Saini et al showed hyperoxic and pancaspase pre-treatment of the cells substantially decreased MSC apoptosis in a cardiac infarct model, a scenario that produces an ischemic environment for implanted MSCs. 103 Conversely, Chang et al recently demonstrated the advantages of preconditioning MSCs in hypoxia, which was shown to improve the secretory capabilities of the cells (VEGF, HGF, and others), a main benefit of MSC therapy. 104 Gene therapy in MSCs has also received some attention, as Wang et al recently showed that adenoviral upregulation of protein kinase G1α improved MSC survival following implantation into a similar cardiac infarct model.…”

Hypoxia and hyperoxia differentially control proliferation of rat neural crest stem cells via distinct regulatory pathways of the HIF1α–CXCR4 and TP53–TPM1 proteins

“…), indicating that the inhibitory effect of hyperoxia on cell viability and proliferation is also cell type‐specific. In fact, previous studies have shown that hypoxia exposure decreases proliferation and viability of both human and rat MSCs (Holzwarth et al, ; Saini et al, ), and hyperoxia (100% O 2 ) preconditioning before hypoxia exposure significantly increases the proliferation and survival rates of the rMSCs (Saini et al, ).…”