• Oxidative stress-induced autophagy compromises stem cell viability.

      Prakash, Ravi; Fauzia, Eram; Siddiqui, Abu Junaid; Yadav, Santosh Kumar; Kumari, Neha; Shams, Mohammad Tayyab; Naeem, Abdul; Praharaj, Prakash P; Khan, Mohsin Ali; Bhutia, Sujit Kumar; et al. (Oxford University Press, 2022-03-16)
      Stem cell therapies have emerged as a promising treatment strategy for various diseases characterized by ischemic injury such as ischemic stroke. Cell survival after transplantation remains a critical issue. We investigated the impact of oxidative stress, being typically present in ischemically challenged tissue, on human dental pulp (hDPSC) and mesenchymal stem cell (hMSC). We used oxygen-glucose deprivation (OGD) to induce oxidative stress in hDPSC and hMSC. OGD-induced generation of O2 •- or H2O2 enhanced autophagy by inducing the expression of Activating Molecule in BECN1-Regulated Autophagy Protein 1 (Ambra1) and Beclin1 in both cell types. However, hDPSC and hMSC pre-conditioning using reactive oxygen species (ROS) scavengers significantly repressed the expression of Ambra1 and Beclin1 and inactivated autophagy. O2 •- or H2O2 acted upstream of autophagy, and the mechanism was unidirectional. Further, our findings revealed ROS-p38-Erk1/2 involvement. Pre-treatment with selective inhibitors of p38 and Erk1/2 pathways (SB202190 and PD98059) reversed OGD effects on the expression of Ambra1 and Beclin1, suggesting that these pathways induced oxidative stress-mediated autophagy. SIRT3 depletion was found to be associated with increased oxidative stress and activation of p38 and Erk1/2 MAPKs pathways. Global ROS inhibition by NAC or a combination of polyethylene glycol-superoxide dismutase (PEG-SOD) and polyethylene glycol-catalase (PEG-catalase) further confirmed that O2 •- or H2O2 or a combination of both impacts stems cell viability by inducing autophagy. Further, autophagy inhibition by 3-Methyladenine (3-MA) significantly improved hDPSC viability. These findings contribute to a better understanding of post-transplantation hDPSC and hMSC death and may inform strategies to minimize therapeutic cell loss under oxidative stress.