Abstract WP141: Neuroprotection by Mesenchymal Stem Cells (MSC) Administration Was Enhanced by Local Cooling Infusion (LCI) in Ischemic Rats

Abstract

Introduction: Although mitochondrial transfer from MSCs to neurons has been found to be a promising strategy for the treatment of ischemic stroke, uncertainty regarding the appropriate quantity of MSCs and inefficient delivery to affected tissue have limited the applicability of this emerging therapy. In this study we sought, using LCI-mediated hypothermia, to provide a micro-environment conducive to mitochondrial homing and function, and thus to improve the neuroprotective efficacy of MSC mitochondrial transfer. Methods: Sprague-Dawley rats were subjected to 90min middle cerebral artery occlusion followed by 24h reperfusion. Rats were treated with either MSCs (1х10 5 ), LCI (cold saline, 0.6 ml/min, 5min) or both. After 24h reperfusion, infarct volume and neurological deficits were examined. After 28d, long-term functional outcomes were evaluated using foot-fault and rota-rod testing. In parallel, human neural SH-SY5Y cells were investigated in vitro using 2h oxygen-glucose deprivation (OGD), followed by MSC co-culture, with or without hypothermia (34°C, 4h). Mitochondrial transfer was assessed by O 2 consumption, extracellular ATP levels, mitochondrial membrane potential (MMP) in co-culture supernatant, and quantity (Western blot) of mitochondrial transfer related protein Rho GTPase Miro 1. Neural cell viability and intracellular ATP were measured at 6 h and 24 h after OGD. Results: After 24h reperfusion, MSC and LCI groups showed significant decreases in infarct volume and neuronal deficit. After 28d, the combination therapy group showed significantly greater long-term recovery than either of the monotherapy groups. With hypothermia, cell culture showed increased extracellular ATP, MMP and O 2 consumption in supernatant, cell viability, and neuronal intracellular ATP, indicating that MSC mitochondrial transfer to neurons was enhanced by hypothermia. Miro 1 was observed to be upregulated in the combination group, indicating its involvement in the transfer mechanism. Conclusion: Therapeutic hypothermia, by upregulating Miro 1 and thus improving transfer, greatly enhanced MSC mitochondrial transfer-mediated neuroprotection in ischemic stroke. This combined approach may facilitate the clinical translation of this therapy.