Neuroprotection by mesenchymal stem cell (MSC) administration is enhanced by local cooling infusion (LCI) in ischemia

Objective: The present study aimed to determine if hypothermia augments the neuroprotection conferred by MSC administration by providing a conducive micro-environment. Methods: Sprague-Dawley rats were subjected to 1.5 h middle cerebral artery occlusion (MCAO) followed by 6 or 24 h of reperfusion for molecular analyses, as well as 1, 14 and 28 days for brain infarction or functional outcomes. Rats were treated with either MSC (1 x 10(5)), LCI (cold saline, 0.6 ml/min, 5 min) or both. Brain damage was determined by Infarct volume and neurological deficits. Long-term functional outcomes were evaluated using foot-fault and Rota-rod testing. Human neural SHSY5Y cells were investigated in vitro using 2 h oxygen glucose deprivation (OGD) followed by MSC with or without hypothermia (HT) (34 degrees C, 4 h). Mitochondrial transfer was assessed by confocal microscope, and cell damage was determined by cell viability, ATP, and ROS level. Protein levels of IL-1 beta, BAX, Bcl-2, VEGF and Mirol were measured by Western blot following 6 h and 24 h of reperfusion and reoxygenation. Results: MSC, LCI, and LCI + MSC significantly reduced infarct volume and deficit scores. Combination therapy of LCI + MSC precipitated better long-term functional outcomes than monotherapy. Upregulation of Mirol in the combination group increased mitochondrial transfer and lead to a greater increase in neuronal cell viability and ATP, as well as a decrease in ROS. Further, combination therapy significantly decreased expression of IL-1 beta and BAX while increasing Bcl-2 and VEGF expression. Conclusion: Therapeutic hypothermia upregulated Mirol and enhanced MSC mitochondrial transfer-mediated neuroprotection in ischemic stroke. Combination of LCI with MSC therapy may facilitate clinical translation of this approach.