Moderate Hypothermia Promotes BMSCs Survivability In Hypoxic Environment By Increasing Multi-proteins SUMO Ylation

Objective: Acute cerebral infarction can progress rapidly,and there are limited specific and effective treatments.Small ubiquitin-like modifier(SUMO)are an important post-translational modification of proteins.Following cerebral infarction,multiple proteins can combine with SUMO to protect nerve cells,moreover,moderate hypothermia(33–34°C)can increase the level of multi-protein sumoylation.In the present study,we tried to see if moderate hypothermia can increase the survival rate of bone marrow stromal stem cells(BMSCs)planted in the cerebral ischemic penumbra by adding multiple proteins sumoylation.Firstly,BMSCs were exposed to oxygen glucose deprivation(OGD)under moderate hypothermic(33°C)conditions,and then adult rats with middle cerebral artery occlusion were treated with a combination of BMSCs and moderate hypothermia(32-34°C).Results showed that hypothermia promoted the combination of multi-proteins with SUMO in BMSCs,and induced transport of SUMO from the cytoplasm to the nucleus.Moderate hypothermia also reduced BMSCs damage following OGD,and improved BMSC survival after transplanted into the penumbra.These data suggested that moderate hypothermia may protect against BMSC injury via rapid SUMOylation of intracellular proteins.Thus,BMSC transplantation combined with moderate hypothermia may be a potential therapeutic strategy to treat cerebral infarction.Methods: BMSCs were isolated and identified by Flow Cytometry.The differentiation of BMSCs was induced by different culture conditions.BMSCs were identified by Flow Cytometry and easur fluorescent staining.BMSCs were treated with moderate hypothermia,the expression level of SUMO was determined by Western Blot.The expression of UBC9 in BMSCs was knocked down by RNA interference.BMSCs were treated with OGD and the expression of SUMO was detected by Western Blot.The apoptosis of BMSCs was detected by Western Blot.And LDH secretion levels were easured.BMSCs transplantation was performed at 37 ℃ in the ischemic penumbra of the rats.The rats were treated with mild hypothermia combined with BMSCs transplantation and mild hypothermia combined with SiUBC9 BMSCs stem cell transplantation.The neurological function scores of the rats were measured after the MCAO model was made.Results: BMSCs expressed partially neuron-specific protein NSE and glial cell marker protein GFAP in glial cells conditioned medium.The combination of SUMO1 and SUMO2/3 with the target protein in the BMSCs induced the nuclear translocation of SUMO;SiUBC9 inhibited SUMO1 and SUMO2/3 binding to the target protein in the hypoxic state of cells;Can reduce the apoptosis rate and LDH secretion of BMSCs under hypoxia condition,which is SUMOs-dependent.Mild hypothermia could increase the survival rate of BMSCs transplanted into the ischemic penumbra,and the transplantation of mild hypothermia combined with BMSCs could improve the cerebral function of rats after cerebral infarction.Conclusion:1.BMSCs can express partially neuron-specific protein NSE,and most of them express glial cell marker protein GFAP in glial cell conditioned medium.2.SUMO1,SUMO2/3 binds to the target protein in the BMSCs,and induces SUMO nuclear translocation.SiUBC9 inhibits SUMO1 and SUMO2/3 binding to the target protein in hypoxic condition.Mild hypothermia can reduce BMSCs Oxygen status of the apoptosis ratio and LDH secretion,SUMO-dependent.3.Moderate hypothermia can increase the survival rate of BMSCs transplanted into rat ischemic penumbra,and it is SUMOs-dependent.4.The protective effect of moderate temperature on BMSCs in hypoxic condition is inseparable from the SUMO modification of a large number of proteins in the cell.It is speculated that enhancing the SUMO modification of the target protein may be one of the molecular mechanisms of the protective effect of mild hypothermia.