Effect of adipose derived mesenchymal stem cells administration and therapeutic induction of hypothermia on delayed neuronal death after transient global cerebral ischemia

Abstract

Background: Global cerebral ischemia is the most important cause of poor prognosis after successful resuscitation from cardiac arrest. Therapeutic induction of hypothermia (maintenance of core body temperature between 32℃ and 34℃ for 12 to 24 hr, TH) has shown its efficacy in reduction of the neurologic damage from global cerebral ischemia through various laboratory and clinical researches, and it is recommended as one of the standard post-resuscitation managements. However, alternatives or complements for TH are necessary due to its technical difficulty in induction of recommended temperature and keeping recommended rate of rewarming, which limits the application of TH. We aimed to show the effect of stem cell on the neurologic recovery after transient global cerebral ischemia including the comparison with that of current standard therapy, TH.Materials and methods: Rats were subjected to 7 min of transient global cerebral ischemia and randomized into 4 intervention groups: placebo control, TH, human mesenchymal stem cell (MSC), and combined TH and MSC, along with 4 sham operation groups with same intervention. Hippocampal neuronal death was evaluated at 7 days after ischemia by Fluoro Jade B staining. Activated microglia and infiltrating macrophages were evaluated at 7 days after ischemia by immunostaining for CD11b. IgG immunostaining was performed to detect blood brain barrier (BBB) disruption, and myeloperoxidase (MPO) immunostaining was done to detect neutrophil infiltration in the hippocampus. 4HNE immunostaining was performed to detect oxidative injury. The time until the animal removed adhesive tapes on their both forepaws was measured to test the behavioral function, a week after the insult.Results: No degenerating neuron was detected by Fluoro-Jade B staining in any of the sham operation groups. Analysis of variance (ANOVA) showed significant differences in degenerating neuron count among 4 ischemia induced groups at CA1, CA3, and hilus region (p= <0.001, 0.004, and 0.033, respectively). Post hoc analysis revealed significant differences: between control and TH, between control and MSC, and between control and TH/MSC in CA1; between control and MSC, and between control and TH/MSC in CA3; between control and MSC in hilus. Significant difference in microglial activation was found among 8 sham operation and ischemia groups through ANOVA (p<0.001). Post hoc analysis showed: no significant difference among 4 sham operation groups (control, TH, MSC, and TH/MSC with sham operation); significant differences between sham groups and control, between sham groups and TH, between sham MSC and MSC, between control and TH, between control and MSC, between control and TH/MSC, between TH and MSC, and between TH and TH/MSC. ANOVA showed a significant difference in IgG leakage among 8 sham operation and ischemia groups (p<0.001). Post hoc analysis revealed: no significant difference among 4 sham operation groups; significant differences between sham groups and control, between control and TH, between control and MSC, and between control and TH/MSC. ANOVA failed to show a significant difference in MPO(+) cell count among 8 sham operation and ischemia groups (p=0.052). Significant difference in 4HNE intensity was found among 8 sham operation and ischemia groups through ANOVA (p<0.001). Post hoc analysis showed: no significant difference among 4 sham operation groups; significant differences between sham groups and control, between sham groups and TH, between control and TH, between control and MSC, between control and TH/MSC, between TH and MSC, and between TH and TH/MSC. Significant difference of the time spent to detach the adhesive tapes on forepaws among 5 normal and ischemia groups was found through ANOVA (p<0.001), and post hoc analysis showed the differences between placebo controlled ischemia group and other groups.Conclusions: Administration of MSC after transient global cerebral ischemia has a prominent protective effect on delayed hippocampal neuron death comparing with TH, current standard treatment option. The present results also suggest combined treatment of MSC and hypothermia warrants a potential therapeutic strategy for intervention of global cerebral ischemia after cardiac arrest.