This observation was unexpected. However it is most likely related to the differences in study design between this current study and the ones previously published where the Ex-4 treatment was initiated before or at the time of stroke and the effect on stroke size was dramatic. It is plausible, that the previously observed anti-inflammatory effects by Ex-4 were secondary to the reduced 4-Chloro-7H-pyrrolo[2,3-d]pyrimidine injury size, GSK2879552 rather than being a direct consequence of anti-inflammatory effects of Ex-4. Our in vitro data further support this by showing no effect of Ex-4 on LPS-induced inflammation in cultured microglia. Similar to that shown after both spinal cord injury and focal cerebral ischemia, we found an increased expression of both M1 and M2 markers 3 days after MCAO. Administration of Ex-4 had no effect on the M1 markers. In contrast, Ex-4 increased the expression of M2 markers after MCAO. It has been suggested that the microglial M2 phenotype has a reparative function and could promote CNS repair. Further, we have previously shown that increased vulnerability after brain injury was associated with a decrease in reparative M2 microglia. The increased expression of M2 markers by Ex-4 indicates that Ex-4 enhances the polarization towards the reparative M2 phenotype, suggesting a novel mechanism at the basis of the neuroprotective efficacy mediated by Ex-4. This mechanism based on M2 repair could also contribute to the larger therapeutic window observed in our study in comparison to that reported by Taramoto et al. In the latter study, the mice received Ex-4 only once before being sacrificed 24 hours thereafter. Vice versa, in our study we continued with daily treatments of Ex-4 for several days, thus potentially maximizing the Ex-4-mediated M2 reparative phenotype. In conclusion, we show that Ex-4 mediates neuroprotection against stroke in normal and aged T2D/obese mice. The results were achieved by using a preclinical experimental paradigm with potential relevance for the treatment of stroke patients in the prehospital or early hospitalization settings. The results also suggest that one of the contributing mechanisms at the basis of Ex-4 neuroprotection may be enhancing the reparative M2 phenotype.