Conditioned medium obtained from human amniotic mesenchymal stem cells attenuates focal cerebral ischemia/reperfusion injury in rats by targeting mTOR pathway

Abstract

Conditioned medium obtained from human amniotic mesenchymal stem cells (hAMSC-CM) was recently shown to have many antioxidant, antiapoptotic and proangiogenic growth factors. The present study was performed to investigate whether protective effects of hAMSC-CM against focal cerebral ischemia/ reperfusion (I/R) injury is associated with modulation of the mammalian target of rapamycin (mTOR) pathway.A rat model of middle cerebral artery occlusion (MCAO) was created and the animals were divided into three groups including sham, MCAO and MCAO + hAMSC-CM. Drug was administrated immediately after cerebral reperfusion (i.v). The expressions of mTOR, p-mTOR and LC3 were measured using Western blotting and real time-PCR, respectively. Apoptosis and neuronal loss were determined using TUNEL and Nissl staining, respectively. Infarct volume and the blood–brain barrier (BBB) damage were evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining and Evans Blue (EB) uptake, respectively.Compared with sham, significant infarct volume, apoptotic cell death, and neuronal loss were found in MCAO rats that reversed by hAMSC-CM (P < 0.05). Likewise, MCAO rats exhibited increased mRNA level of light-chain 3 (LC3) and the LC3II/LC3I ratio as well as decreased expression level of p-mTOR that reversed by hAMSC-CM (P < 0.05). There were no significant differences in the expression of total mTOR among the experimental groups.In summary, our results demonstrate that hAMSC-CM gives rise to neuroprotection following ischemic stroke by restoring mTOR activity and inhibiting autophagy.