Abstract: Objective To investigate the effect of adipose derived mesenchymal stem cells (ADSCs) on autophagy in rats with intracerebral hemorrhage (ICH) and to explore the possible mechanism of action. 
Methods The periinguinal fat of healthy SD rats was isolated in a sterile environment, and ADSCs were cultured in vitro and cultured to the fourth generation. The surface markers of ADSCs were measured by flow cytometry. Male SD rats were randomly divided into three groups: Sham operation group (Sham group), ICH group, and ADSCs group. ICH models were established in the ICH group and ADSCs group, and the same method was used for model establishment for Sham group, but autologous blood was not injected. At 2 h after successful modeling surgery, the ADSCs group was given a 5 μL cell suspension (1×105 cells) by injection into the right striatal region, while an equal volume of saline was given in the Sham and ICH groups. Rats received nerve function evaluation by the Longa scores at 12 h, 1 d, 3 d, 5 d, and 7 d after successful modeling. After the rats were sacrificed, the pathological changes of brain tissue were observed by hematoxylin-eosin staining, the number of undamaged neurons was observed by Nissl staining, and the water content of brain tissue was measured. Intracellular autophagy-related proteins were detected by immunohistochemical staining, including recombinant human Beclin 1 (Beclin1) and microtubule-Associated Protein 1 Light Chain 3 (LC3), as well as the expression of the phosphorylation of the serine/threonine protein kinase AKT/mammalian target of rapamycin (AKT/mTOR) signaling pathway. Western Blot was used to detect the expression of LC3, Beclin1 and AKT/mTOR signaling pathway-related proteins in the brain tissue at 1 d and 3 d after modeling. 
Results The flow cytometry found positive expression of adhesion molecules CD29 and CD90 and negative expression of CD45 in ADSCs of cultured rats. Compared with the Sham group, the histopathological symptoms of the rat brain were significantly increased, Longa score, brain water content, number of damaged neurons, autophagy-related proteins LC3 and Beclin1 in ICH group were significantly up-regulated, and the expression of AKT/mTOR signaling pathway phosphorylation positive cells and the protein expression were significantly increased. Compared with ICH group, the histopathological symptoms of the rat brain were significantly relieved, while Longa score, brain water content and the number of damaged neurons in ADSCs group were decreased significantly (P＜0.05). The expression of autophagy-related proteins LC3 and Beclin1 was decreased significantly (P＜0.05), while the expression of AKT/mTOR signaling pathway phosphorylation positive cells and the protein expression were increased significantly (P＜0.05). 
Conclusion ADSCs transplantation can exert a neuroprotective effect in the treatment of ICH, which may inhibit the level of autophagy in ICH rats by activating AKT/mTOR signal pathway, so as to reduce the degree of brain injury in rats. 

Key words: cerebral hemorrhage, mesenchymal stem cells, autophagy