Abstract: Objective To explore the efficient transplantation of bone marrow mesenchymal stem cells (bMSCs) in the treatment of acute severe pancreatitis (SAP) in rats. Methods Rats were randomly divided into control group and acute severe pancreatitis group (by reverse injection of 5% sodium thiocholate in the pancreatic duct). Six hours after the SAP model was successfully produced, it was divided into bone marrow mesenchymal stem cell tail vein transplantation group, intraperitoneal injection transplantation group and tail vein-peritoneal injection combined transplantation group, with 18 rats in each group. Six rats were sacrificed at 24, 48 and 72 h after transplantation, pancreatic tissue and serum were collected, and serum anti-inflammatory factor IL-10 and inflammatory factors IL-1β, TNF-α and IL-6 were measured using Elisa kit. After HE staining, the pathological changes of pancreatic tissue and the intestinal mucosa and alveolar tissue of rats in each group were observed under light microscope. The distribution of DAPI-labeled bMSCs in pancreatic tissue was observed under frozen microscope. Results There were a lot of hemorrhage, edema, inflammatory reaction and necrosis in SAP group. Compared with the control group, hemorrhage, edema, inflammatory reaction and necrosis of pancreatic tissue were significantly decreased in different ways of bMSCs transplantation group(P <0.05), IL-1β, TNF. -α and IL-6 levels were significantly decreased, IL-10 levels were significantly increased (P <0.05);Compared with tail vein transplantation group and intraperitoneal injection transplantation group, hemorrhage, edema, inflammatory response and necrosis were further reduced in the vein + intraperitoneal combined transplantation group (P <0.05), IL -1β, TNF-α and IL-6 levels were further decreased (P <0.05), IL-10 levels were further increased (P <0.05); DAPI-labeled bMSCs were distributed in the pancreatic tissue of the transplanted group, and More fluorescence distribution was observed in the vein + intraperitoneal transplantation group. After 72 hours, the integrity of intestinal mucosa and alveolar tissue in the transplanted group were significantly improved(compared with the SAP group). The neutrophil infiltration and hemorrhage were significantly reduced compared with the SAP group, Compared with intraperitoneal transplantation and simple tail vein transplantation, the combined transplantation group was further improved. Conclusions bMSCs can significantly inhibit inflammatory response and reduce SAP related pancreatic injury, lung injury and small intestinal mucosa injury through tail vein + intraperitoneal transplantation in SD rats of SAP model, and the effect is significantly better than simple tail vein transplantation or intraperitoneal injection.

Key words: Key words: acute severe pancreatitis, bone marrow mesenchymal stem cells, stem cell transplantation.