Abstract: 【Objective】 The aim of this study was to explore the protective mechanism of adipose-derived stem cells conditioned medium (ADSCs-CM) in alleviating pancreatic oxidative stress injury induced by sodium taurocholate and trypsin.【Method】 One Chinese garden dog was selected to isolate and culture adipose-derived stem cells (ADSCs) and prepare conditioned medium (CM). Nine dogs were randomly divided into control group (CON group),AP model group (AP group) and CM treatment group (CM group).The AP and CM groups were retrogradely injected with a mixture of 5% sodium taurocholate (0.1 mL/kg) and trypsin (3500 U/kg) through the pancreaticobiliary duct to establish a AP model,The CON group was injected with the same volume of normal saline.After surgery, CM group was intravenously injected with ADSCs-CM(0.1 mL/kg),the CON group and AP group were injected with the same volume of normal saline.Blood and pancreatic tissue samples were collected 24 h after surgery,histopathology,B-ultrasound,canine pancreas-specific lipase (cPL),blood routine,biochemical indexes were detected 24 hours after operation,and the levels of total nitric oxide synthase (T-NOS),inducible nitric oxide synthase (i-NOS),glutathione (GSH) and glutathione peroxidase (GPx) in pancreas and serum were detected by colorimetry.【Result】 B-ultrasound showed that the pancreas echo in AP group and CM group was uneven,the surrounding fat was hyperechoic. Pathological tissue sections showed that the pancreatic swelling and hemorrhage,peripheral steatosis,severe duodenal hemorrhage,interstitial edema,a large number of cell necrosis and inflammatory cell infiltration,and severe hemorrhage of pancreas were occurred in the AP group.The histopathological changes of pancreas and surrounding tissues in the CM group were milder than that of in the AP group. The cPL tests were all positive.Compared with the CON group,the contents of Cl^-,ALB,GLB and TP in the AP group decreased significantly (P＜0.05),while the activities of AMY,LIPA,plasma T-NOS,pancreatic i-NOS and T-CHO,GSH contents increased significantly (P＜0.05).In the CM group,the contents of Na⁺,Cl^-,GLB and TP decreased significantly (P＜0.05),while the activities of AMY,pancreatic GPx,and the contents of plasma GSH,pancreatic GSH increased significantly (P＜0.05).Compared with the AP group,the contents of TCO₂,Na⁺,Cl^-,ALB,TCHO and plasma T-NOS activity in the CM group decreased significantly (P＜0.05),pancreatic GPx activity and plasma GSH content increased significantly (P＜0.05).【Conclusion】 ADSCs-CM could reduce the degree of pancreatic injury in AP model dogs,and the protective mechanism was closely related to the decrease of plasma T-NOS activity and the increase of pancreatic GPx and plasma GSH levels.This study could provide a theoretical basis for the treatment of AP and the application of ADSCs-CM.

Key words: canine; acute pancreatitis; adipose-derived stem cell conditioned medium; oxidative stress