Protective effect of placental mesenchymal stem cells on lung injury in rats with severe acute pancreatitis and its mechanism

Objective To investigate the protective effect and mechanism of placental-derived mesenchymal stem cells (P-MSCs) on lung injury in rats with severe acute pancreatitis. Methods A total of 36 healthy adult male SD rats were randomly divided into control group (n=12), SAP group (n=12) and P-MSCs group (n=12). SAP rat model was established by retrograde injection of 4% sodium taurocholate into biliopancreatic duct. P-MSCs (1×10⁶ cells/100 g) were delivered through the tail vein of the rats at 6 h after the induction of SAP. The rats were sacrificed 12 and 24 h after P-MSCs infusion. The ratio of wet to dry weight of lung tissue and the number of neutrophils, leukocytes and macrophages in bronchoalveolar lavage fluid (BALF) was calculated. The degree of pancreatic and lung injury was evaluated by HE staining. The concentration of amylase, lipase and inflammatory factors in serum was measured by ELISA. The MPO activity in pancreas and lung tissue was measured by MPO assay kit, and the mRNA expression levels of TNF-α, IL-1β in lung tissue were detected by RT-qPCR. The ratio of M1 and M2 in lung tissue was detected by immunofluorescence stain. Results Compared with SAP group, the ratio of wet to dry weight of lung tissue in P-MSCs group significantly decreased, the number of neutrophils, leukocytes and macrophages in BALF were significantly reduced (P