Comparison of the therapeutic effect of native and preconditioned human umbilical cord-derived multipotent mesenchymal stromal cells on a rat model of acute pancreatitis
Authors:   Institute of Molecular Biology and Genetics, National Academy of Sciences of Ukraine, Kyiv, Ukraine, Pikus Polina ,   Institute of Genetic and Regenerative Medicine, M. D. Strazhesko National Scientific Center of Cardiology, Clinical and Regenerative Medicine, National Academy of Medical Sciences of Ukraine, Kyiv, Ukraine, Rymar Svitlana , Pustovalov Andriy ,   Educational and Scientific Center “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine, Shuvalova Nadiia , Reshetnyk Ye , Kordium Vitalii 
Published: November 2023

Pancreatitis is a disease characterized by an acute or chronic inflammatory process of the pancreas, induced by the activation of trypsin inside acinocytes. These processes result in necrosis of the organ's parenchyma, abscess formation, and systemic complications, contributing to patient mortality rates ranging from 30-47%. As of now, there is no globally recognized effective treatment for acute pancreatitis. Multipotent mesenchymal stem cells (MMSCs) are potential candidates for treating this disease due to their immunomodulatory properties. The aim of this study was to compare the therapeutic effects of transplanting native human umbilical cord-derived MMSCs (hUC-MMSCs) with hUC-MMSCs preconditioned with H2O2 in a rat model of acute pancreatitis. Materials and methods. Acute pancreatitis in rats was induced by intraperitoneal injection of L-arginine at a dose of 3.5 g/kg body weight at an interval of 1 hour. The rats were then categorized into four groups. Group 1 – negative control, where animals received a physiological solution; group 2 – positive control (pancreatitis). Three days after the onset of signs of developed acute pancreatitis, group 3 rats were intraperitoneally transplanted with native hUC-MMSCs, meeting the minimum criteria of the International Society for Cell and Gene Therapy, at a dose of 1.5×106 cells/kg. Group 4 received the same dose of hUC-MMSCs, but these cells were preconditioned with H2O2 at a concentration of 30 µM for 18 hours. The effects of both native and preconditioned hUC-MMSCs were evaluated at 3, 7, and 14 days after their introduction. Assessment criteria included the α-amylase index, identification of insulin in the islets of Langerhans, and histological analysis. Results. It was demonstrated that, three days post L-arginine administration, the α-amylase level surged by five times compared to the negative control, and blood glucose levels increased by 2.5 times, indicating damage to both the exocrine and endocrine parts of the pancreas. Microscopic examination revealed a 3.5-fold increase in fibrosis of the pancreatic parenchyma compared to the negative control. Three days after the transplantation of native hUC-MMSCs, the α-amylase level in the blood decreased by 1.7 times, and in the variant with preconditioned hUC-MMSCs, it decreased by 2 times compared to Group 2. By day 7, the α-amylase index in the native hUC-MMSCs group decreased by 2.4 times compared to the positive control, and in the preconditioned hUC-MMSCs group, it approached normal levels. A gradual recovery of the pancreatic architecture was observed by day 7, with a faster recovery in the preconditioned MMSCs group. Histological sections revealed a replacement of nuclei-free areas with acinocytes, indicated by a 3-fold decrease in the number of nuclei-free cells in the native hUC-MMSCs transplantation, and almost normal levels in the preconditioned hUC-MMSCs group. Both variants exhibited a positive histochemical PAS-reaction for the identification of insulin in the islets of Langerhans, and blood glucose levels corresponded to the norm. After 14 days, complete recovery of the pancreas was observed in both variants.	Conclusion. The study results indicate that hUC-MMSCs transplantation in rats with acute pancreatitis contributes to the restoration of pancreatic parenchyma architecture and function. Moreover, the administration of MMSCs preconditioned with H2O2 significantly enhances the therapeutic effect, expediting the recovery process of the pancreas in animals.