Platelet-rich fibrin promotes mesothelial cell proliferation and peritoneal repair by up-regulating calretinin to prevent postoperative intestinal adhesion

<b>Introduction:</b> As the most common postoperative complication, intestinal adhesions can cause intestinal obstruction, female infertility, and even endanger life. The currently developed materials for preventing intestinal adhesions mainly focus on physical barriers and reducing inflammatory reactions, while neglecting the importance of effectively promoting rapid repair of the peritoneum. We previously found that platelet-rich fibrin (PRF) can prevent postoperative intestinal adhesions. The proliferation of mesothelial cells may play a significant role in reducing intestinal adhesions, but the mechanism remains unclear. A study found a positive correlation between calretinin (CR) and mesothelial cell proliferation. Does CR play an important role in PRF promoting mesothelial cell proliferation? This study aims to further explore the mechanism of PRF in preventing intestinal adhesions. <b>Methods:</b> Primary mouse peritoneal mesothelial cells and mouse peritoneal fibroblasts were used in this study. The effects of PRF on the proliferation and attachment of mesothelial cells and fibroblasts were observed and compared using the CCK-8 assay, Edu assay, and laser scanning confocal microscope. The effects of PRF on the migration of mesothelial cells were examined using scratch and transwell migration assays. The effects of PRF on the mesothelial-mesenchymal transition (MMT) of mesothelial cells were examined using western blot. The expression level of CR in mesothelial cells was detected through immunofluorescence, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot. <b>Results:</b> PRF promotes mesothelial cell proliferation from 1st day and significantly promotes fibroblast proliferation from 7th day. Meanwhile, PRF tends to promote the proliferation and attachment of mesothelial cells rather than fibroblasts. However, PRF had a limited regulatory effect on the MMT of mesothelial cells. In addition, PRF can promote mesothelial cell migration and upregulate the expression level of CR. <b>Conclusion:</b> PRF promotes mesothelial cell proliferation and migration, as well as peritoneal repair, by up-regulating CR in the early stages of peritoneal injury to prevent postoperative intestinal adhesion. Its mechanism is obviously different from that of traditional anti-adhesion materials, which will provide new strategies for the prevention of intestinal adhesions.