PMSCs Cotransplanted With Chitosan-IGF-1C Hydrogel Ameliorate TNBS-Induced Colitis By Secreting PGE2

Background and aims: Mesenchymal stem cells(MSCs)transplantation is a promising strategy for inflammatory bowel disease(IBD).However,low cell retention and engraftment after transplantation diminish the clinical application of MSCs in IBD.In our previous report,a synthesized bioactive hydrogel by immobilizing the C domain peptide of insulin-like growth factor-1(IGF-1C)on chitosan(CS)formed a hydrogel matrix which could refresh stem cells by mimicking niche.Hence we aim to investigate whether co-transplanting this hydrogel with human placenta-derived Mesenchymal stem cells(PMSCs)into the damaged colon could ameliorate trinitrobenzene sulfonic acid(TNBS)-induced colitis and illustrate its mechanism.Methods: Utilizing the lentivirus transfected into PMSCs which steadily express fireflyluciferase(Fluc)and green fluorescent protein(GFP)thereby can be measured proliferation effect of CS-IGF-1C hydrogel for PMSCs and tracked by bioluminescence imaging(BLI)and histology,respectively.Colitis was induced with TNBS via enema,mesenteric injection of PBS,chitosan hydrogel,or chitosan–IGF-1C hydrogel with PMSCs or PBS without PMSCs were performed.After living imaging by BLI for measuring the survival of PMSCs and reactive oxygen species(ROS),intestinal tissues were collected for histopathologic analyses.Proinflammatory cytokines were tested by real time PCR.Western blot and immunofluorescence analyses were conducted for detecting the phenotype of macrophages after transplantation.Enzyme linked immunosorbent assay(ELISA)was performed for testing PGE2 from the supernatant of PMSCs.Results: Comparing with free hydrogel or chitosan hydrogel only,the CS–IGF-1C hydrogel significantly increased stem cell proliferation demonstrated by BLI.Moreover,in vivo studies indicated that CS-IGF-1C hydrogel promoted PMSCs survival confirmed by BLI and co-transplantation of CS-IGF-1C hydrogel with PMSCs ameliorated mice colitis dramatically,increased body weight decreasing IL-1,IL-6 and ROS,alleviated intestinal inflammation,achieved histological improvement compared with free hydrogel or chitosan hydrogel only.Additionally,CS–IGF-1C hydrogel could promote hP-MSC releasing PGE2,polarizing M2 macrophages accompanying expression of Interleukin-10(IL-10),furthermore,reducing the level of M1 macrophages in vitro and in vivo.Conclusions: Topical application of CS-IGF-1C hydrogel implanted PMSCs significantly ameliorates mouse colitis via promoting these donor cells releasing PGE2,which polarizes M2 macrophages accompanying IL-10 expression.