Exosomes derived from hUC-MSCs exhibit ameliorative efficacy upon previous cesarean scar defect via orchestrating β-TrCP/CHK1 axis.

Previous cesarean scar defect (PCSD), also acknowledged as the myometrium of uterus defects, which commonly results in myometrial discontinuity between the uterine and cervical cavity. Current literatures have indicated the efficacy of MSCs and MSC-derived exosomes (MSC-Exos) for diverse refractory disease administration, yet the feasibility of MSC-Exos for PCSD treatment is largely obscure. In this study, we took advantage of the in vivo myofibrotic model for mimicking the typical manifestation of PCSD and the assessment of fertility. Meanwhile, the ex vivo scratch wound healing model is used for exploring the underlying molecular mechanism. On the one hand, we took advantage of the TGF-β-induced in vitro myofibrotic model and the full-thickness uterine injury rat model to verify the efficacy of human umbilical cord MSC-derived exosomes (hUC-MSC-Exos). On the other hand, with the aid of CHK1 overexpression and β-TrCP knockdown, together with multifaceted biological analyses (e.g., histopathological sections, qRT-PCR assay, western-blotting analysis, Co-IP assay, protein degradation and ubiquitination), we further dissected the underlying regulatory mechanism. We identified hUC-MSC-Exos and verified the suppressive effect of hUC-MSC-Exos upon TGF-β-induced in vitro myofibrotic model and full-thickness uterine injury in rats via delivering β-TrCP. Furthermore, we found that β-TrCP in hUC-MSC-Exos facilitated the ubiquitination degradation of CHK1 and inhibited the myofibrosis. Collectively, our data indicated the preferable ameliorative effect of hUC-MSC-Exos upon both the in vitro and in vivo myofibrotic models, together with the β-TrCP and CHK1-mediated regulatory mechanism. Our findings provided new references of hUC-MSC-Exos-based regimens for PCSD management in future.