Abstract
Background:
Cleft palate is a common developmental disorder in craniofacial region, which cause the severe postnatal oral dysfunction. Mesenchymal stem cell (MSC) therapy has been revealed as a promising therapeutic approach in fetal developmental defects. However, since placental barrier blocks the transfer of cells from maternal circulation, how the MSC exert therapeutic effects and biological function to repair developmental injuries and maintain tissue homeostasis remains elusive.
Methods:
Cyclophosphamide (CP)-induced cleft palate mice were used with replenishment of adipose-derived MSC (ADSC) or apoptotic vesicles (apoVs) derived from MSC, which of cleft palate were characterized by morphological analysis. PKH26 labeling and TUNEL assay were used in tracing of MSC or MSC-derived apoVs. Mechanistical studies were assessed by combinations of RNA-seq analysis, proteomic re-analysis and immunoassay.
Results:
Exogenous MSC recovered the CP-induced cleft palate in E14.5 and E16.5 fetuses. Intriguingly, we unexpectedly found that MSC decreased rapidly and underwent apoptosis in maternal placenta. Accordingly, we assumed MSC-derived apoVs were the mediator of MSC exerting therapeutic effects. MSC-derived apoVs were injected into the pregnant mice and remarkedly improved CP-induced cleft palate, which were traced in fetal multiple organs, particularly in palatine shelves. Mechanistically, transcriptomic and proteomic analysis revealed that MSC-derived apoVs suppressed NLR signaling associated gene expression. Subsequent experimental validation confirmed that MSC-derived apoVs inhibited NLRP3-Caspase-1 mediated pyroptosis in palatal tissues, thereby contributing to the rescue of cleft palate phenotype.
Conclusions:
Our studies revealed exogenous MSC underwent apoptosis and released apoVs to repair fetal cleft palate defects, which mechanistically reduced the NLR signaling mediated pyroptosis in palatal shelves.