Hypoxia-preconditioned human dental pulp stem cells transplantation alleviates hypoxic-ischemic brain damage via STAT3/NLRP3/Caspase-1 axis in neonatal rats

This study was conducted to examine the effects and mechanisms of hypoxia-preconditioned human dental pulp stem cells (H-hDPSCs) transplantation on microglial pyroptosis in neonatal rats with hypoxic-ischemic brain damage (HIBD). The hDPSCs were extracted using the tissue block method and identified by immunofluorescence staining. The HIBD model was constructed using the classical Rice-Vannucci method. 24 h after HIBD, normoxic preconditioning hDPSCs (N-hDPSCs) and H-hDPSCs were transplanted into the lateral ventricle. The brain damage was examined by hematoxylin & eosin and Nissl stainings 72 h after transplantation. The expression of signal transducer and activator of transcription 3 (STAT3)/NOD-like receptor family pyrin domain-containing 3 (NLRP3)/Caspase-1 axis-related proteins was analyzed by immunofluorescence staining and western blots. Tissue levels of interleukin-1 beta (IL-1β) were derived from ELISA. After modeling, the neural cells in the HIBD group were disordered and sparsely scattered, with a deficiency of nitrosamines. The data revealed that the phosphorylated STAT3, NLRP3, Cleaved-Caspase 1, N-terminal fragment of gasdermin D (GSDMD-N), and IL-1β protein expression were significantly lower in the H-hDPSCs and N-hDPSCs groups compared to the HIBD group. The protein expression in the H-hDPSCs group was considerably lower than in the N-hDPSCs group. H-hDPSCs may protect microglia from pyroptosis by regulating the STAT3/NLRP3/Caspase-1/GSDMD axis to alleviate inflammatory damage, and attenuate HIBD in newborn rats at the same time. Moreover, the therapeutic effect of H-hDPSCs transplantation was superior to that of N-hDPSCs transplantation.