Cystathionine γ-lyase-H2S facilitates mandibular defect healing via inducing osteogenic differentiation of bone marrow mesenchymal stem cells

Abstract Objective To investigate the effects of endogenous hydrogen sulfide (H2S) synthase, cystathionine-γ-lyase (CSE), on the healing of mandibular defect and the osteogenic differentiation of human mandibular bone marrow mesenchymal stem cells (HM-BMMSCs). Methods Sixty 8-week male C57BL/6 wild-type (WT) mice and CSE knockout (CSE−/−) mice were divided into WT group, CSE−/− group and CSE−/− + GYY4137 (a slow-releasing H2S donor) group. Mandibular defect healing in each group was identified by micro-CT. The histological staining and immunohistochemical staining were adopted to evaluate bone regeneration and reconstruction of mandibular defect. HM-BMMSCs were extracted and cultured for osteogenic induction, which were divided into control group, PAG (a CSE inhibitor) group, GYY4137 group and PAG + GYY4137 group. The mineralization of HM-BMMSCs in each group was determined by alkaline phosphatase (ALP) staining and alizarin red staining. Moreover, mRNA expressions of ALP and Runt-related transcription factor 2 (RUNX2) were detected by RT-PCR. Results Mandibular defect healing in CSE−/− mice was undesirable. When exogenous H2S were supplemented to CSE−/− mice, the new bone mass increased with higher degrees of bone mineralization and bone maturity. Bone mineral density (BMD), bone volume fraction (BV/TV) and bone trabecular thickness (Tb.Th) also significantly increased. in vitro experiments showed that PAG attenuated ALP activity and mineralized nodule formation ability in HM-BMMSCs, and repressed mRNA expressions of ALP and RUNX2. All these osteogenic indexes of HM-BMMSCs were reversed after exogenous H2S was supplemented. Conclusion It is demonstrated that CSE deficiency thwarts the healing of mandibular defect. Blocking the synthesis of H2S inhibits the osteogenic differentiation of HM-BMMSCs, thereby affects bone healing.