Mechanical force increases tooth movement and promotes remodeling of alveolar bone defects augmented with bovine bone mineral.

BACKGROUND: Orthodontic tooth movement (OTM) in a region containing alveolar bone defects with insufficient height and width is hard to achieve. Bovine bone mineral (Bio-Oss) is available to restore the alveolar defect; however, whether the region augmented with a bovine bone mineral graft (BG) is feasible for OTM, and the mechanisms by which macrophages remodel the BG material, is uncertain under the mechanical force induced by OTM. MATERIAL AND METHODS: Rats were divided into three groups: OTM (O), OTM + BG material (O + B), and Control (C). First molars were extracted to create bone defects in the O and O + B groups with bovine bone mineral grafting in the latter. Second molars received OTM towards the bone defects in both groups. After 28 days, maxillae were analyzed using microfocus-computed tomography (µCT) and scanning-electron-microscopy (SEM); and macrophages (M1/M2) were stained using immunofluorescence. THP-1 cell-induced macrophages were cultured under mechanical force (F), BG material (B), or both (F + B). Phagocytosis-related signaling molecules (cAMP/PKA/RAC1) were analyzed, and conditioned media was analyzed for MMP-9 and cytokines (IL-1ß, IL-4). RESULTS: Our study demonstrated that alveolar defects grafted with BG materials are feasible for OTM, with significantly increased OTM distance, bone volume, and trabecular thickness in this region. SEM observation revealed that the grafts served as a scaffold for cells to migrate and remodel the BG materials in the defect during OTM. Moreover, the population of M2 macrophages increased markedly both in vivo and in cell culture, with enhanced phagocytosis via the cAMP/PKA/RAC1 pathway in response to mechanical force in combination with BG particles. By contrast, M1 macrophage populations were decreased under the same circumstances. In addition, M2 macrophage polarization was also indicated by elevated IL-4 levels, reduced IL-1ß levels, and less active MMP-9 in cell culture. CONCLUSION: This study explored the mechanisms of mechanical force-induced alveolar bone remodeling with bovine bone mineral grafts during OTM. The results might provide molecular insights into the related clinical problems of whether we can move teeth into the grafted materials; and how these materials become biologically remodeled and degraded under mechanical force.

Stem Cells from Human Exfoliated Deciduous Teeth Alleviate High-Altitude Cerebral Oedema by Shifting Microglial M1/M2 Polarisation.

OBJECTIVE: To explore the high-efficiency and low-risk prevention and treatment strategies for stem cells from human exfoliated deciduous teeth (SHED) for high-altitude cerebral oedema. METHODS: A low-pressure and low-oxygen tank mimicking high-altitude conditions was used to establish the high-altitude cerebral oedema animal model. The preventive effects of SHED for cerebral oedema were then evaluated by haematoxylin and eosin (H&E) and histological staining. In vitro, SHED was co-cultured with BV-2 to analyse the effects of SHED by western blot and immunofluorescence staining. RESULTS: SHED can prevent and treat cerebral oedema in a high altitude rat animal model. Mechanistically, SHED treatment can protect brain cells from apoptosis induced by high altitude condition. Moreover, SHED treatment can inhibit M1-type polarisation and promote M2-type polarisation of microglia cells via the suppression of hypoxia inducible factor (HIF)- 1α-mediated extracellular signal-regulated kinase (ERK) signalling activated in high altitude condition. CONCLUSION: SHED treatment can relieve high-altitude cerebral oedema via inhibiting HIF- 1α-mediated ERK signalling, which indicates that SHED is a promising alternative strategy to prevent and treat high-altitude cerebral oedema.

Stem Cells From Human Exfoliated Deciduous Teeth Alleviate Liver Cirrhosis via Inhibition of Gasdermin D-Executed Hepatocyte Pyroptosis.

Liver cirrhosis represents a type of end-stage liver disease with few effective therapies, which was characterized by damaged functional liver tissue due to long-term inflammation. Gasdermin D (GSDMD)-executed programmed necrosis is reported to be involved in inflammation. However, the role of GSDMD in liver cirrhosis remains unclear. In this study, we used a CCl4-induced cirrhosis model and found stem cells from human exfoliated deciduous teeth (SHED) infusion showed profound therapeutic effects for liver cirrhosis. Mechanistically, NLRP3 inflammasome-activated GSDMD and its pyroptosis were upregulated in liver cirrhosis, while SHED infusion could suppress the expression of GSDMD and Caspase-1, resulting in reduced hepatocyte pyroptosis and inflammatory cytokine IL-1ß release. Consistently, SHED could inhibit the elevated expression of NLRP3, GSDMD and Caspase-1 induced by CCl4 treatment in vitro co-culture system, which was mediated by decreasing reactive oxygen species (ROS) generation. Moreover, the pyroptosis inhibitor disulfiram showed similar therapeutic effects for liver cirrhosis as SHED. In conclusion, SHED alleviates CCl4-induced liver cirrhosis via inhibition of hepatocytes pyroptosis. Our findings could provide a potential treatment strategy and novel target for liver cirrhosis.