A five-in-one novel MOF-modified injectable hydrogel with thermo-sensitive and adhesive properties for promoting alveolar bone repair in periodontitis: Antibacterial, hemostasis, immune reprogramming, pro-osteo-/angiogenesis and recruitment.

Periodontitis is a chronic inflammatory disease caused by plaque that destroys the alveolar bone tissues, resulting in tooth loss. Poor eradication of pathogenic microorganisms, persistent malignant inflammation and impaired osteo-/angiogenesis are currently the primary challenges to control disease progression and rebuild damaged alveolar bone. However, existing treatments for periodontitis fail to comprehensively address these issues. Herein, an injectable composite hydrogel (SFD/CS/ZIF-8@QCT) encapsulating quercetin-modified zeolitic imidazolate framework-8 (ZIF-8@QCT) is developed. This hydrogel possesses thermo-sensitive and adhesive properties, which can provide excellent flowability and post-injection stability, resist oral fluid washout as well as achieve effective tissue adhesion. Inspirationally, it is observed that SFD/CS/ZIF-8@QCT exhibits a rapid localized hemostatic effect following implantation, and then by virtue of the sustained release of zinc ions and quercetin exerts excellent collective functions including antibacterial, immunomodulation, pro-osteo-/angiogenesis and pro-recruitment, ultimately facilitating excellent alveolar bone regeneration. Notably, our study also demonstrates that the inhibition of osteo-/angiogenesis of PDLSCs under the periodontitis is due to the strong inhibition of energy metabolism as well as the powerful activation of oxidative stress and autophagy, whereas the synergistic effects of quercetin and zinc ions released by SFD/CS/ZIF-8@QCT are effective in reversing these biological processes. Overall, our study presents innovative insights into the advancement of biomaterials to regenerate alveolar bone in periodontitis.

An injectable and coagulation-independent Tetra-PEG hydrogel bioadhesive for post-extraction hemostasis and alveolar bone regeneration.

Effective control of post-extraction hemorrhage and alveolar bone resorption is critical for successful extraction socket treatment, which remains an unmet clinical challenge. Herein, an injectable Tetra-PEG hydrogel that possesses rapid gelation, firm tissue adhesion, high mechanical strength, suitable degradability, and excellent biocompatibility is developed as a sutureless and coagulation-independent bioadhesive for the management of extraction sockets. Our results demonstrate that the rapid and robust adhesive sealing of the extraction socket by the Tetra-PEG hydrogel can provide reliable protection for the underlying wound and stabilize blood clots to facilitate tissue healing. In vivo experiments using an anticoagulated rat tooth extraction model show that the hydrogel significantly outperformed clinically used cotton and gelatin sponge in hemostatic efficacy, wound closure, alveolar ridge preservation, and in situ alveolar bone regeneration. Histomorphological evaluations reveal the mechanisms for accelerated bone repair through suppressed long-term inflammation, elevated collagen deposition, higher osteoblast activity, and enhanced angiogenesis. Together, our study highlights the clinical potential of the developed injectable Tetra-PEG hydrogel for treating anticoagulant-related post-extraction hemorrhage and improving socket healing.

Active targeting microemulsion-based thermosensitive hydrogel against periodontitis by reconstructing Th17/Treg homeostasis via regulating ROS-macrophages polarization cascade.

Periodontitis is a multifactorial inflammatory disease characterized by severe alveolar bone damage and attachment loss. The imbalance of T help 17 (Th17) / regulatory T cells (Treg) induces excessive interleukin (IL)-17, which leads to alveolar bone damage and aggravates the development of periodontitis. Therefore, we proposed a therapeutic strategy to restore Th17/Treg homeostasis by interfering reactive oxygen species (ROS)-macrophage polarization cascade using active targeting microemulsions-based thermosensitive hydrogel. Folic acid-modified quercetin-loaded microemulsions (FA-Qu-MEs) were dispersed in poloxamer 407 and poly(N-isopropylacrylamide) matrix of hydrogel (FA-Qu-MEs@Gel). FA-Qu-MEs@Gel could be locally injected into the periodontal pocket and sustainedly release drugs. FA-Qu-MEs exhibited excellent ROS scavenging potency by targeting macrophages, resulting M1 phenotype macrophage from to M2 phenotype macrophage. Subsequently, the phenotypic changes of macrophages lead to decreased expression of IL-6 and tumor necrosis factor-α, which inhibited activated Th17, while IL-10 secreted by M2 macrophages promoted Treg differentiation. Finally, the restored Th17/Treg homeostasis reduced the level of IL-17 to accelerate alveolar bone regeneration. This study deigns a novel system that promote alveolar bone regeneration by remodeling Th17/Treg homeostasis via regulating ROS-macrophages polarization cascade for periodontitis treatment.

Multifunctional Nanofibrous Hollow Microspheres for Enhanced Periodontal Bone Regeneration.

Destructive periodontitis destroys alveolar bone and eventually leads to tooth loss. While guided bone regeneration, which is based on creating a physical barrier to hinder the infiltration of epithelial and connective tissues into defect sites, has been widely used for alveolar bone regeneration, its outcomes remain variable. In this work, a multifunctional nanofibrous hollow microsphere (NFHMS) is developed for enhanced alveolar bone regeneration. The NFHMS is first prepared via combining a double emulsification and a thermally induced phase separation process. Next, E7, a short peptide with high specific affinity to bone marrow-derived stem cells (BMSCs), is conjugated onto the surface of NFHMS. After that, bone forming peptide (BFP), a short peptide derived from bone morphology protein 7 is loaded in calcium phosphate (CaP) nanoparticles, which are further encapsulated in the hollow space of the NFHMS-E7 to form NFHMS-E7-CaP/BFP. The NFHMS-E7-CaP/BFP selectively promoted the adhesion of BMSCs and expelled the adhesion of fibroblasts and epithelial cells. In addition, the BFP is sustainedly released from the NFHMS-E7-CaP/BFP to enhance the osteogenesis of BMSCs. A rat challenging fenestration defect model showed that the NFHMS-E7-CaP/BFP significantly enhanced alveolar bone tissue regeneration. This work provides a novel bioengineering approach for guided bone regeneration.

RNA Technology to Regenerate and Repair Alveolar Bone Defects.

microRNA-200a (miR-200a) targets multiple signaling pathways that are involved in osteogenic differentiation and bone development. However, its therapeutic function in osteogenesis and bone regeneration remains unknown. In this study, we use in vitro and in vivo models to investigate the molecular function of miR-200a overexpression and miR-200a inhibition using a plasmid-based miR inhibitor system (PMIS) on osteogenic differentiation and bone regeneration. Inhibition of miR-200a using PMIS-miR-200a significantly increased osteogenic biomarkers of human embryonic palatal mesenchyme cells and promoted bone regeneration in rat tooth socket defects. In rat maxillary M1 molar extractions, the supporting tooth structures were removed with an implant drill to yield a 3-mm defect in the alveolar bone. A collagen sponge was inserted into the open alveolar defect and PMIS-miR-200a plasmid DNA was added to the sponge and the wound sutured to protect the sponge and close the defect. It was important to remove the existing tooth supporting structure, which can influence alveolar bone regeneration. The alveolar bone was regenerated in 4 wk. The collagen sponge acts to stabilize and deliver the PMIS-miR-200a DNA to cells entering the sponge in the bone defect. We show that mesenchymal stem cells expressing CD90 and Stro-1 enter the sponges, take up the DNA, and express PMIS-miR-200a. PMIS-miR-200a initiates a bone regeneration program in transformed cells in vivo. In vitro inhibition of miR-200a was found to upregulate Wnt and BMP signaling activity as well as Runx2, OCN, Lef-1, Msx2, and Dlx5 associated with osteogenesis. Liver and blood toxicity testing of PMIS-miR-200a-treated rats showed no increase in several biomarkers of liver disease. These results demonstrate the therapeutic function of PMIS-miR-200a for rapid bone regeneration. Furthermore, the studies were designed to demonstrate the ease of use of PMIS-miR-200a in solution and applied using a syringe in the clinic through a simple one-time application.

Recent Advances in Scaffolds for Guided Bone Regeneration.

The rehabilitation of alveolar bone defects of moderate to severe size is often challenging. Currently, the therapeutic approaches used include, among others, the guided bone regeneration technique combined with various bone grafts. Although these techniques are widely applied, several limitations and complications have been reported such as morbidity, suboptimal graft/membrane resorption rate, low structural integrity, and dimensional stability. Thus, the development of biomimetic scaffolds with tailor-made characteristics that can modulate cell and tissue interaction may be a promising tool. This article presents a critical consideration in scaffold's design and development while also providing information on various fabrication methods of these nanosystems. Their utilization as delivery systems will also be mentioned.

Quercetin-loaded mesoporous nano-delivery system remodels osteoimmune microenvironment to regenerate alveolar bone in periodontitis via the miR-21a-5p/PDCD4/NF-κB pathway.

BACKGROUND: Impaired osteo-/angiogenesis, excessive inflammation, and imbalance of the osteoimmune homeostasis are involved in the pathogenesis of the alveolar bone defect caused by periodontitis. Unfortunately, there is still a lack of ideal therapeutic strategies for periodontitis that can regenerate the alveolar bone while remodeling the osteoimmune microenvironment. Quercetin, as a monomeric flavonoid, has multiple pharmacological activities, such as pro-regenerative, anti-inflammatory, and immunomodulatory effects. Despite its vast spectrum of pharmacological activities, quercetin's clinical application is limited due to its poor water solubility and low bioavailability. RESULTS: In this study, we fabricated a quercetin-loaded mesoporous bioactive glass (Quercetin/MBG) nano-delivery system with the function of continuously releasing quercetin, which could better promote the bone regeneration and regulate the immune microenvironment in the alveolar bone defect with periodontitis compared to pure MBG treatment. In particular, this nano-delivery system effectively decreased injection frequency of quercetin while yielding favorable therapeutic results. In view of the above excellent therapeutic effects achieved by the sustained release of quercetin, we further investigated its therapeutic mechanisms. Our findings indicated that under the periodontitis microenvironment, the intervention of quercetin could restore the osteo-/angiogenic capacity of periodontal ligament stem cells (PDLSCs), induce immune regulation of macrophages and exert an osteoimmunomodulatory effect. Furthermore, we also found that the above osteoimmunomodulatory effects of quercetin via macrophages could be partially blocked by the overexpression of a key microRNA--miR-21a-5p, which worked through inhibiting the expression of PDCD4 and activating the NF-κB signaling pathway. CONCLUSION: In summary, our study shows that quercetin-loaded mesoporous nano-delivery system has the potential to be a therapeutic approach for reconstructing alveolar bone defects in periodontitis. Furthermore, it also offers a new perspective for treating alveolar bone defects in periodontitis by inhibiting the expression of miR-21a-5p in macrophages and thereby creating a favorable osteoimmune microenvironment.

Bioactive materials from berberine-treated human bone marrow mesenchymal stem cells promote alveolar bone regeneration by regulating macrophage polarization.

Alveolar bone regeneration has been strongly linked to macrophage polarization. M1 macrophages aggravate alveolar bone loss, whereas M2 macrophages reverse this process. Berberine (BBR), a natural alkaloid isolated and refined from Chinese medicinal plants, has shown therapeutic effects in treating metabolic disorders. In this study, we first discovered that culture supernatant (CS) collected from BBR-treated human bone marrow mesenchymal stem cells (HBMSCs) ameliorated periodontal alveolar bone loss. CS from the BBR-treated HBMSCs contained bioactive materials that suppressed the M1 polarization and induced the M2 polarization of macrophages in vivo and in vitro. To clarify the underlying mechanism, the bioactive materials were applied to different animal models. We discovered macrophage colony-stimulating factor (M-CSF), which regulates macrophage polarization and promotes bone formation, a key macromolecule in the CS. Injection of pure M-CSF attenuated experimental periodontal alveolar bone loss in rats. Colony-stimulating factor 1 receptor (CSF1R) inhibitor or anti-human M-CSF (M-CSF neutralizing antibody, Nab) abolished the therapeutic effects of the CS of BBR-treated HBMSCs. Moreover, AKT phosphorylation in macrophages was activated by the CS, and the AKT activator reversed the negative effect of the CSF1R inhibitor or Nab. These results suggest that the CS of BBR-treated HBMSCs modulates macrophage polarization via the M-CSF/AKT axis. Further studies also showed that CS of BBR-treated HBMSCs accelerated bone formation and M2 polarization in rat teeth extraction sockets. Overall, our findings established an essential role of BBR-treated HBMSCs CS and this might be the first report to show that the products of BBR-treated HBMSCs have active effects on alveolar bone regeneration.

Biodegradable Nanoflowers with Abaloparatide Spatiotemporal Management of Functional Alveolar Bone Regeneration.

Post-extraction alveolar bone atrophy greatly hinders the subsequent orthodontic tooth movement (OTM) or implant placement. In this study, we synthesized biodegradable bifunctional bioactive calcium phosphorus nanoflowers (NFs) loaded with abaloparatide (ABL), namely ABL@NFs, to achieve spatiotemporal management for alveolar bone regeneration. The NFs exhibited a porous hierarchical structure, high drug encapsulation efficacy, and desirable biocompatibility. ABL was initially released to recruit stem cells, followed by sustained release of Ca2+ and PO43- for in situ interface mineralization, establishing an osteogenic "biomineralized environment". ABL@NFs successfully restored morphologically and functionally active alveolar bone without affecting OTM. In conclusion, the ABL@NFs demonstrated promising outcomes for bone regeneration under orthodontic condition, which might provide a desirable reference of man-made "bone powder" in the hard tissue regeneration field.

Shape memory and hemostatic silk-laponite scaffold for alveolar bone regeneration after tooth extraction trauma.

Persistent bleeding and the absence of alveolar bone stress following tooth loss can hinder socket healing, complicating future dental implant procedures, and potentially leading to neighboring tooth instability. Therefore, developing materials that promote alveolar bone regeneration and possess both hemostatic and osteogenic properties is crucial for preserving the extraction sites. This study introduces a silk-based laponite composite scaffold material with proficient hemostatic and osteogenic functions, and excellent shape-memory properties for efficient extraction- site filling. In vitro studies research demonstrated that the scaffold's inherent negative charge of the scaffold significantly enhanced blood coagulation and thrombin generation. Moreover, its porous structure and slightly rough inner surface promoted blood cell adhesion and, improved the hemostatic performance. Furthermore, the scaffold facilitated stem cell osteogenic differentiation by activating the TRPM7 channel through the released of magnesium ions. In vivo tests using rat models confirmed its effectiveness in promoting coagulation and mandibular regeneration. Thus, this study proposes a promising approach for post-extraction alveolar bone regenerative repair. The composite scaffold material, with its hemostatic and osteogenic capabilities and shape-memory features, can potentially enhance dental implant success and overall oral health.

Expression of Stro-1, Runx-2, Osterix, and Alp in Alveolar Bone Regeneration Process Following the Administration of Hydroxyapatite Gypsum Puger (HAGP) Scaffold

@#Introduction: Tooth extraction before denture placement could result in trauma and damage to up to 50% of the alveolar bone, inducing bone resorption, and affecting the patient’s quality of life. Hydroxyapatite Gypsum Puger (HAGP) can be used as an alternative to bone graft material which degrades slowly, affecting the proliferation and activity of cells that are responsible for bone tissue engineering. This study aimed to analyze the regeneration mechanism of alveolar bone by administering the HAGP scaffold and observing the Stro-1, Runx-2, Osterix, and ALP expression. Methods: Laboratory experimental research was conducted and we used 150-355µm HAGP scaffold particles, applied in vivo inside alveolar sockets of the rats for 7, 14, and 28 days, followed by immunohistochemical examination of Stro-1, Runx-2, Osterix, and ALP expressions. Results: The HAGP scaffold group showed that the Stro-1 expression was significantly higher than the K(-) group, and the Runx-2 expression increased on day 7 and decreased on day 28 in the HAGP and K(-) groups. Osterix expression increased from day 7, 14, to day 28. The high expression of Osterix on day 28 means it took over the Runx-2 function. In ALP there was a significant increase on day 7. ALP expression was a sign of early osteoblast differentiation and production by cells, this extracellular matrix mineralization is an indicator of the osteogenic process. Conclusion: Alveolar bone regeneration mechanism in rats revealed that the expression of Stro-1, Runx-2, Osterix, and ALP was higher in the HAGP scaffold group compared to the control group on days 7,14, and 28.

Research progress on cell sheet technology and its application in periodontal tissue regeneration / 口腔疾病防治

@#At present, conventional periodontal treatment cannot achieve complete and effective periodontal tissue regeneration. Cell sheet technology (CST) is a kind of cell transplantation method without scaffold material that can maintain complete extracellular matrix, important ion channels of cells, growth factor receptors, etc., and ensure the interaction between cells and the extracellular matrix. In this paper, the application and research progress of the cell sheet in the field of periodontal tissue regeneration are reviewed. Different types of seed cells can be prepared into monolayer cell sheet, multilayer cell sheet, cell sheet fragments and cell sheet polymers. Among them, the monalayer cell sheet is easily damaged and requires high deoperator; the multilayer cell sheet shows improved mechanical properties, but its thickness needs to be controlled to avoid cell necrosis. The cell sheet fragment can be used in the narrow space between the alveolar bone and root cementum to reduce the difficulty of operation and improve the mechanical properties of the cell sheet. Cell sheet polymers are three-dimensional structures that can provide strong mechanical support and improve the stability of the cell sheet, but the stability of their biological activity needs to be further improved. In methods for construction of the cell sheet, the antifibrosis and antiangiogenesis properties of the amniotic sheet have shown that this structure is suitable as the matrix of cell culture; the method of using a temperature-sensitive culture dish is simple and easy; continuous induction with vitamin C can retain some important proteins on the cell surface; and the magnetic tissue engineering method can increase cell adhesion and easily form a stable cell sheet. The above methods have their own characteristics. In clinical applications, monolayer cell sheet is mainly used for direct transplantation to the receiving site to construct periodontal tissue; multilayer cell sheet of the same or different species overlap and are then transplanted to the receiving site; and multilayer cell sheet of the same kind are wrapped with scaffold material and then transplanted to the receiving site to construct a three-dimensional structure. Overall, cell sheet technology has shown good potential in periodontal tissue regeneration.

Randomized clinical trial on the efficacy of Escherichia coli-derived rhBMP-2 with beta-TCP/HA in extraction socket

PURPOSE: This randomized clinical trial was conducted to assess the safety and effectiveness of the ErhBMP-2 in alveolar bone regeneration as well as preservation of the beta-TCP bone graft material that contains ErhBMP-2. MATERIALS AND METHODS: This study involved 72 patients at the 3 study centers. The patients, who were divided into 2 groups: the experiment group who had ErhBMP-2 coated TCP/HA and the control group who had TCP/HA graft material alone transplanted immediately after tooth extraction. CT was taken before and 3 months after the transplantation and healing status was compared between the two groups. The efficacy endpoints that were used to measure the degree of bone induction included alveolar bone height and 3 measurements of bone width. The paired t test was used to determine the significance of the changes (P<.05). RESULTS: Changes in alveolar bone height were -1.087 +/- 1.413 mm in the control group and -.059 +/- 0.960 mm in the experimental group (P<.01). At 25% extraction socket length [ESL], the changes were 0.006 +/- 1.149 mm in the control group and 1.279 +/- 1.387 mm in the experimental group. At 50% ESL, the changes were 0.542 +/- 1.157 mm and 1.239 +/- 1.249 mm, respectively (P<.01 for 25% ESL, and P<.05 for 50% ESL). During the experiment, no adverse reactions to the graft material were observed. CONCLUSION: ErhBMP-2 coated beta-TCP/HA were found to be more effective in preserving alveolar bone than conventional beta-TCP/HA alloplastic bone graft materials.

Clinical evaluation of alveolar distraction osteogenesis for implant installation