Improved BMP2-CPC-stimulated osteogenesis in vitro and in vivo via modulation of macrophage polarization

Zeolite firmly anchored regenerated cellulose aerogel for efficient and biosafe hemostasis

Zeolite-based hemostats are commercially available but are still troubled by the adverse effects of exothermic heat-caused tissue damage and detached zeolite-induced distal thrombosis. Here, we developed a facile and robust method to fabricate zeolite-embedded regenerated cellulose aerogel (Z-RCA) for safe and efficient hemostasis. Zeolite particles were extensively entangled by regenerated cellulose nanofibers via hydrogen bonds during the cellulose regeneration process, thus reducing the probability of zeolite detaching from aerogel. Additionally, the low loading ratio of zeolite (∼3.0 wt%) decreased the exothermic heat to promote a low-temperature enhancement of 3.4 °C during the hemostatic process. The aerogel quickly absorbed tremendous blood while releasing calcium ions, synergistically assisting zeolite to promote blood coagulation. In animal experiments, Z-RCA stopped bleeding faster than Quikclot and reduced blood loss by 62.1 wt%. Overall, the study produced a safe and efficient zeolite-based hemostat.

Growth factor-functionalized titanium implants for enhanced bone regeneration: A review

Titanium and titanium alloys are widely favored materials for orthopedic implants due to their exceptional mechanical properties and biological inertness. The additional benefit of sustained local release of bioactive substances further promotes bone tissue formation, thereby augmenting the osseointegration capacity of titanium implants and attracting increasing attention in bone tissue engineering. Among these bioactive substances, growth factors have shown remarkable osteogenic and angiogenic induction capabilities. Consequently, researchers have developed various physical, chemical, and biological loading techniques to incorporate growth factors into titanium implants, ensuring controlled release kinetics. In contrast to conventional treatment modalities, the localized release of growth factors from functionalized titanium implants not only enhances osseointegration but also reduces the risk of complications. This review provides a comprehensive examination of the types and mechanisms of growth factors, along with a detailed exploration of the methodologies used to load growth factors onto the surface of titanium implants. Moreover, it highlights recent advancements in the application of growth factors to the surface of titanium implants (Scheme 1). Finally, the review discusses current limitations and future prospects for growth factor-functionalized titanium implants. In summary, this paper presents cutting-edge design strategies aimed at enhancing the bone regenerative capacity of growth factor-functionalized titanium implants-a significant advancement in the field of enhanced bone regeneration.

Naringin-induced M2 macrophage polarization facilitates osteogenesis of BMSCs and improves cranial bone defect healing in rat

Osteoimmunology has uncovered the critical role of the immune microenvironment in the bone healing process, with macrophages playing a central part in generating immune responses via chemokine production. Naringin, a flavanone glycoside extracted from various plants, has been shown to promote osteoblast differentiation, thereby enhancing bone formation and mitigating osteoporosis progression. Current research on the osteogenic mechanism primarily focuses on the direct impact of naringin on mesenchymal stem cells, while its indirect immunoregulatory effects remain elusive. In this study, we investigated the bone defect-enhancing effects of varying naringin concentrations in vivo using a cranial bone defect model in Sprague-Dawley rats. We assessed the osteoimmune modulation capacity of naringin by exposing lipopolysaccharide (LPS)-induced RAW 264.7 macrophages to different doses of naringin. To further elucidate the underlying osteogenic enhancement mechanism, Bone Marrow Stromal Cells (BMSCs) derived from mice were treated with conditioned media from naringin-treated macrophages. Our findings indicated that naringin promotes M2 phenotype polarization in macrophages, as evidenced by the downregulation of pro-inflammatory cytokines Inducible Nitric Oxide Synthase (iNOS), interleukin (IL)-1β, and Tumor Necrosis Factor (TNF)-α, and the upregulation of anti-inflammatory cytokine Transforming growth factor (TGF)-β. Transcriptome analysis revealed that differentially expressed genes were significantly enriched in osteoblast differentiation and anti-inflammatory response pathways in naringin-pretreated macrophages, with the cytokines signaling pathway being upregulated. The conditioned media from naringin-treated macrophages stimulated the expression of osteogenic-related genes Alkaline phosphatase (Alp), osteocalcin (Ocn), osteopontin (Opn), and Runt-related transcription factor (Runx) 2, as well as protein expression in BMSCs. In conclusion, naringin alleviates macrophage inflammation by promoting M2 phenotype polarization, which in turn enhances the osteogenic differentiation of BMSCs, contributing to its bone healing effects in vivo. These results suggest that naringin holds significant potential for improving bone defect healing through osteoimmune modulation.

Tendon stem cells seeded on dynamic chondroitin sulfate and chitosan hydrogel scaffold with BMP2 enhance tendon-to-bone healing

Failure to adequately reconstruct the tendon-to-bone interface constitutes the primary etiology underlying rotator cuff retear after surgery. The purpose of this study is to construct a dynamic chondroitin sulfate and chitosan hydrogel scaffold (CHS) with bone morphogenetic protein 2 (BMP2), then seed tendon stem cells (TSCs) on BMP2-CHS for the rotator cuff reconstruction of tendon-to-bone interface. In this dynamic hydrogel system, the scaffold could not only have good biocompatibility and degradability but also significantly promote the proliferation and differentiation of TSCs. The ability of BMP2-CHS combined with TSCs to promote regeneration of tendon-to-bone interface was further verified in the rabbit rotator cuff tear model. The results showed that BMP2-CHS combined with TSCs could induce considerable collagen, fibrocartilage, and bone arrangement and growth at the tendon-to-bone interface and promote the biomechanical properties. Overall, TSCs seeded on CHS with BMP2 can enhance tendon-to-bone healing and provide a new possibility for improving the poor prognosis of rotator cuff surgery.

A meta-analysis of alveolar bone grafting using bone substitutes in cleft lip and palate patients

In individuals with cleft lip and palate (CLP), an alveolar bone graft (ABG) is carried out for alveolar cleft closure. Several sources for ABG include autologous bone, xenologous bone, and alloplastic substitutes. Autologous bone has been the preferred source for ABG. Alloplastic substitutes might serve as an alternative. This study aimed to compare the outcomes between autologous and alloplastic as sources for ABG. This study made use of eight web databases. Randomized control trials (RCTs) and non-RCTs were included. CLP patients with alveolar cleft with imaging studies, computed tomography (CT scan) and/or cone beam CT scan, and bone graft volume within 6-12 months postintervention were selected. Bone graft volume within 6-12 months postintervention was assessed. Three studies met the inclusion criteria. After 6-12 months of follow-up, there were no statistically significant differences in bone graft volume between autologous and alloplastic bone grafts (fixed-effect model estimate value = 0.21; confidence interval - 0.301-0.730; P = 0.414). The limitations include small research sample sizes, a high likelihood of bias among included studies, and different alloplastic materials from each included study. Autologous and alloplastic bone grafts showed similar effectiveness in alveolar bone grafting. Further clinical trial studies with bigger sample sizes and similar interventions are needed as evidence for future reviews.

Antisense yycF and BMP-2 co-delivery gelatin methacryloyl and carboxymethyl chitosan hydrogel composite for infective bone defects regeneration

Repairing infected bone defects remains a challenge in clinical work. Intractable bacterial infections and insufficient osseointegration are major concerns for infected bone defects. To address these issues, we developed a gelatin methacryloyl (GelMA) and carboxymethyl chitosan (CMCS) composite hydrogel with BMP-2 growth factor and GO based antisense technology supported by a PLGA spring. In vitro, photo-crosslinked GelMA composite hydrogels shown excellent biocompatibility and degradability. Relying on the release of BMP-2 from the composite hydrogel provides osteogenic effects. The antisense yycF and BMP-2 were released with the degradation of GelMA and CMCS composite hydrogel. In terms of antimicrobial properties, CMCS, GO and post-transcriptional regulatory antisense yycF from the composite hydrogel synergistically kill S. aureus. In vivo, we implanted the composite hydrogel in a rat model of S. aureus infected femur defect, effectively accelerating bone healing in an infectious microenvironment. This research provides a novel biomaterial that is both antimicrobial and promotes bone regeneration, with the potential to treat infected bone defects.

Hippo-YAP/TAZ signaling in osteogenesis and macrophage polarization: Therapeutic implications in bone defect repair

Bone defects caused by diseases or surgery are a common clinical problem. Researchers are devoted to finding biological mechanisms that accelerate bone defect repair, which is a complex and continuous process controlled by many factors. As members of transcriptional costimulatory molecules, Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) play an important regulatory role in osteogenesis, and they affect cell function by regulating the expression of osteogenic genes in osteogenesis-related cells. Macrophages are an important group of cells whose function is regulated by YAP/TAZ. Currently, the relationship between YAP/TAZ and macrophage polarization has attracted increasing attention. In bone tissue, YAP/TAZ can realize diverse osteogenic regulation by mediating macrophage polarization. Macrophages polarize into M1 and M2 phenotypes under different stimuli. M1 macrophages dominate the inflammatory response by releasing a number of inflammatory mediators in the early phase of bone defect repair, while massive aggregation of M2 macrophages is beneficial for inflammation resolution and tissue repair, as they secrete many anti-inflammatory and osteogenesis-related cytokines. The mechanism of YAP/TAZ-mediated macrophage polarization during osteogenesis warrants further study and it is likely to be a promising strategy for bone defect repair. In this article, we review the effect of Hippo-YAP/TAZ signaling and macrophage polarization on bone defect repair, and highlight the regulation of macrophage polarization by YAP/TAZ.

State-of-the-art polyetheretherketone three-dimensional printing and multifunctional modification for dental implants

Polyetheretherketone (PEEK) is a high-performance thermoplastic polymer with an elastic modulus close to that of the jawbone. PEEK has the potential to become a new dental implant material for special patients due to its radiolucency, chemical stability, color similarity to teeth, and low allergy rate. However, the aromatic main chain and lack of surface charge and chemical functional groups make PEEK hydrophobic and biologically inert, which hinders subsequent protein adsorption and osteoblast adhesion and differentiation. This will be detrimental to the deposition and mineralization of apatite on the surface of PEEK and limit its clinical application. Researchers have explored different modification methods to effectively improve the biomechanical, antibacterial, immunomodulatory, angiogenic, antioxidative, osteogenic and anti-osteoclastogenic, and soft tissue adhesion properties. This review comprehensively summarizes the latest research progress in material property advantages, three-dimensional printing synthesis, and functional modification of PEEK in the fields of implant dentistry and provides solutions for existing difficulties. We confirm the broad prospects of PEEK as a dental implant material to promote the clinical conversion of PEEK-based dental implants.

Research progress of odontogenic extracellular vesicles in regeneration of dental pulp

It is well understood that maintaining viable pulp is critical for tooth retention. This review focused on cell-free therapy based on extracellular vesicles (EVs), a novel minimally invasive treatment strategy for endodontic restoration. This study was conducted by searching mainstream electronic databases such as Web of Science and PubMed for relevant studies on the therapeutic role of odontogenic EVs in pulp healing published in the last five years. We selected 89 relevant articles and discovered that dental stem cells (DSCs) derived EVs (DSC-EVs) have become a research hotspot in oral regenerative medicine, with significant advantages over cell transplantation in terms of low immunogenicity, ease of isolation, preservation, and management. Here, we introduce in detail the therapeutic effects of DSC-EVs for pulp restoration from three perspectives: excellent odontogenic properties, clinical applications, and possible molecular mechanisms. This article contributes a new viewpoint to the field of regenerative endodontics.

A new osteogenic protein isolated from Dioscorea opposita Thunb accelerates bone defect healing through the mTOR signaling axis

Delayed bone defect repairs lead to severe health and socioeconomic impacts on patients. Hence, there are increasing demands for medical interventions to promote bone defect healing. Recombinant proteins such as BMP-2 have been recognized as one of the powerful osteogenic substances that promote mesenchymal stem cells (MSCs) to osteoblast differentiation and are widely applied clinically for bone defect repairs. However, recent reports show that BMP-2 treatment has been associated with clinical adverse side effects such as ectopic bone formation, osteolysis and stimulation of inflammation. Here, we have identified one new osteogenic protein, named 'HKUOT-S2' protein, from Dioscorea opposita Thunb. Using the bone defect model, we have shown that the HKUOT-S2 protein can accelerate bone defect repair by activating the mTOR signaling axis of MSCs-derived osteoblasts and increasing osteoblastic biomineralization. The HKUOT-S2 protein can also modulate the transcriptomic changes of macrophages, stem cells, and osteoblasts, thereby enhancing the crosstalk between the polarized macrophages and MSCs-osteoblast differentiation to facilitate osteogenesis. Furthermore, this protein had no toxic effects in vivo. We have also identified HKUOT-S2 peptide sequence TKSSLPGQTK as a functional osteogenic unit that can promote osteoblast differentiation in vitro. The HKUOT-S2 protein with robust osteogenic activity could be a potential alternative osteoanabolic agent for promoting osteogenesis and bone defect repairs. We believe that the HKUOT-S2 protein may potentially be applied clinically as a new class of osteogenic agent for bone defect healing.

CaP-coated Zn-Mn-Li alloys regulate osseointegration via influencing macrophage polarization in the osteogenic environment

Immune response is an important factor in determining the fate of bone replacement materials, in which macrophages play an important role. It is a new idea to design biomaterials with immunomodulatory function to reduce inflammation and promote bone integration by regulating macrophages polarization. In this work, the immunomodulatory properties of CaP Zn-Mn-Li alloys and the specific mechanism of action were investigated. We found that the CaP Zn0.8Mn0.1Li alloy promoted the polarization of macrophages toward M2 and reduced inflammation, which could effectively upregulate osteogenesis-related factors and promote new bone formation, indicating the important role of macrophages polarization in biomaterial induction of osteogenesis. In vivo studies further demonstrated that CaP Zn0.8Mn0.1Li alloy could stimulate osteogenesis better than other Zn-Mn-Li alloys implantations by regulating macrophages polarization and reducing inflammation. In addition, transcriptome results showed that CaP Zn0.8Mn0.1Li played an important regulatory role in the life process of macrophages, activating Toll-like receptor signaling pathway, which participated in the activation and attenuation of inflammation, and accelerated bone integration. Thus, by preparing CaP coatings on the surface of Zn-Mn-Li alloys and combining the bioactive ingredient with controlled release, the biomaterial will be imbibed with beneficial immunomodulatory properties that promote bone integration.

Regulating macrophage-MSC interaction to optimize BMP-2-induced osteogenesis in the local microenvironment

Bone morphogenetic protein (BMP-2) has been approved by the FDA to promote bone regeneration, but uncertain osteogenic effect and dose-dependent side effects may occur. Osteoimmunomodulation plays an important role in growth factor-based osteogenesis. Here, we explored how proinflammatory signals affect the dose-dependent osteogenic potential of BMP-2. We observed that the expression level of local IL-1β did not increase with the dose of BMP-2 in the mouse osteogenesis model. A low dose of BMP-2 could not promote new bone formation, but trigger the release of IL-1β from M1 macrophages. As the dose of BMP-2 increased, the IL-1β expression and M1 infiltration in local microenvironment were inhibited by IL-1Ra from MSCs under osteogenic differentiation induced by BMP-2, and new bone tissues formed, even excessively. Anti-inflammatory drugs (Dexamethasone, Dex) promoted osteogenesis via inhibiting M1 polarization and enhancing BMP-2-induced MSC osteo-differentiation. Thus, we suggest that the osteogenic effect of BMP-2 involves macrophage-MSC interaction that is dependent on BMP-2 dose and based on IL-1R1 ligands, including IL-1β and IL-1Ra. The dose of BMP-2 could be reduced by introducing immunoregulatory strategies.

Nanowhiskers Orchestrate Bone Formation and Bone Defect Repair by Modulating Immune Cell Behavior

Immunomodulatory biomaterials have emerged as promising treatment agents for bone defects. However, it is unclear how such biomaterials control immune cell behaviors to facilitate large-segment bone defect repair. Herein, we fabricated biphasic calcium phosphate ceramics with nanowhisker structures to explore the immunoregulation features and influence on large-segment bone defect repair. We found that the nanowhisker structures markedly facilitated large-segment bone defect repair by promoting bone regeneration and scaffold resorption. Our in vitro experiment and transcriptomic analysis showed that mechanical stress derived from nanowhisker structures may activate the transcription of Egr-1 to induce early switch of macrophage phenotype to M2, which could not only facilitate osteogenic differentiation of BMSCs but also enhance the expression of osteoclast differentiation-regulating genes of M2 macrophage. In vivo study showed that the nanowhisker structures relieved local inflammatory responses by inducing early switch of macrophage phenotype from M1 to M2, which resulted in accelerated osteoclastogenesis for biomaterial resorption and osteogenesis for ectopic bone formation. Hence, we presume that nanowhisker structures may orchestrate bone formation and material resorption coupling to facilitate large-segment bone defect repair by controlling the switch of macrophage phenotype. This study provides new insight into the designing of immunomodulatory tissue engineering biomaterials for treating large-segment bone defects.

Sequential gastrodin release PU/n-HA composite scaffolds reprogram macrophages for improved osteogenesis and angiogenesis

Wound healing is a highly orchestrated process involving a variety of cells, including immune cells. Developing immunomodulatory biomaterials for regenerative engineering applications, such as bone regeneration, is an appealing strategy. Herein, inspired by the immunomodulatory effects of gastrodin (a bioactive component in traditional Chinese herbal medicine), a series of new immunomodulatory gastrodin-comprising biodegradable polyurethane (gastrodin-PU) and nano-hydroxyapatite (n-HA) (gastrodin-PU/n-HA) composites were developed. RAW 264.7 macrophages, rat bone marrow mesenchymal stem cells (rBMSCs), and human umbilical vein endothelial cells (HUVECs) were cultured with gastrodin-PU/n-HA containing different concentrations of gastrodin (0.5%, 1%, and 2%) to decipher their immunomodulatory effects on osteogenesis and angiogenesis in vitro. Results demonstrated that, compared with PU/n-HA, gastrodin-PU/n-HA induced macrophage polarization toward the M2 phenotype, as evidenced by the higher expression level of pro-regenerative cytokines (CD206, Arg-1) and the lower expression of pro-inflammatory cytokines (iNOS). The expression levels of osteogenesis-related factors (BMP-2 and ALP) in the rBMSCs and angiogenesis-related factors (VEGF and BFGF) in the HUVECs were significantly up-regulated in gastrodin-PU/n-HA/macrophage-conditioned medium. The immunomodulatory effects of gastrodin-PU/n-HA to reprogram macrophages from a pro-inflammatory (M1) phenotype to an anti-inflammatory and pro-healing (M2) phenotype were validated in a rat subcutaneous implantation model. And the 2% gastrodin-PU/n-HA significantly decreased fibrous capsule formation and enhanced angiogenesis. Additionally, 2% gastrodin-PU/n-HA scaffolds implanted in the rat femoral condyle defect model showed accelerated osteogenesis and angiogenesis. Thus, the novel gastrodin-PU/n-HA scaffold may represent a new and promising immunomodulatory biomaterial for bone repair and regeneration.

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A new immunomodulatory gastrodin-PU/n-HA biomaterial has been developed.

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The gastrodin-PU/n-HA triggered M2 macrophage polarization.

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The osteogenesis and angiogenesis were enhanced in response to the local immune microenvironment.

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The findings prove a therapeutic strategy in bone defect and other inflammatory osteoimmune disorders.

Osteoclast-Driven Osteogenesis, Bone Remodeling and Biomaterial Resorption: A New Profile of BMP2-CPC-Induced Alveolar Bone Regeneration

This bedside-to-bench study aimed to systematically investigate the value of applying BMP2-loaded calcium phosphate cement (BMP2-CPC) in the restoration of large-scale alveolar bone defects. Compared to deproteinized bovine bone (DBB), BMP2-CPC was shown to be capable of inducing a favorable pattern of bone regeneration and bone remodeling accompanied by active osteoclastogenesis and optimized biomaterial resorption when applied in reconstructive periodontally accelerated osteogenic orthodontics (PAOO) surgery. To verify the regulatory role of osteoclasts in the BMP2-CPC-induced pattern of bone regeneration, in vitro and in vivo studies were designed to elucidate the underlying mechanism. Our results revealed that osteoclasts played a multifaceted role (facilitating osteogenesis, bone remodeling and biomaterial resorption) in the BMP2-CPC-induced bone regeneration. Osteoclasts contributed to the osteogenic differentiation of mesenchymal stem cells (MSCs) by secreting calcium ions, CTHRC1 and PDGF-B. Moreover, the increased osteoclasts promoted the remodeling of new bone and BMP2-CPC resorption, leading to a harmonized replacement of biomaterials with mature bone. In conclusion, the in vitro and in vivo experimental results corresponded with the clinical results and showed the optimized properties of BMP2-CPC in activating osteoclast-driven bone regeneration and remodeling, thus indicating the highly promising prospects of BMP2-CPC as an ideal therapeutic for alveolar bone defects.

The strategy of composite grafting with BMP2-Loaded calcium phosphate cements and autogenous bone for alveolar cleft reconstruction

Purpose: To remedy the drawbacks of traditional autogenous bone harvesting in alveolar bone grafting (ABG), a novel strategy of composite grafting with BMP2-loaded calcium phosphate cements (BMP2-CPC) and autogenous bone harvested by minimally invasive technique was developed and evaluated for its bone-repairing efficacy.

Materials and methods: A chart review was conducted for 19 patients with unilateral alveolar clefts who underwent secondary ABG from 2017 to 2020. Of the enrolled patients, 9 patients underwent grafting with autogenous bone harvested by traditional trap door technique (group I), and 10 patients underwent grafting with the composite graft comprising BMP2-CPC and autogenous bone harvested by minimally invasive technique at a ratio of 1:1 by volume (group II). The clinical performance of the composite graft was comprehensively evaluated in terms of clinical, radiographic and histological perspectives.

Results: The present results demonstrated that the composite graft exhibited satisfactory bone-repairing efficacy comparable to that of the autogenous bone graft on the premise of lower amount of harvested bone. The post-surgical resorption of bone volume and vertical height of grafted area was significantly slower in group II. The favourable resorption performance of BMP2-CPC contributed to preserving the post-surgical bony contour reconstructed with the composite graft.

Conclusion: The composite graft comprising BMP2-CPC and autogenous bone harvested by minimally invasive technique was demonstrated to be an eligible alternative for application in ABG, especially for its improved resorption performance in preserving post-surgical bony contour.

Treatment methods toward improving the anti-infection ability of poly(etheretherketone) implants for medical applications

Due to its favorable chemical stability, biocompatibility, and mechanical properties, Poly(etheretherketone) (PEEK) is a promising material for repairing bone and dental hard tissue defects. However, there are critical disadvantages: PEEK is biologically and chemically inert, which influences osseointegration of implants and bonding strength of prostheses, and its mechanical properties still cannot meet the requirements for some medical applications. Furthermore, bacterial infections and inflammatory reactions often accompany bone defects caused by trauma or inflammation or teeth loss caused by periodontitis. Previous studies mainly focused on enhancing PEEK's bioactivity and mechanical performance, but PEEK also lacks effective anti-infection ability. Thus, it is necessary to improve its anti-infection ability, and this is considered in this paper from two aspects. The first is to inhibit the attachment and growth of bacteria on the material, and the second is to endow the material with immunoregulatory ability, which means mobilizing the host immune system to protect tissue from inflammation. In this review, we analyze and discuss the existing treatment methods to improve the antibacterial and immunomodulatory abilities of PEEK addressing their limitations, relevant future challenges, and required research efforts.

Immunomodulation Effect of Biomaterials on Bone Formation

Traditional bone replacement materials have been developed with the goal of directing the osteogenesis of osteoblastic cell lines toward differentiation and therefore achieving biomaterial-mediated osteogenesis, but the osteogenic effect has been disappointing. With advances in bone biology, it has been revealed that the local immune microenvironment has an important role in regulating the bone formation process. According to the bone immunology hypothesis, the immune system and the skeletal system are inextricably linked, with many cytokines and regulatory factors in common, and immune cells play an essential role in bone-related physiopathological processes. This review combines advances in bone immunology with biomaterial immunomodulatory properties to provide an overview of biomaterials-mediated immune responses to regulate bone regeneration, as well as methods to assess the bone immunomodulatory properties of bone biomaterials and how these strategies can be used for future bone tissue engineering applications.

Extracellular vesicles from the inflammatory microenvironment regulate the osteogenic and odontogenic differentiation of periodontal ligament stem cells by miR-758-5p/LMBR1/BMP2/4 axis

Background

Extracellular vesicles (EVs) play a key role in constructing a microenvironment that favors the differentiation of stem cells. The present work aimed to determine the molecular mechanisms by which EV derived from inflammatory dental pulp stem cell (iDPSC-EV) influence periodontal ligament stem cells (PDLSCs) and provide a potential strategy for bone and dental pulp regeneration.

Methods

The osteogenic and odontogenic differentiation was assessed by quantitative real-time polymerase chain reaction (qRT-PCR), western blot, alkaline phosphatase (ALP) activity assay, ALP staining, alizarin red S (ARS) staining, and immunofluorescence staining. To detect proliferation, the Cell Counting Kit-8 (CCK-8) assay, and flow cytometry analysis were used. EVs were isolated by the Exoperfect kit and ultrafiltration and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and western blot. The expression profile of miRNAs in EVs was studied using miRNA sequence and bioinformatics, and one of the upregulated miRNAs was evaluated on PDLSCs.

Results

The inflammatory microenvironment stimulated osteogenic and odontogenic differentiation of DPSCs and iDPSC-EV behaved alike on PDLSCs. MiR-758-5p was upregulated in iDPSC-EV and was demonstrated to play a significant role in the osteogenic and odontogenic commitment of PDLSCs. A dual-luciferase reporter assay confirmed the binding site between miR-758-5p and limb development membrane protein 1 (LMBR1). The knockdown of LMBR1 also enhanced the above potential. Mechanically, bone morphogenetic protein (BMP) signaling was activated.

Conclusions

EVs from the inflammatory microenvironment enhanced the osteogenic and odontogenic differentiation of PDLSCs partly by shuttering LMBR1-targeting miR-758-5p via BMP signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03412-9.

Titanium alloy composited with dual-cytokine releasing polysaccharide hydrogel to enhance osseointegration via osteogenic and macrophage polarization signaling pathways

Titanium alloy has been widely used in orthopedic surgeries as bone defect filling. However, the regeneration of high-quality new bones is limited due to the pro-inflammatory microenvironment around implants, resulting in a high occurrence rate of implant loosening or failure in osteological therapy. In this study, extracellular matrix (ECM)-mimetic polysaccharide hydrogel co-delivering BMP-2 and IL-4 was composited with 3D printed titanium alloy to promote the osseointegration and regulate macrophage response to create a pro-healing microenvironment in bone defect. Notably, it is discovered from the bioinformatics data that IL-4 and BMP-2 could affect each other through multiple signal pathways to achieve a synergistic effect towards osteogenesis. The composite scaffold significantly promoted the osteoblast differentiation and proliferation of human bone marrow mesenchyme stem cells (hBMSCs). The repair of large-scale femur defect in rat indicated that the dual-cytokine-delivered composite scaffold could manipulate a lower inflammatory level in situ by polarizing macrophages to M2 phenotype, resulting in superior efficacy of mature new bone regeneration over the treatment of native titanium alloy or that with an individual cytokine. Collectively, this work highlights the importance of M2-type macrophages-enriched immune-environment in bone healing. The biomimetic hydrogel-metal implant composite is a versatile and advanced scaffold for accelerating in vivo bone regeneration, holding great promise in treating orthopedic diseases.

Bio-clickable mussel-inspired peptides improve titanium-based material osseointegration synergistically with immunopolarization-regulation

Upon the osteoporotic condition, sluggish osteogenesis, excessive bone resorption, and chronic inflammation make the osseointegration of bioinert titanium (Ti) implants with surrounding bone tissues difficult, often lead to prosthesis loosening, bone collapse, and implant failure. In this study, we firstly designed clickable mussel-inspired peptides (DOPA-N3) and grafted them onto the surfaces of Ti materials through robust catechol-TiO₂ coordinative interactions. Then, two dibenzylcyclooctyne (DBCO)-capped bioactive peptides RGD and BMP-2 bioactive domain (BMP-2) were clicked onto the DOPA-N3-coated Ti material surfaces via bio-orthogonal reaction. We characterized the surface morphology and biocompatibility of the Ti substrates and optimized the osteogenic capacity of Ti surfaces through adjusting the ideal ratios of BMP-2/RGD at 3:1. In vitro, the dual-functionalized Ti substrates exhibited excellent promotion on adhesion and osteogenesis of mesenchymal stem cells (MSCs), and conspicuous immunopolarization-regulation to shift macrophages to alternative (M2) phenotypes and inhibit inflammation, as well as enhancement of osseointegration and mechanical stability in osteoporotic rats. In summary, our biomimetic surface modification strategy by bio-orthogonal reaction provided a convenient and feasible method to resolve the bioinertia and clinical complications of Ti-based implants, which was conducive to the long-term success of Ti implants, especially in the osteoporotic or inflammatory conditions.

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A clickable mussel-inspired peptide and two DBCO-capped bioactive peptides for facile decoration of Ti prostheses via robust catechol/TiO2 coordinative interactions and click chemical reaction.

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Dual functionalized Ti-based surface can improve cell anchoring and osteogenicitity by rationally adjusting the grafting ratio of BMP-2 and RGD peptides.

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Dual functionalized Ti-based surface synergistically achieve M2 shifting and efficient inflammation inhibition for osseointegration.

Effective Actions of Ion Release from Mesoporous Bioactive Glass and Macrophage Mediators on the Differentiation of Osteoprogenitor and Endothelial Progenitor Cells

Due to their specific mesoporous structure and large surface area, mesoporous bioactive glasses (MBGs) possess both drug-delivery ability and effective ionic release to promote bone regeneration by stimulating osteogenesis and angiogenesis. Macrophages secrete mediators that can affect both processes, depending on their phenotype. In this work, the action of ion release from MBG-75S, with a molar composition of 75SiO2-20CaO-5P2O5, on osteogenesis and angiogenesis and the modulatory role of macrophages have been assessed in vitro with MC3T3-E1 pre-osteoblasts and endothelial progenitor cells (EPCs) in monoculture and in coculture with RAW 264.7 macrophages. Ca2+, phosphorous, and silicon ions released from MBG-75S were measured in the culture medium during both differentiation processes. Alkaline phosphatase activity and matrix mineralization were quantified as the key markers of osteogenic differentiation in MC3T3-E1 cells. The expression of CD31, CD34, VEGFR2, eNOS, and vWF was evaluated to characterize the EPC differentiation into mature endothelial cells. Other cellular parameters analyzed included the cell size and complexity, intracellular calcium, and intracellular content of the reactive oxygen species. The results obtained indicate that the ions released by MBG-75S promote osteogenesis and angiogenesis in vitro, evidencing a macrophage inhibitory role in these processes and demonstrating the high potential of MBG-75S for the preparation of implants for bone regeneration.