Adaptive Nanoparticle-Mediated Modulation of Mitochondrial Homeostasis and Inflammation to Enhance Infected Bone Defect Healing.

Infected bone defects (IBDs) exhibit impaired healing due to excessive inflammation triggered by pathogen-associated molecular patterns (PAMPs) from bacteria. As a vital factor in orchestrating immune responses, mitochondrial homeostasis maintenance is central to inflammation blockade. This research developed a chameleon-like nanoplatform by covering hydroxyapatite nanoparticles with a cerium ion coordinated tannic acid supramolecular network (HA@Ce-TA), which adaptively functions to regulate mitochondrial homeostasis based on intra- and extracellular environments. Extracellularly, acidic conditions activate HA@Ce-TA's peroxidase/oxidase-mimicking activity to produce reactive oxygen species (ROS), and external near-infrared (NIR) irradiation excites nanoscale Ce-TA to produce hyperthermia, which is found and explained by chemical computation. ROS production with photothermal therapy can eliminate bacteria effectively and reduce mitochondrial stress. Intracellularly, HA@Ce-TA remodels mitochondrial dynamics by upregulating mitochondrial fusion genes and eliminates excessive ROS by mimicking superoxidase/catalase. Consequently, this comprehensive modulation of mitochondrial homeostasis inhibits inflammasome overactivation. In vitro and in vivo studies showed HA@Ce-TA can modulate the mitochondria-centered inflammatory cascade to enhance IBD treatment, highlighting the potential of engineering nanotherapeutics to recalibrate mitochondrial homeostasis as an infected disease-modifying intervention.

A Dual-Antioxidative Coating on Transmucosal Component of Implant to Repair Connective Tissue Barrier for Treatment of Peri-Implantitis.

Since the microgap between implant and surrounding connective tissue creates the pass for pathogen invasion, sustained pathological stimuli can accelerate macrophage-mediated inflammation, therefore affecting peri-implant tissue regeneration and aggravate peri-implantitis. As the transmucosal component of implant, the abutment therefore needs to be biofunctionalized to repair the gingival barrier. Here, a mussel-bioinspired implant abutment coating containing tannic acid (TA), cerium and minocycline (TA-Ce-Mino) is reported. TA provides pyrogallol and catechol groups to promote cell adherence. Besides, Ce3+ /Ce4+  conversion exhibits enzyme-mimetic activity to remove reactive oxygen species while generating O2 , therefore promoting anti-inflammatory M2 macrophage polarization to help create a regenerative environment. Minocycline is involved on the TA surface to create local drug storage for responsive antibiosis. Moreover, the underlying therapeutic mechanism is revealed whereby the coating exhibits exogenous antioxidation from the inherent properties of Ce and TA and endogenous antioxidation through mitochondrial homeostasis maintenance and antioxidases promotion. In addition, it stimulates integrin to activate PI3K/Akt and RhoA/ROCK pathways to enhance VEGF-mediated angiogenesis and tissue regeneration. Combining the antibiosis and multidimensional orchestration, TA-Ce-Mino repairs soft tissue barriers and effector cell differentiation, thereby isolating the immune microenvironment from pathogen invasion. Consequently, this study provides critical insight into the design and biological mechanism of abutment surface modification to prevent peri-implantitis.

Catechol-Modified and MnO2-Nanozyme-Reinforced Hydrogel with Improved Antioxidant and Antibacterial Capacity for Periodontitis Treatment.

Periodontitis is an inflammatory disease characterized by tooth loss and alveolar bone resorption. Bacteria are the original cause of periodontitis, and excess reactive oxygen species (ROS) encourage and intensify inflammation. In this study, a mussel-inspired and MnO2 NPs-reinforced adhesive hydrogel capable of alleviating periodontitis with improved antibacterial and antioxidant abilities was developed. The hydrogel was created by combining polyvinyl alcohol (PVA), 3,4-dihydroxy-d-phenylalanine (DOPA), and MnO2 nanoparticles (NPs) (named PDMO hydrogel). The hydrogel was demonstrated to be able to scavenge various free radicals (including total ROS─O2•- and OH•) and relieve the hypoxia in an inflammatory microenvironment by scavenging excess ROS and generating O2 due to its superoxide dismutase (SOD)/catalase (CAT)-like activity. Besides, under 808 nm near-infrared (NIR) light, the photothermal performance of the PDMO hydrogel displayed favorable antibacterial and antibiofilm effects toward Escherichia coli, Staphylococcus aureus, and Porphyromonas gingivalis (up to nearly 100% antibacterial rate). Furthermore, the PDMO hydrogel exhibited favorable therapeutic efficacy in alleviating gingivitis in Sprague-Dawley rats, even comparable to or better than the commercial PERIO. In addition, in the periodontitis models, the PDMO2 group showed the height of the residual alveolar bone and the smallest shadow area of low density among other groups, indicating the positive role of the PDMO2 hydrogel in bone regeneration. Finally, the biosafety of the PDMO hydrogel was comprehensively investigated, and the hydrogel was demonstrated to have good biocompatibility. Therefore, the developed PDMO hydrogel provided an effective solution to resolve biofilm recolonization and oxidative stress in periodontitis and could be a superior candidate for local drug delivery system in the clinical management of periodontitis with great potential for future clinical translation.

Dual Photo-Enhanced Interpenetrating Network Hydrogel with Biophysical and Biochemical Signals for Infected Bone Defect Healing.

The healing of infected bone defects (IBD) is a complex physiological process involving a series of spatially and temporally overlapping events, including pathogen clearance, immunological modulation, vascularization, and osteogenesis. Based on the theory that bone healing is regulated by both biochemical and biophysical signals, in this study, a copper doped bioglass (CuBGs)/methacryloyl-modified gelatin nanoparticle (MA-GNPs)/methacrylated silk fibroin (SilMA) hybrid hydrogel is developed to promote IBD healing. This hybrid hydrogel demonstrates a dual-photocrosslinked interpenetrating network mechanism, wherein the photocrosslinked SilMA as the main network ensures structural integrity, and the photocrosslinked MA-GNPs colloidal network increases strength and dissipates loading forces. In an IBD model, the hydrogel exhibits excellent biophysical characteristics, such as adhesion, adaptation to irregular defect shapes, and in situ physical reinforcement. At the same time, by sequentially releasing bioactive ions such as Cu2+ , Ca2+ , and Si2+ ions from CuBGs on demand, the hydrogel spatiotemporally coordinates antibacterial, immunomodulatory and bone remodeling events, efficiently removing infection and accelerating bone repair without the use of antibiotics or exogenous recombinant proteins. Therefore, the hybrid hydrogel can be used as a simple and effective method for the treatment of IBD.

Portable Handheld "SkinPen" Loaded with Biomaterial Ink for In Situ Wound Healing.

In situ bioprinting has emerged as an attractive tool for directly depositing therapy ink at the defective area to adapt to the irregular wound shape. However, traditional bioprinting exhibits an obvious limitation in terms of an unsatisfactory bioadhesive effect. Here, a portable handheld bioprinter loaded with biomaterial ink is designed and named "SkinPen". Gelatin methacrylate (GelMA) and Cu-containing bioactive glass nanoparticles (Cu-BGn) serve as the main components to form the hydrogel ink, which displays excellent biocompatibility and antibacterial and angiogenic properties. More importantly, by introducing ultrasound and ultraviolet in a sequential programmed manner, the SkinPen achieves in situ instant gelation and amplified (more than threefold) bioadhesive shear strength. It is suggested that ultrasound-induced cavitation and the resulting topological entanglement contribute to the enhanced bioadhesive performance together. Combining the ultrasound-enhanced bioadhesion with the curative role of the hydrogel, the SkinPen shows a satisfactory wound-healing effect in diabetic rats. Given the detachable property of the SkinPen, the whole device can be put in a first-aid kit. Therefore, the application scenarios can be expanded to many kinds of accidents. Overall, this work presents a portable handheld SkinPen that might provide a facile but effective approach for clinical wound management.

An All-in-One "4A Hydrogel": through First-Aid Hemostatic, Antibacterial, Antioxidant, and Angiogenic to Promoting Infected Wound Healing.

Currently used wound dressings are ineffective. Hence, there is a need to develop introduce a high-performance medicament with multiple functions including rapid hemostasis and excellent antibacterial activity to meet the growing worldwide demand for wound healing products. Here, inspired by the strong adhesion of mussels and the enzyme-mimicking activity of nanometallic biomaterials, the authors developed an injectable hydrogel to overcome multiple limitations of current wound dressings. The hydrogel is synthesized via esterification reaction between poly(vinyl alcohol) (PVA) and 3,4-dihydroxyphenylalanine (DOPA), followed by catechol-metal coordination between Cu2+ and the catechol groups of DOPA to form a PVA-DOPA-Cu (PDPC) hydrogel. The PDPC hydrogel possesses excellent tissue adhesive, antioxidative, photothermal, antibacterial, and hemostatic properties. The hydrogel rapidly and efficiently stopped bleeding under different traumatic conditions, including otherwise-lethal liver injury, high-pressure carotid artery rupture, and even fatal cardiac penetration injuries in animal models. Furthermore, it is demonstrated that the PDPC hydrogel affected high-performance wound repair and tissue regeneration by accelerating re-epithelialization, promoting collagen deposition, regulating inflammation, and contributing to vascularization. The results show that PDPC hydrogel is a promising candidate for rapid hemorrhage control and efficient wound healing in multiple clinical applications.

Highly elastic and self-healing nanostructured gelatin/clay colloidal gels with osteogenic capacity for minimally invasive and customized bone regeneration.

Extrusible biomaterials have recently attracted increasing attention due to the desirable injectability and printability to allow minimally invasive administration and precise construction of tissue mimics. Specifically, self-healing colloidal gels are a novel class of candidate materials as injectables or printable inks considering their fascinating viscoelastic behavior and high degree of freedom on tailoring their compositional and mechanical properties. Herein, we developed a novel class of adaptable and osteogenic composite colloidal gels via electrostatic assembly of gelatin nanoparticles and nanoclay particles. These composite gels exhibited excellent injectability and printability, and remarkable mechanical properties reflected by the maximal elastic modulus reaching ∼150 kPa combined with high self-healing efficiency, outperforming most previously reported self-healing hydrogels. Moreover, the cytocompatibility and the osteogenic capacity of the colloidal gels were demonstrated by inductive culture of MC3T3 cells seeded on the three-dimensional (3D)-printed colloidal scaffolds. Besides, the biocompatibility and biodegradability of the colloidal gels was provedin vivoby subcutaneous implantation of the 3D-printed scaffolds. Furthermore, we investigated the therapeutic capacity of the colloidal gels, either in form of injectable gels or 3D-printed bone substitutes, using rat sinus bone augmentation model or critical-sized cranial defect model. The results confirmed that the composite gels were able to adapt to the local complexity including irregular or customized defect shapes and continuous on-site mechanical stimuli, but also to realize osteointegrity with the surrounding bone tissues and eventually be replaced by newly formed bones.

A Mechanically Reinforced Super Bone Glue Makes a Leap in Hard Tissue Strong Adhesion and Augmented Bone Regeneration.

Existing bone tissue engineering strategies aim to achieve minimize surgical trauma, stabilize the injured area, and establish a dynamic osteogenic microenvironment. The cutting-edge bone glue developed in this study satisfies these criteria. Inspired by the excellent adhesive properties of mussels, herein, a super osteogenic glue (L-DPZ) that integrates poly(vinyl alcohol), L-dopa amino acid, and zeolitic imidazolate framework-8 characterized by catechol-metal coordination is used to successfully adhere to hard tissue with a maximum adhesive strength of 10 MPa, which is much higher than those of commercial and previously reported bone glues. The stable hard tissue adhesion also enables it to adhere strongly to luxated or broken teeth, Bio-Oss (a typical bone graft material), and splice fragments from comminuted fractures of the rabbit femur. Then, it is testified that the L-DPZ hydrogels exhibit satisfactory biocompatibility, stable degradability, and osteogenic ability in vitro. Moreover, the ability to anchor Bio-Oss and sustained osteogenesis of L-DPZ result in satisfactory healing in calvarial bone defect models in rabbits, as observed by increased bone thickness and the ingrowth of new bone tissue. These results are expected to demonstrate solutions to clinical dilemmas such as comminuted bone fracture fixation, bone defect reconstruction, and teeth dislocation replantation.

Exosomes from adipose-derived stem cells regulate M1/M2 macrophage phenotypic polarization to promote bone healing via miR-451a/MIF.

OBJECTIVES: Bone defects caused by diseases and trauma are usually accompanied by inflammation, and the implantation of biomaterials as a common repair method has also been found to cause inflammatory reactions, which affect bone metabolism and new bone formation. This study investigated whether exosomes from adipose-derived stem cells (ADSC-Exos) plays an immunomodulatory role in traumatic bone defects and elucidated the underlying mechanisms. METHODS: ADSC-Exos were loaded by a biomaterial named gelatine nanoparticles (GNPs), physical and chemical properties were analysed by zeta potential, surface topography and rheology. A rat model of skull defect was used for our in vivo studies, and micro-CT and histological staining were used to analyse histological changes in the bone defect area. RT-qPCR and western blotting were performed to verify that ADSC-Exos could regulate M1/M2 macrophage polarization. MicroRNA (miRNA) array analysis was conducted to determine the miRNA expression profiles of ADSC-Exos. After macrophages were treated with a miR-451a mimic, miR-451a inhibitor and ISO-1, the relative expression of genes and proteins was measured by RT-qPCR and western blotting. RESULTS: In vivo, micro-CT and histological staining showed that exosome-loaded GNPs (GNP-Exos) hydrogel, with good biocompatibility and strong mechanical adaptability, exhibited immunomodulatory effect mainly by regulating macrophage immunity and promoting bone tissue healing. Immunofluorescence further indicated that ADSC-Exos reduced M1 marker (iNOS) expression and increased M2 marker (CD206) expression. Moreover, in vitro studies, western blotting and RT-qPCR showed that ADSC-Exos inhibited M1 macrophage marker expression and upregulated M2 macrophage marker expression. MiR-451a was enriched in ADSC-Exos and targeted macrophage migration inhibitory factor (MIF). Macrophages treated with the miR-451a mimic showed lower expression of M1 markers. In contrast, miR-451a inhibitor treatment upregulated the expression of M1 markers and downregulated the expression of M2 markers, while ISO-1 (a MIF inhibitor) treatment upregulated miR-451a expression and downregulated M1 macrophage marker expression. CONCLUSION: GNP-Exos can effectively regulate bone immune metabolism and further promote bone healing partly through immune regulation of miR-451a, which may provide a therapeutic direction for bone repair.

Dynamically Bioresponsive DNA Hydrogel Incorporated with Dual-Functional Stem Cells from Apical Papilla-Derived Exosomes Promotes Diabetic Bone Regeneration.

The regeneration of bone defects in patients with diabetes mellitus (DM) is remarkably impaired by hyperglycemia and over-expressed proinflammatory cytokines, proteinases (such as matrix metalloproteinases, MMPs), etc. In view of the fact that exosomes represent a promising nanomaterial, herein, we reported the excellent capacity of stem cells from apical papilla-derived exosomes (SCAP-Exo) to facilitate angiogenesis and osteogenesis whether in normal or diabetic conditions in vitro. Then, a bioresponsive polyethylene glycol (PEG)/DNA hybrid hydrogel was developed to support a controllable release of SCAP-Exo for diabetic bone defects. This system could be triggered by the elevated pathological cue (MMP-9) in response to the dynamic diabetic microenvironment. It was further confirmed that the administration of the injectable SCAP-Exo-loaded PEG/DNA hybrid hydrogel into the mandibular bone defect of diabetic rats demonstrated a great therapeutic effect on promoting vascularized bone regeneration. In addition, the miRNA sequencing suggested that the mechanism of dual-functional SCAP-Exo might be related to highly expressed miRNA-126-5p and miRNA-150-5p. Consequently, our study provides valuable insights into the design of promising bioresponsive exosome-delivery systems to improve bone regeneration in diabetic patients.

A Logic-Based Diagnostic and Therapeutic Hydrogel with Multistimuli Responsiveness to Orchestrate Diabetic Bone Regeneration.

The regeneration of diabetic bone defects remains challenging as the innate healing process is impaired by glucose fluctuation, reactive oxygen species (ROS), and overexpression of proteinases (such as matrix metalloproteinases, MMPs). A "diagnostic" and therapeutic dual-logic-based hydrogel for diabetic bone regeneration is therefore developed through the design of a double-network hydrogel consisting of phenylboronic-acid-crosslinked poly(vinyl alcohol) and gelatin colloids. It exhibits a "diagnostic" logic to interpret pathological cues (glucose fluctuation, ROS, MMPs) and determines when to release drug in a diabetic microenvironment and a therapeutic logic to program different cargo release to match immune-osteo cascade for better tissue regeneration. The hydrogel is also shown to be mechanically adaptable to the local complexity at the bone defect. Furthermore, the underlying therapeutic mechanism is elucidated, whereby the logic-based cargo release enables the regulation of macrophage polarization by remodeling the mitochondria-related antioxidative system, resulting in enhanced osteogenesis in diabetic bone defects. This study provides critical insight into the design and biological mechanism of dual-logic-based tissue-engineering strategies for diabetic bone regeneration.

Histological and Histomorphometric Evaluation of Applying a Bioactive Advanced Platelet-Rich Fibrin to a Perforated Schneiderian Membrane in a Maxillary Sinus Elevation Model.

BACKGROUND: Schneiderian membrane (SM) perforation is a major complication of maxillary sinus elevation with simultaneous bone grafting, yet under this scenario there is no standard biomaterial that maximizes favorable tissue healing and osteogenic effects. PURPOSE: To compare the effect of advanced platelet-rich fibrin (A-PRF) and collagen membrane (CM) on a perforated SM with simultaneous bone grafting in a maxillary sinus elevation model. MATERIALS AND METHODS: After perforation of the SM was established, 24 animals were randomly divided into two groups: (i) group CM: CM and deproteinized bovine bone mineral (DBBM) (n = 12), (ii) group A-PRF: A-PRF and DBBM (n = 12). Radiographic and histological evaluations were performed at 1 and 4 weeks post-operation. RESULTS: At 1 week, an intact SM was found in group A-PRF. At each time point, the number of inflammatory cells at the perforated site was higher in group CM, and the area of new osteoid formation was significantly greater in group A-PRF (p < 0.0001). At 4 weeks, the osteogenic pattern was shown as from the periphery to the center of the sinus cavity in group A-PRF. CONCLUSION: The higher elasticity, matching degradability, and plentiful growth factors of A-PRF resulted in a fully repaired SM, which later ensured the two osteogenic sources from the SM to generate significant new bone formation. Thus, A-PRF can be considered to be a useful bioactive tissue-healing biomaterial for SM perforation with simultaneous bone grafting.

Impact of diabetes mellitus simulations on bone cell behavior through in vitro models.

Diabetes mellitus (DM) is related to impaired bone healing and an increased risk of bone fractures. While it is recognized that osteogenic differentiation and the function of osteoblasts are suppressed in DM, the influence of DM on osteoclasts is still unclear. Hyperglycemia and inflammatory environment are the hallmark of DM that causes dysregulation of various pro-inflammatory cytokines and alternated gene expression in periodontal ligament cells, osteoblasts, osteocytes, osteoclasts, and osteoclast precursors. A methodological review on conceptual and practical implications of in vitro study models is used for DM simulation on bone cells. Several major databases were screened to find literature related to the study objective. Published literature within last 20 years that used in vitro DM-simulated models to study how DM affects the cellular behavior of bone cells were selected for this review. Studies utilizing high glucose and serum acquired from diabetic animals are the mainly used methods to simulate the diabetic condition. The combination with various simulating factors such as lipopolysaccharide (LPS), hydrogen peroxide (H2O2), and advanced glycation end products (AGEs) have been reported in diabetic situations in vitro, as well. Through screening procedure, it was evident DM-simulated conditions exerted negative impact on bone-related cells. However, inconsistent results were found among different reported studies, which could be due to variation in culture conditions, concentrations of the stimulating factors and cell lineage, etc. This manuscript has concisely reviewed currently existing DM-simulated in vitro models and provides valuable insights of detailed components in simulating DM conditions in vitro. Studies using DM-simulated microenvironment revealed that in vitro simulation negatively impacted periodontal ligament cells, osteoblasts, osteocytes, osteoclasts, and osteoclast precursors. Contrarily, studies also indicated beneficial influence on bone-related cells when such conditions are reversed.

Effects of Programmed Local Delivery from a Micro/Nano-Hierarchical Surface on Titanium Implant on Infection Clearance and Osteogenic Induction in an Infected Bone Defect.

The two major causes for implant failure are postoperative infection and poor osteogenesis. Initial period of osteointegration is regulated by immunocytes and osteogenic-related cells resulting in inflammatory response and tissue healing. The healing phase can be influenced by various environmental factors and biological cascade effect. To synthetically orchestrate bone-promoting factors on biomaterial surface, built is a dual delivery system coated on a titanium surface (abbreviated as AH-Sr-AgNPs). The results show that this programmed delivery system can release Ag+ and Sr2+ in a temporal-spatial manner to clear pathogens and activate preosteoblast differentiation partially through manipulating the polarization of macrophages. Both in vitro and in vivo assays show that AH-Sr-AgNPs-modified surface renders a microenvironment adverse for bacterial survival and favorable for macrophage polarization (M2), which further promotes the differentiation of preosteoblasts. Infected New Zealand rabbit femoral metaphysis defect model is used to confirm the osteogenic property of AH-Sr-AgNPs implants through micro-CT, histological, and histomorphometric analyses. These findings demonstrate that the programmed surface with dual delivery of Sr2+ and Ag+ has the potential of achieving an enhanced osteogenic outcome through favorable immunoregulation.

Strontium Ranelate Incorporated Enzyme-Cross-Linked Gelatin Nanoparticle/Silk Fibroin Aerogel for Osteogenesis in OVX-Induced Osteoporosis.

Osteoporosis is a wide-range disease with a negative impact on bone defect healing. Strontium ranelate (SR) has promising osteogenic potential for its dual function on stimulating osteoblasts and inhibiting osteoclast activity. However, it has limitations for its dose-dependent effect and side effects on systemic applications. Here, a sequentially cross-linking strategy including enzyme-cross-linking through tyrosinase from mushroom and physical folding is acquired to create SR loaded gelatin nanoparticle/silk fibroin aerogel (abbreviated as S/G-Sr-MT) with drug release controlling capacity. The results showed successful enzyme-cross-linking, excellent spatial structure, and enhanced mechanical properties of S/G-Sr-MT. Even Sr2+ loading and stable release with markedly inhibited initial burst release were detected. The biomineralization investigation showed rapid deposition of hydroxyapatite on the surface of S/G-Sr-MT. In vitro, spreading morphology and higher osteogenic gene expression of MC3T3-E1 seeded on S/G-Sr-MT were observed compared to other groups after 7 day culturing. In vivo, S/G-Sr-MT showed an obvious osteogenic capacity in calvaria defects of ovariectomized rats in which high Runx2 expression and inhibited TRAP activity were observed. Such results suggested the S/G-Sr-MT scaffold could stimulate osteogenic differentiation of osteoblasts while inhibiting osteoclast behaviors in vivo. These findings highlight the potential osteogenic ability and clinical application of SR incorporated enzyme-cross-linked scaffold in ovariectomized (OVX) bone healing.

3D cone beam computed tomography reconstruction images in diagnosis of ameloblastomas of lower jaw: A case report and mini review.

Cone beam computed tomography (CBCT) has obvious advantages over regular radiography in diagnosis of complex diseases. Objective of this study is to report a case of a mandibular jaw ameloblastoma recurring cyst, which represents a benign tumor of odontogenic epithelium, using CBCT imaging technology. CBCT examination of the patient suffering with recurrent lower jaw cyst (relapsing four years after surgery) showed a decrease in irregular bone density and appearance of a honeycomb pattern (3.5 cm×2.5 cm×1.8 cm) in the right lower jaw. This suggests that the lesion is more likely to be an ameloblastoma. Preoperative tissue biopsy and pathological examination of surgical sample confirmed the diagnosis. Surgical resection of the diseased tissue and autogenous bone grafting in the mandible was performed. Postoperative CBCT examination showed that the bone defect healed well, without recurrence of the tumor 22 months postoperatively. In conclusion, the rotated 3D CBCT images clearly displays the exact size, location, borders and internal changes of the tumor in the jaw cyst itself and the adjacent tissues. Thus, the dental CBCT allows clinicians to better evaluate lesions, leading to better treatment outcomes.