Bone Defect Model Research Articles

Universal Hydrogel Carrier Enhances Bone Graft Success: Preclinical and Clinical Evaluation.

Orthopedic, maxillofacial, and complex dentoalveolar bone grafting procedures that require donor-site bone harvesting can be associated with post-surgical complications. There has been widespread adoption of exogenously sourced particulate bone graft materials (BGM) for bone regenerative procedures; however, the particulate nature of these materials may lead to compromised healing outcomes, mainly attributed to structural collapse of the BGM, prolonged tissue healing. In this study, a fully synthetic thermoresponsivehydrogel-based universal carrier matrix (TX) that forms flowable and shapable putties with different BGMs while spatially preserving the particles in a 3D scaffold at the implantation site is introduced. The potential synergistic effect of the carrier is investigated in combination with particulate demineralized bone matrix (DBM) in a standard muscle pouch nude mice model (n = 24) as well as in a rabbit femoral critical-sized cortico-cancellous bone defect model (n = 9). Finally, the clinical usability, safety, and efficacy of the carrier for the delivery of deproteinized bovine bone mineral (DBBM) are evaluated in a controlled clinical trial for extraction socket alveolar ridge preservation (ARP) (n = 11 participants). Overall, theTX carrier improved the delivery of different types of BGMs, maintaining these spatially at the implantation site with minimal inflammatory responses, resulting in favorable bone regenerative outcomes.

Masquelet Inspired in Vivo Engineered Extracellular Matrix as Functional Periosteum for Bone Defect Repair and Reconstruction.

The Masquelet technique that combines a foreign body reaction (FBR)-induced vascularized tissue membrane with staged bone grafting for reconstruction of segmental bone defect has gained wide attention in Orthopedic surgery. The success of Masquelet hinges on its ability to promote formation of a "periosteum-like" FBR-induced membrane at the bone defect site. Inspired by Masquelet's technique, here a novel approach is devised to create periosteum mimetics from decellularized extracellular matrix (dECM), engineered in vivo through FBR, for reconstruction of segmental bone defects. The approach involved 3D printing of polylactic acid (PLA) template with desired pattern/architecture, followed by subcutaneous implantation of the template to form tissue, and depolymerization and decellularization to generate dECM with interconnected channels. The dECM matrices produces from the same mice (autologous) or from different mice (allogenic) are used as a functional periosteum for repair of structural bone allograft in a murine segmental bone defect model. This study shows that autologous dECM performed better than allogenic dECM, further permitting local delivery of low dose BMP-2 to enhance allograft incorporation. The success of this current approach can establish a new line of versatile, patient-specific, and periosteum-like autologous dECM for bone regeneration, offering personalized therapeutics to patients with impaired healing.

An injectable multi-functional composite bioactive hydrogel for bone regeneration via immunoregulatory and osteogenesis effects

Bone defects represent a prevalent and significant challenge in clinical practice. Given the inflammatory microenvironment at injury sites and the requirement for endogenous cell and tissue infiltration, there is an urgent need for an ideal biomaterial that can modulate inflammation and promote bone regeneration. We developed an innovative injectable hydrogel (CH@PUE&MSN) designed for immunomodulation and bone regeneration through in situ self-assembly, incorporating puerarin and chitosan with mesoporous silica nanoparticles. In vitro experiments demonstrated that this multifunctional injectable hydrogel promotes tissue cell regeneration, reduces inflammation, inhibits osteoclast formation, induces the migration and differentiation of bone marrow mesenchymal stem cells, and facilitates bone regeneration. Furthermore, we conducted an extensive in vivo evaluation using a bone defect model, employing advanced imaging and histological analyses. Our findings indicate that this multifunctional injectable hydrogel is a promising bioactive material for bone regeneration and presents a novel strategy for the clinical management of bone defects.

3D Printed Titanium Scaffolds with Bi-Directional Gradient QK-Functionalized Surface.

3D printed titanium scaffold has promising applications in orthopedics. However, the bioinert titanium presents challenges for promoting vascularization and tissue growth within the porous scaffold for stable osteointegration. In this study, a modular porous titanium scaffold is created using 3D printing and a gradient-surface strategy to immobilize QK peptide on the surface with a bi-directional gradient distribution. This design featured high peptide density in the interior and low peptide density on both ends, aiming to induce cell migration from ends to interior and subsequently enhance vascularization and osteointegration within the scaffold. In vitro results showed that besides the inherent bioactivity, the gradient distribution of QK positively correlated with endothelial cell migration and promoted angiogenesis. In vivo assay was performed by a segmental bone defect model in rabbit and a spine repair model in sheep. Various staining and Micro-CT results demonstrated that compared to that with uniformly QK-functionalized surface, the scaffold with bi-directional gradient QK-functionalized surface (Ti-G) significantly encouraged new tissue growth toward the interior of the scaffold, subsequently facilitated angiogenesis and osteointegration. This study provides an effective strategy for enhancing the bioactivity of peptide-functionalized scaffolds through the concept of bi-directional gradients, and holds potential for various 3D printed scaffolds.

Analysis of the Effect of Human Type I Collagen-Derived Peptide on Bone Regenerative Capacity and Comparison with Various Collagen Materials In Vivo.

Background and Objectives: Autologous bone grafting is the first choice for reconstructive surgery in bone defects due to trauma or malignant tumors. However, there is an increasing demand for minimally invasive alternatives involving bone regeneration using artificial materials. Biomimetic materials that replicate the body's microscopic structure, such as Cellnest®, are gaining attention. Cellnest is a xeno-free recombinant peptide based on human type I collagen, containing a rich Arg-Gly-Asp (RGD) motif related to cell adhesion. The aim of this study was to compare the effects of Cellnest with existing collagen materials (Pelnac®, Integra®, Terudermis®) on bone regeneration and elucidate the underlying mechanisms. Materials and Methods: In vivo experiments involved a rat model of calvarial bone defects, in which Cellnest and other collagen materials were implanted into the defect area. Bone formation was assessed after 4 weeks using micro-computed tomography (micro-CT) and histological analysis. In vitro experiments included the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), adhesion, and migration assays, and a real-time polymerase chain reaction using rapidly expanding cells (RECs) to explore the mechanisms of Cellnest's bone regenerative capacity. Results: The micro-CT analysis showed that the regenerated bone area was significantly greater in the Cellnest group (72.3%) than in the Pelnac® (25.5%), Integra® (31.6%), and Terudermis® (38.3%) groups. The histological analysis confirmed similar trends, with Cellnest showing 42.2% bone regeneration, outperforming the other materials. The in vitro assays revealed that Cellnest promoted cell proliferation, adhesion, and migration. Gene expression analysis demonstrated that Cellnest significantly increased the levels of the bone formation markers ALP and COL1. Conclusions: Cellnest, a human type I collagen-like peptide rich in RGD motifs, enhances bone regeneration by promoting MSC adhesion and migration, and bone formation-related gene expression. The findings suggest its potential as an effective material for bone defect reconstruction.

Phase-transformed lactoferrin/strontium-doped nanocoatings enhance antibacterial, anti-inflammatory and vascularised osteogenesis of titanium.

Failure of orthopedic implants due to localized bacterial infections, inflammation and insufficient blood supply is always problematic. In this study, strontium-doped titanium dioxide nanotubes (STN) were firstly prepared on titanium surface, and then lactoferrin (LF) was loaded into strontium-doped nanotubes (STN) by the phase transition method, eventually the LF/TCEP-STN composite coating was successfully prepared. With the innate antimicrobial properties of LF, LF/TCEP-STN was effected against E. coli and S. aureus. Cellular assays showed that RAW264.7 (immune), HUVEC (angiogenic) and MC3T3-E1 (osteogenic) exhibited good adhesion and proliferative activity on the surface of LF/TCEP-STN. At the molecular level, LF/TCEP-STN modulated RAW264.7 polarization toward M2-type while promoting MC3T3-E1 differentiation toward osteogenesis. Meanwhile LF/TCEP-STN coating effectively promoted angiogenesis. The results of the bone defect model with or without infection demonstrated that the LF/TCEP-STN material had good anti-inflammatory, antibacterial, and vascularization-promoting osteogenesis. In addition, LF/TCEP-STN offered excellent blood compatibility and biosafety. As a multifunctional coating on implant surfaces, the study's results highlighted the viability of LF/TCEP-STN and offered fresh concepts for the clinical design of next-generation artificial bone implants with antibacterial, anti-inflammatory, and osteogenic properties.

Mesoporous Lanthanum-Doped Magnesium Phosphate Nanopowders Promote Healing of Critical-Size Bone Defects: An InVivo Study.

Treating severe bone deformities and abnormalities continues to be a major clinical hurdle, necessitating the adoption of suitable materials that can actively stimulate bone regeneration. Magnesium phosphate (MP) is a material that has the ability to stimulate the growth of bones. The current study involved the synthesis of mesoporous MP and lanthanum (La)-doped nanopowders using a chemical precipitation approach. The nanopowders were analyzed using several techniques, including XRD, FTIR, HR-TEM, BET, XPS, and FE-SEM. The results confirmed the nanopowders' size of less than 40 nm and the successful incorporation of La3+ ions into the MP structure. The bioactivity of the materials was assessed invitro using simulated bodily fluid (SBF) at 37°C for a duration of 14 days in a shaker incubator (50 rpm). The SEM showed that a bone-like apatite layer formed quickly on the nanopowders' surface, proving that they have unique bioactive properties. The EDX spectra confirmed the presence of Ca, P, Mg, and La elements after immersion in SBF. The MP nanopowders, both with and without La doping, demonstrated the capacity to stimulate bone formation in a rat femoral bone defect model over a 28-day duration. Radiographic and histological studies showed that the La-doped MP nanopowders greatly improved bone repair and regeneration in comparison to the La-free nanopowders. Finally, the readily producible mesoporous MP nanomaterials, especially those with increased La doping (up to 7 wt%), exhibit significant potential for the restoration of large bone defects. Hence, fabricated nanopowders have immense promise for repairing bone criterion defects.

Small but mighty: nanoemulsion particle size dictates bone regeneration potential of FTY720.

The burgeoning field of nano-bone regeneration is yet to establish a definitive optimal particle size for nanocarriers. This study investigated the impacts of nanocarrier's particle size on the bone regeneration efficacy of fingolimod (FTY720)-loaded nanoemulsions. Two distinct particle sizes (60 and 190 nm, designated as NF60 and NF190, respectively) were produced using low-energy and high-energy emulsion techniques, maintaining a consistent surfactant, co-surfactant, and oil. In vitro studies using rat mesenchymal stem cells revealed that both NF60 and NF190 exhibited cell viability and reduced lactate dehydrogenase. Interestingly, NF60 demonstrated superior antioxidant properties, significantly reducing nitric oxide and intracellular reactive oxygen species (ROS) levels compared to NF190. Furthermore, NF60 significantly enhanced ALP activity and calcium deposition during osteogenic differentiation, indicating its potential to promote the early stages of bone formation. In vivo studies using a rat calvarial bone defect model demonstrated that both NF60 and NF190 significantly upregulated the expression of key osteogenic genes, including Runx2, Col, ALP, OCN, and BMP2. Notably, NF60 induced significantly higher expression of Runx2 and BMP2. X-ray and histological investigations revealed significantly improved bone regeneration in the NF60 group, highlighting the superior bone healing potential of smaller FTY720 nanoemulsions, without infiltration of inflammatory cells. The smaller particle size demonstrated superior antioxidant properties, enhanced osteogenic differentiation, and improved bone regeneration, suggesting smaller nanoparticles, with their larger surface area, accelerated drug release rate, and lower viscosity, interact more effectively with cells, leading to increased and effective drug delivery and cellular uptake. Findings highlight the importance of nanocarrier size in optimizing drug delivery for bone tissue engineering applications.

Comparative study of bovine and synthetic hydroxyapatite in micro- and nanosized on osteoblasts action and bone growth.

Hydroxyapatite (HA) is widely used as a bone graft. However, information on the head-to-head osteoinductivity and in vivo performance of micro- and nanosized natural and synthetic HA is still lacking. Here, we fabricated nanosized bovine HA (nanoBHA) by using a wet ball milling method and compared its in vitro and in vivo performance with microsized BHA, nanosized synthetic HA (nanoHA), and microsized synthetic HA (HA). The results showed that the wet ball milling method successfully reduced the particle size of BHA to 40 nm without changing its natural characteristics. NanoBHA was able to maintain cell viability and induce cell proliferation and calcium deposits. NanoBHA promoted osteogenic differentiation via OPN as a specific regulator, with a 13-fold greater expression level. NanoBHA and HA also activated ERK1/2 indicated corresponding to the proliferation-differentiation and death of cells, respectively. The calvarial bone defect model showed that nanoBHA induced bone growth based on CT images, which is in line with the histological results showing the presence of bone cells and connective tissue at the nanoBHA implantation site. In conclusion, natural HA outperformed synthetic HA. Our findings will attract interest in further research into nanomaterials and their mechanism of action in bone remodeling.

Osteogenic potential of esculetin-loaded chitosan nanoparticles in microporous alginate/polyvinyl alcohol scaffolds for bone tissue engineering.

Bone tissue engineering (BTE) is an emerging strategy for the treatment of critical bone defects using biomaterials and cells. Esculetin (ES), a coumarin phytocompound, has demonstrated therapeutic potential, although its osteogenic effects remain insufficiently explored. Owing to its hydrophobic nature, which limits its bioavailability, this study developed a drug delivery system using chitosan nanoparticles (nCS) to achieve sustained release of ES. These ES-loaded nCS nanoparticles were incorporated into biocomposite scaffolds composed of alginate (Alg) and polyvinyl alcohol (PVA) using freeze-drying. The synthesized nCS-ES nanoparticles exhibited spherical morphology with a uniform size distribution, ranging from 105 to 117nm, and demonstrated excellent entrapment efficiencies (94.07 to 97.61%). The nanoparticles displayed high zeta potential values (+27.8 to +33.2mV), ensuring stable dispersion. The biocomposite scaffolds exhibited a uniform distribution of pores, with pore diameters ranging from 106±14μm to 112±14μm. The biocomposite scaffolds exhibited excellent swelling, protein adsorption, biodegradation, and biomineralization properties. The ES-loaded scaffolds showed sustained ES release, promoting osteogenesis in vitro, with the activation of the Wnt/β-catenin signaling pathway. In vivo studies using a rat tibial bone defect model further confirmed that these scaffolds stimulated new bone formation, highlighting the ES's potential for BTE applications.

Bortezomib-releasing silica-collagen xerogels for local treatment of osteolytic bone- and minimal residual disease in multiple myeloma

BackgroundAccumulation of malignant plasma cells in the bone marrow causes lytic bone lesions in 80% of multiple myeloma patients. Frequently fracturing, they are challenging to treat surgically. Myeloma cells surviving treatment in the presumably protective environment of bone lesions impede their healing by continued impact on bone turnover and can explain regular progression of patients without detectable minimal residual disease (MRD). Locally applicable biomaterials could stabilize and foster healing of bone defects, simultaneously delivering anti-cancer compounds at systemically intolerable concentrations, overcoming drug resistance.MethodsWe developed silica-collagen xerogels (sicXer) and bortezomib-releasing silica-collagen xerogels (boXer) for local treatment of osteolytic bone disease and MRD. In vitro and in vivo (tissue sections) release of bortezomib was assessed by ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Material impact on bone formation was assessed in vitro regarding osteoclast/osteoblast numbers and activity. In vivo, drilling defects in a rat- and the 5T33-myeloma mouse model were treated by both materials and assessed by immunohistochemistry, UPLC-MS/MS, µCT, and ToF-SIMS. The material’s anti-myeloma activity was assessed using ten human myeloma cell lines (HMCLs) and eight primary myeloma cell samples including four patients refractory to systemic bortezomib treatment.ResultssicXer and boXer show primary stability comparable to trabecular bone. Granule size and preparation method tailor degradation as indicated by release of the xerogel components (silica and collagen) and bortezomib into culture medium. In vitro, both materials reduce osteoclast activity and do not negatively interfere with osteoblast differentiation and function. The presumed resulting net bone formation with maintained basic remodeling properties was validated in vivo in a rat bone defect model, showing significantly enhanced bone formation for boXer compared to non-treated defects. Both materials induce myeloma cell apoptosis in all HMCLs and primary myeloma cell samples. In the 5T33-myeloma mouse model, both materials stabilized drilling defects and locally controlled malignant plasma cell growth.ConclusionsThe combination of stabilization of fracture-prone lesions, stimulation of bone healing, and anti-tumor effect suggest clinical testing of sicXer and boXer as part of a combined systemic/local treatment strategy in multiple myeloma and non-malignant diseases.

Personalizing β-TCP porous scaffolds to promote osteogenesis: a study of segmental femoral defects in beagle models

The increasing clinical occurrence of segmental bone defects is demanding constant improvements in bone transplantation to overcome issues of limited resources, immune rejection and poor structural complement. This study aimed to develop a personalized bone defect repair modality using 3D-printed tricalcium phosphate (β-TCP) grafts and to assess its osteogenic impacts in a femoral segmental defect model in beagles, as a basis for clinical studies and application. Aβ-TCP scaffold was designed and manufactured using computer-aided design. A 3 cm segmental bone defect model was established in 27 one-year-old male beagles, and were randomly divided into three groups. The control group utilizing only intramedullary fixation, the autograft group with an added autologous bone graft andβ-TCP group using aβ-TCP scaffold. The study animals were monitored for 24 weeks postoperative and assessed for vital signs, imaging, and histological indicators periodically. All of the Beagles underwent successful modeling and experimentation, and were fully ambulatory at four weeks. Postoperative x-rays showed no evidence of loosening or displacement of the intramedullary nails. Micro-CT and histological staining indicated Osteogenesis starting from the fourth week, with the most significant growth seen using autografts (P< 0.05). New bone (NB) formation is seen adhering to the surface and proximal femur after osteotomy. Theβ-TCP group had significantly more evidence of Osteogenesis when compared to the control group (P< 0.05), characterized by NB visible throughout the porous structure and distal residual femur. The control group showed bone formation impeded by fibrosis, showing poor bone growth mainly around the distal end after osteotomy, with poor overall repair outcomes.Conclusion.Growth factor-deficientβ-TCP porous scaffolds demonstrated promising Osteoinductive properties in repairing large segment bone defects in Beagles' femurs. It effectively promoted bone growth and is structurally advantageous for weight bearing long bones.

Early resistance rehabilitation improves functional regeneration following segmental bone defect injury

Many studies have explored different loading and rehabilitation strategies, yet rehabilitation intensity and its impact on the local strain environment and bone healing have largely not been investigated. This study combined implantable strain sensors and subject-specific finite element models in a 2 mm rodent segmental bone defect model. After injury animals were underwent high or low intensity rehabilitation. High intensity rehabilitation increased local strains within the regenerative niche by an average of 44% compared to the low intensity rehabilitation. Finite element modeling demonstrated that resistance rehabilitation significantly increased compressive strain by a factor of 2.0 at week 2 and 4.45 after 4 weeks of rehabilitation. Animals that underwent resistance running had the greatest bone volume and improved functional recovery with regenerated femurs that matched intact failure torque and torsional stiffness values. These results demonstrate the potential for early resistance rehabilitation to improve bone healing.

Enhanced osteogenic potential of iPSC-derived mesenchymal progenitor cells following genome editing of GWAS variants in the RUNX1 gene

Recent genome-wide association studies (GWAS) identified 518 significant loci associated with bone mineral density (BMD), including variants at the RUNX1 locus (rs13046645, rs2834676, and rs2834694). However, their regulatory impact on RUNX1 expression and bone formation remained unclear. This study utilized human induced pluripotent stem cells (iPSCs) differentiated into osteoblasts to investigate these variants’ regulatory roles. CRISPR/Cas9 was employed to generate mutant (Δ) iPSC lines lacking these loci at the RUNX1 locus. Deletion lines (Δ1 and Δ2) were created in iPSCs to assess the effects of removing regions containing these loci. Deletion lines exhibited enhanced osteogenic potential, with increased expression of osteogenic marker genes and Alizarin Red staining. Circularized chromosome conformation capture (4C-Seq) was utilized to analyze interactions between BMD-associated loci and the RUNX1 promoter during osteogenesis. Analysis revealed altered chromatin interactions with multiple gene promoters including RUNX1 isoform, as well as SETD4, a histone methyltransferase, indicating their regulatory influence. Interestingly, both deletion lines notably stimulated the expression of the long isoform of RUNX1, with more modest effects on the shorter isoform. Consistent upregulation of SETD4 and other predicted targets within the Δ2 deletion suggested its removal removed a regulatory hub constraining expression of multiple genes at this locus. In vivo experiments using a bone defect model in mice demonstrated increased bone regeneration with homozygous deletion of the Δ2 region. These findings indicate that BMD-associated variants within the RUNX1 locus regulate multiple effector genes involved in osteoblast commitment, providing valuable insights into genetic regulation of bone density and potential therapeutic targets.

Microgravity’s effects on miRNA-mRNA regulatory networks in a mouse model of segmental bone defects

Rehabilitation from musculoskeletal injuries (MSKI) complicate healing dynamics typically by sustained disuse of bone and muscles. Microgravity naturally allows limb disuse and thus an effective model to understand MSKI. The current study examined epigenetic changes in a segmental bone defect (SBD) mouse model in a prolonged unloading condition after spaceflight (FLT). We further connected potential miRNA–mRNA regulatory pathways impacting bone healing. Here, SBD surgery was performed on nine-week-old male mice that were launched into space for approximately 4 weeks. Sham with no surgery and ground controls were included in the study. The midshaft of the ipsilateral femur (with callus on the surgical mice) as well as the ipsilateral quadriceps tissue were used for analysis. Femur and quadriceps had a distinct miRNA profile. There was a stronger surgery effect as observed by miRNA expression when compared to microgravity effects. Leukopoiesis, granulopoiesis, myelopoiesis of leukocytes, differentiation of myeloid leukocytes, and differentiation of progenitor cells were all altered because of surgery in the femur. The biological functions such as apoptosis, necrosis, and activation of cell migration and viability were altered because of surgery in quadriceps. Integrating the transcriptome and microRNA data indicated pronounced changes because of microgravity. According to pathway analysis, microgravity had a greater impact on the quadriceps tissue than the bone tissue in the absence of surgery. The altered biological functions resulting from microgravity were validated by integrating limited proteomics data to miRNA-mRNA. Thus, this study highlights the importance of dynamic interplay of gene-epigene regulations as they appear to be intrinsically interconnected and influence in combination for the biological outcome.

A cross-linked coating loaded with antimicrobial peptides for corrosion control, early antibacterial, and sequential osteogenic promotion on a magnesium alloy as orthopedic implants.

Magnesium (Mg)-based alloys have been recognized as desirable biodegradable materials for orthopedic implants. However, their clinical application has been limited by rapid degradation rates, insufficient antibacterial and osteogenic-promotion properties. Herein, a MgF2 priming layer was first constructed on AZ31 surface. Then, dopamine and polyphenols (EGCG) were cross-linked onto this AZ31-F surface to promote osteogenesis and further enhance corrosion protection, followed by chemical grafting of antimicrobial peptides (AMPs) via Michael-addition and Schiff-base reaction to confer antibacterial properties. In vitro electrochemical corrosion tests showed that icorr of AZ31-FE/AMPs (4.36×10-7 A/cm2) is two orders of magnitude lower than that of AZ31 (4.17×10-5 A/cm2). In vitro immersion degradation showed that AZ31-FE/AMPs exhibited the lowest hydrogen release (2.38 mL) after 400 h immersion with the lowest hydrogen evolution rate among them. Further, AZ31-FE/AMPs displayed inhibitory effects against S. aureus and E. coil in the initial stage and even after 7 days immersion in PBS (antibacterial rate > 85 %). AZ31-FE/AMPs promoted ALP secretion and calcium nodule formation in MC3T3-E1 cells. Transcriptome sequencing results indicated that osteogenic promotion mechanism of AZ31-FE/AMPs in MC3T3-E1 may involve the PI3K-Akt signalling pathway. Further, AZ31-FE/AMPs enhanced new bone formation when implanted in a rat femoral bone defect model. This coating strategy addresses initial antibacterial and later osteogenesis needs based on the corrosion control, which is crucial for the surface design of Mg-based implants. STATEMENT OF SIGNIFICANCE: It is critical for magnesium-based orthopedic implants to achieve sequential functions in the bone repair process while controlling an appropriate degradation rate. A MgF2 priming layer/phenolic-amine grafted AMPs (antimicrobial peptides) duplex coating was constructed on AZ31 surface in this study. The MgF2 layer provided a basic corrosion protection to magnesium substrate, and dopamine and polyphenols (EGCG) were then cross-linked to the MgF2 pretreated AZ31 to promote osteogenesis and enhance corrosion resistance, followed by chemical grafting of AMPs to confer antibacterial property. This strategy effectively meets the initial need for infection resistance and later osteogenic promotion on the basis of controlling the substrate corrosion rate, thus holding significant implications for the surface design of magnesium-based implants.

An all-in-one “multifunctional hydrogel”: Through antibacterial, anti-inflammatory, and angiogenic to promoting MRSA-infected bone defect repair

Recently, in situ injectable hydrogels have emerged as a promising approach for bone defect healing. However, bone defect healing involves immunomodulation, angiogenesis, and osteogenic differentiation. Furthermore, the repair process is complicated by bacterial infections. Therefore, integrated treatment strategies are urgently needed to attain satisfactory therapeutic outcomes. This study presents an all-in-one multifunctional in situ injectable hydrogel (C/O/Sr/MA hydrogel) designed to repair MRSA-infected bone defects. Notably, carboxymethylated chlorogenic acid insect chitosan (ECCS-CA) exhibited an inhibitory effect on MRSA growth and formed complexes with Sr2+ through metal–ligand bonding. This interaction resulted in a notable reduction in inflammation, accompanied by a shift in macrophage polarization towards the M2 phenotype and enhanced vascularization and bone regeneration. Moreover, ECCS-CA was crosslinked with methacrylic anhydride-oxidized chondroitin sulfate (OCS-MA) via dynamic Schiff base. The cross-linking process enabled the C/O/Sr/MA hydrogel to effectively fill irregularly shaped bone defect sites upon injection and further improved its mechanical properties following UV curing. In rat models of MRSA-infected bone defects, the C/O/Sr/MA hydrogel demonstrated remarkable therapeutic efficacy, promoting bone regeneration, angiogenesis, and collagen deposition while inhibiting inflammatory responses. Overall, this all-in-one multifunctional hydrogel shows excellent promise for bone defect healing.

Efficacy of Bone Regeneration Cell Therapy Using Mesenchymal Stem Cells Originating from Embryonic Stem Cells in Animal Models; Bone Defects and Osteomyelitis.

Bone defects are commonly encountered due to accidents, diseases, or aging, and the demand for effective bone regeneration, particularly for dental implants, is increasing in our aging society. Mesenchymal stem cells (MSCs) are promising candidates for regenerative therapies; however, obtaining sufficient quantities of these cells for clinical applications remains challenging. DW-MSCs, derived from embryonic stem cells and developed by Daewoong Pharmaceutical, exhibit a robust proliferative capacity even after extensive culture. This study explores the therapeutic potential of DW-MSCs in various animal models of bone defects. DW-MSCs were expanded for over 13 passages for in vivo use in rat and canine models of bone defects and osteomyelitis. The research focused on the in vivo osteogenic differentiation of DW-MSCs, the establishment of a fibrin-based system for bone regeneration, the assessment of bone repair following treatment in animal models, and comparisons with commercially available bone grafts. Results showed that DW-MSCs exhibited superior osteogenic differentiation compared to other materials, and the fibrinization process not only preserved but enhanced their proliferation and differentiation capabilities through a 3D culture effect. In both bone defect models, DW-MSCs facilitated significant bone regeneration, reduced inflammatory responses in osteomyelitis, and achieved effective bone healing. The therapeutic outcomes of DW-MSCs were comparable to those of commercial bone grafts but demonstrated qualitatively superior bone tissue restructuring. Our findings suggest that DW-MSCs offer a promising approach for bone regeneration therapies due to their high efficacy and anti-inflammatory properties.

Magnesium-Based Composite Calcium Phosphate Cement Promotes Osteogenesis and Angiogenesis for Minipig Vertebral Defect Regeneration.

Calcium phosphate cement (CPC) is an injectable bone cement with excellent biocompatibility, widely used for filling bone defects of various shapes. However, its slow degradation, insufficient mechanical strength, and poor osteoinductivity limit its further clinical applications. In this study, we developed a novel composite magnesium-based calcium phosphate cement by integrating magnesium microspheres into PLGA fibers obtained through wet spinning and incorporating these fibers into CPC. The inclusion of magnesium-based PLGA fibers enhanced the compressive strength and degradation rate of CPC, with the degradation rate of the magnesium microspheres being controllable to allow for the sustained release of magnesium ions. In vitro experiments showed that magnesium-based CPC enhanced the proliferation and migration of MC3T3-E1 and HUVECs. Additionally, the magnesium-based composite CPC not only enhanced osteogenic differentiation of MC3T3-E1 cells but also promoted angiogenesis in HUVECs. In vivo experiments using a vertebral bone defect model in Bama miniature pigs showed that the magnesium-based composite CPC significantly increased new bone formation. Additionally, compared to the CPC group, this composite exhibited significantly higher levels of osteogenic and angiogenic markers, with no inflammation or necrosis observed in the heart, liver, or kidneys, indicating good biocompatibility. These results suggest that magnesium-based composite CPC, with its superior compressive strength, biodegradability, and ability to promote vascularized bone regeneration, holds promise as a minimally invasive injectable material for bone regeneration.

Mineralized collagen plywood contributes to bone autograft performance

Autologous bone (AB) is the gold standard for bone-replacement surgeries1, despite its limited availability and the need for an extra surgical site. Traditionally, competitive biomaterials for bone repair have focused on mimicking the mineral aspect of bone, as evidenced by the widespread clinical use of bioactive ceramics2. However, AB also exhibits hierarchical organic structures that might substantially affect bone regeneration. Here, using a range of cell-free biomimetic-collagen-based materials in murine and ovine bone-defect models, we demonstrate that a hierarchical hybrid microstructure—specifically, the twisted plywood pattern of collagen and its association with poorly crystallized bioapatite—favourably influences bone regeneration. Our study shows that the most structurally biomimetic material has the potential to stimulate bone growth, highlighting the pivotal role of physicochemical properties in supporting bone formation and offering promising prospects as a competitive bone-graft material.