A Review of the Clinical Side Effects of Bone Morphogenetic Protein-2

Biomaterials and therapeutic strategies designed for tooth extraction socket healing

Tooth extraction is the most commonly performed oral surgical procedure, with a wide range of clinical indications. The oral cavity is a complex microenvironment, influenced by oral movements, salivary flow, and bacterial biofilms. These factors can contribute to delayed socket healing and the onset of post-extraction complications, which can burden patients' esthetic and functional rehabilitation. Achieving effective extraction socket healing requires a multidisciplinary approach. Recent advancements in materials science and bioengineering have paved the way for developing novel strategies. This review outlines the fundamental healing processes and cellular-molecular interactions involved in the healing of extraction sockets. It then delves into the current landscape of biomaterials for socket healing, highlighting emerging strategies and potential targets that could transform the treatment paradigm. Building upon this foundation, this review also presents future directions and identifies challenges associated with the clinical application of biomaterials for extraction socket healing.

Immobilization of BMP-2 in porous hydrogels to spatially regulate osteogenesis

Sustained release of bone morphogenetic protein 2 (BMP-2) is used to enhance bone regeneration, but immobilizing BMP-2 in three-dimensional scaffolds could enable spatial regulation of stem cell differentiation and bone formation. Here, we fabricate porous granular hydrogels presenting BMP-2 on the surface to regulate stem cell growth and differentiation. Immobilization of BMP-2 and cell-adhesive ligands is achieved by surface-specific functionalization of microgels, which are jammed to form microporous hydrogels. Varying surface ligand density regulated spreading, proliferation and differentiation of cells. In addition, modulating the distribution of cell-adhesive ligands and BMP-2 allowed spatial control over cell adhesion and osteogenic differentiation.

Development of a novel rat long-bone nonunion model and efficacy evaluation of a prostaglandin EP4 selective agonist (AKDS001) combined with iliac bone grafting

Aims

Nonunion occurs when a fracture fails to heal permanently, often necessitating surgical intervention to stimulate the bone healing response. Current animal models of long-bone nonunion do not adequately replicate human pathological conditions. This study was intended as a preliminary investigation of a novel rat nonunion model using a two-stage surgical intervention, and to evaluate the efficacy of a selective prostaglandin E2 receptor 4 agonist (AKDS001) as a novel nonunion therapeutic agent compared with existing treatments.

Methods

Initially, Sprague-Dawley rats underwent intramedullary Kirschner wire (K-wire) fixation of a femoral fracture with the interposition of a 2 mm-thick silicon disc. After three weeks, the silicon disc was removed, and the intramedullary K-wire was replaced with plate fixation while maintaining the 2 mm defect. Contrary to the control group (1) that received no treatment, the following therapeutic interventions were performed at injury sites after freshening: (2) freshening group: no grafting; (3) iliac bone (IB) group: IB grafting; (4) AKDS group: AKDS001-loaded microspheres (MS) combined with IB (0.75 mg/ml); and (5) bone morphogenetic protein (BMP) group: grafting of a BMP-2-loaded collagen sponge (10 μg; 0.10 mg/ml). After six weeks, micro-CT (μCT) and histological analysis was performed.

Results

In the control group, the radiological union rate was 0%, and histological findings showed that fracture sites comprised fibrous scar tissue, resembling the histology of human nonunion. The union rates in the freshening, IB, AKDS, and BMP groups were 16.7%, 0%, 62.5%, and 50.0%, respectively. The AKDS group demonstrated a significantly higher union rate than the IB group (p = 0.026). μCT and histological analysis indicated that the quality of newly formed bone was superior in the AKDS group than in the BMP group.

Conclusion

We developed a novel long-bone nonunion model. The co-therapy of AKDS001-MS and IB grafting presents a promising new treatment for nonunion.

Strategies for promoting neurovascularization in bone regeneration

Bone tissue relies on the intricate interplay between blood vessels and nerve fibers, both are essential for many physiological and pathological processes of the skeletal system. Blood vessels provide the necessary oxygen and nutrients to nerve and bone tissues, and remove metabolic waste. Concomitantly, nerve fibers precede blood vessels during growth, promote vascularization, and influence bone cells by secreting neurotransmitters to stimulate osteogenesis. Despite the critical roles of both components, current biomaterials generally focus on enhancing intraosseous blood vessel repair, while often neglecting the contribution of nerves. Understanding the distribution and main functions of blood vessels and nerve fibers in bone is crucial for developing effective biomaterials for bone tissue engineering. This review first explores the anatomy of intraosseous blood vessels and nerve fibers, highlighting their vital roles in bone embryonic development, metabolism, and repair. It covers innovative bone regeneration strategies directed at accelerating the intrabony neurovascular system over the past 10 years. The issues covered included material properties (stiffness, surface topography, pore structures, conductivity, and piezoelectricity) and acellular biological factors [neurotrophins, peptides, ribonucleic acids (RNAs), inorganic ions, and exosomes]. Major challenges encountered by neurovascularized materials during their clinical translation have also been highlighted. Furthermore, the review discusses future research directions and potential developments aimed at producing bone repair materials that more accurately mimic the natural healing processes of bone tissue. This review will serve as a valuable reference for researchers and clinicians in developing novel neurovascularized biomaterials and accelerating their translation into clinical practice. By bridging the gap between experimental research and practical application, these advancements have the potential to transform the treatment of bone defects and significantly improve the quality of life for patients with bone-related conditions.

Usage Trends and Safety Profile of Recombinant Human Bone Morphogenetic Protein-2 for Spinal Column Tumor Surgery: A National Matched Cohort Analysis

STUDY DESIGN

Retrospective Cohort Analysis.

OBJECTIVE

The purpose of this study is to investigate national rates of rhBMP-2 utilization in spinal tumor surgery and examine its association with postoperative complications, revisions, and carcinogenicity.

METHODS

All patients diagnosed with primary or metastatic spinal tumors with subsequent surgical intervention involving a spinal fusion procedure were identified in PearlDiver. Patients were 1:1 matched into 2 cohorts according to rhBMP-2 usage. Postoperative complications and revisions were examined at 1 month, 3 months, 6 months, and 1 year after fusion. New cancer incidence following spinal tumor surgery was assessed until 5 years postoperatively.

RESULTS

A total of 11,198 patients underwent fusion surgery after resection of spinal tumors between 2005 and 2020, with 909 cases reporting the use of rhBMP-2 (8.1%). An annualized analysis revealed that the proportion of spine tumor fusion procedures utilizing rhBMP-2 has been significantly decreasing (R2 = .859, P < .001), with the most recent annual utilization rate at 1.1%. At least 3 months after surgery, significantly increased incidences of surgical site (11.4% vs 3.3%, P = .03) and systemic infections (8.1% vs 1.6%, P = .02) were observed in patients who underwent fusion with rhBMP-2. Across all time points, no significant differences were observed in survival, implant removal, revision rates, or new cancer diagnoses.

CONCLUSION

This analysis demonstrated significantly declining national utilization rates. Spinal tumor cases utilizing rhBMP-2 sustained greater rates of surgical site and systemic infections. rhBMP-2 usage did not significantly reduce the risk of mortality, implant failure, or reoperation.

Alginate Beads Encapsulating Hydroxyapatite Microparticle and BMP-2 for Long Bone Defect Regeneration: A Pilot Study

BACKGROUND/AIM

Large bone defects caused by trauma, infection, tumor excision, and non-union fractures are challenging to treat. Mechanical stability, appropriate osteoconductive bone grafts, and osteoinductive growth factors are necessary for bone regeneration in long bone diaphyseal defects. This study aimed to investigate the efficiency of a hybrid bone scaffold formed using hydroxyapatite (HAp) and bone morphogenetic protein (BMP)-2-containing alginate beads, combined with a barrier membrane, in promoting new bone formation in a rabbit radial segmental defect model.

MATERIALS AND METHODS

Nine rabbits were divided into two groups depending on the type of implant: Alginate beads containing HAp microparticles in phosphate-buffered saline (n=5) or BMP-2 (n=4). A 10-mm radial segmental defect was stabilized using a bone plate and screws, wrapped with an absorbable collagen membrane, and filled with alginate beads. Bone healing at the defect site was assessed via radiography, micro-computed tomography, and histological analysis after 12 weeks.

RESULTS

The BMP-2/HAp alginate bead group showed significantly increased bone volume, polar moment of inertia, and periosteal callus ossification, along with a decreased fibrous infiltration at the defect site. Conversely, the BMP-2-unloaded HAp bead group exhibited membrane degradation, with no hard callus formation at the defect site. Therefore, HAp- and BMP-2-encapsulating alginate beads provided sufficient osteoconductive and osteoinductive support for long bone defect repair.

CONCLUSION

BMP-2/HAp alginate beads, combined with an appropriate collagen membrane and proper internal fixation, may be an effective treatment strategy for long bone segmental defects.

The role of rhBMP-2 in mandibular bone regeneration following tooth extraction through HIF-1α and VEGF-A expression: An Immunohistochemical study

Background

Dentists frequently conduct tooth extractions when there is damage to the tooth or the tissue that supports it. When a tooth is extracted, the alveolar bone will sustain injury. Most of the initial bone volume is lost following the healing phase after extraction. Rehabilitation must start as soon as a tooth is missing, mainly because the alveolar bone is severely damaged during the tooth extraction, particularly in the buccal region where the tooth is removed. Dental implant is one method of replacing lost teeth. One of the most important elements influencing the clinical result of dental implants is a change in the dimension of the alveolar bone. Several bone-grafting techniques, such as socket preservation techniques, have been developed to increase the volume of bone throughout the healing phase after tooth extraction. This study aims to assess the impact rhBMP-2 on creating bone regeneration through VEGF and HIF-1α in the mandibular socket post-extraction in Wistar rats.

Method

On the anterior side of the mandible, in the socket area where the tooth was extracted, rhBMP-2 was injected into the socket, and the xenograft material was applied with a syringe. Male, 9-week-old Wistar rats were chosen (n = 30).

Result

Our statistical evaluations have revealed a significantly higher VEGF-A and HIF-1α expression post-extraction of the rhBMP-2 and xenograft group compared to other group treatments. These findings are significant as they provide a deeper understanding of the mechanisms involved in bone regeneration post-extraction.

Conclusion

Our study suggests that injecting rhBMP-2 into the grafted material and socket extraction during GBR dramatically increases the expression of VEGF-A and HIF-1α. These findings have the potential to significantly impact oral surgery and regenerative dentistry, opening up new possibilities for enhancing bone regeneration techniques.

Biological Augmentation Using Electrospun Constructs with Dual Growth Factor Release for Rotator Cuff Repair

Surgical reattachment of tendon to bone is the standard therapy for rotator cuff tear (RCT), but its effectiveness is compromised by retear rates of up to 94%, primarily due to challenges in achieving successful tendon-bone enthesis regeneration under natural conditions. Biological augmentation using biomaterials has emerged as a promising approach to address this challenge. In this study, a bilayer construct incorporates polydopamine (PDA)-mediated bone morphogenetic protein 2 (BMP2) and BMP12 in separate poly(lactic-co-glycolic acid) (PLGA) fiber layers to promote osteoblast and tenocyte growth, respectively, and intermediate fibrocartilage formation, aiming to enhance the regenerative potential of tendon-bone interfaces. The lower layer, consisting of PLGA fibers with BMP2 immobilization through PDA adsorption, significantly accelerated osteoblast growth. Concurrently, the upper BMP12@PLGA-PDA fiber mat facilitated fibrocartilage formation and tendon tissue regeneration, evidenced by significantly elevated tenocyte viability and tenogenic differentiation markers. Therapeutic efficacy assessed through in vivo RCT models demonstrated that the dual-BMP construct augmentation significantly promoted the healing of tendon-bone interfaces, confirmed by biomechanical testing, cartilage immunohistochemistry analysis, and collagen I/II immunohistochemistry analysis. Overall, this combinational strategy, which combines augmentation patches with the controlled release of dual growth factors, shows great promise in improving the overall success rates of rotator cuff repairs.

Gene-activation of surface-modified 3D printed calcium phosphate scaffolds

Large volume bone defects that do not spontaneously heal despite surgical stabilization ("critical-sized" defects) remain a challenge to treat clinically. Recent research investigating bone regenerative implants made from 3D printed materials have shown promise as a potential alternative to current treatment methods, such as autografting, allografting, and multi-step surgical interventions. Recent work has shown that implanting 3D printed calcium phosphate cement (CPC) scaffolds loaded with bone morphogenetic protein-2 (BMP-2) can provide a one-step surgical intervention that has similar bone healing outcomes to a popular two-step intervention: the Masquelet technique. The aim of this study was to investigate whether a 3D printed CPC scaffold loaded with a lyophilized polyplex gene-delivery formulation could serve as an alternative to loading BMP-2 protein onto such scaffolds. We 3D printed CPC scaffolds, hardened them with multiple methods, and explored the impact of these hardening methods on surface texture, mechanical strength, osteogenic differentiation, and ion flux. We then gene-activated these materials with cationic polyplexes containing plasmid DNA encoding reporter genes to investigate transfection from the gene-activated scaffolds. We found that incubating CPC scaffolds in aqueous solutions after initial hardening in a humid environment could enhance scaffold mechanical strength (compressive strength of 21.28 MPa vs. 6.54 MPa) and osteogenic differentiation. We also found that when we increased the total surface area of the CPC material exposed to polyplex solutions, there was a reduction in transfection via adsorption of polyplexes to the CPC surface. This study shows that 3D printed, gene-activated CPC scaffolds are a promising avenue for future exploration in the field of bone regeneration, though the level of gene expression induced by the scaffolds must be improved.

Global Practices and Preferences in the Use of Osteobiologics for Anterior Cervical Discectomy and Fusion: A Cross-Sectional Study

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To assess global practices and preferences in the use of osteobiologics for anterior cervical discectomy and fusion (ACDF) and identify factors influencing the choice of specific osteobiologics.

METHODS

An online survey developed by AO Spine was distributed to spine surgeons worldwide. The survey captured demographic characteristics, osteobiologic use and related information (i.e., previous training, practice patterns, etc.), and factors influencing osteobiologic choice in ACDF. Descriptive statistics, Chi-square tests, and multiple logistic regression were used to analyze responses, focusing on the associations between osteobiologic use and variables such as training, cost awareness, and regional practices.

RESULTS

Responses from 458 surgeons revealed regional variability in osteobiologic preferences. Autologous iliac crest bone graft (AICBG) was predominant in Asia Pacific and Middle East, while allograft and demineralized bone matrix were favored in North America and Latin America (P < 0.0001). Over half of the respondents (79.7%) lacked formal training in osteobiologics, and 53.1% were unaware of related costs. Surgeons residing in the Asia Pacific region (OR: 0.47, 95% CI: 0.26-0.84, P = 0.0114), without formal training (OR: 0.53, 95% CI: 0.29-0.97, P = 0.0429), or using cages less often (OR: 0.15, 95% CI: 0.06-0.34, P < 0.0001) were less likely to utilize osteobiologics. Osteobiologic use was also more common when related costs were not an issue for the practitioner (OR: 2.32, 95% CI:1.47-3.70, P = 0.0004).

CONCLUSIONS

Significant variation exists in osteobiologic use in ACDF across global regions, influenced by surgeon training, cost awareness, and institutional resources. Enhanced training and guidelines could improve consistency in osteobiologic application.

Versatile hydrogels prepared by microfluidics technology for bone tissue engineering applications

Bone defects are a prevalent issue resulting from various factors, such as trauma, degenerative diseases, congenital disabilities, and the surgical removal of tumors. Current methods for bone regeneration have limitations. In this context, the fusion of tissue engineering and microfluidics has emerged as a promising strategy in the field of bone regeneration. This study describes the classification of microfluidic devices based on the nature of flow and channel type, as well as the materials and techniques required. An overview of microfluidic methods used to prepare hydrogels and the advantages of using these hydrogels in bone tissue engineering (BTE) combining several basic elements of BTE to highlight its advantages is provided. Furthermore, this work emphasizes the benefits of using hydrogels prepared via microfluidics over conventional hydrogels in BTE because of their controlled release of cargo, they can be used for in situ injection, simplify the steps of single-cell encapsulation and have the advantages of high-throughput and precise preparation. Additionally, organ-on-a-chip models fabricated via microfluidics offer a platform for studying cell and tissue behaviors in an authentic and dynamic environment. Moreover, microfluidic devices can be utilized for noninvasive diagnosis and therapy. Finally, this paper summarizes the preclinical and clinical applications of hydrogels prepared via microfluidics for bone regeneration by focusing on their current developmental status, limitations associated with their application, and future challenges, which underscore their potential impacts on advancing regenerative medicine practices.

2023 International Academy of Toxicologic Pathology (IATP) Satellite Symposium: "Medical Device Safety Assessment: Pathology and Toxicology Perspective"

Medical devices represent a complex category of medicinal products with varying definitions depending on the regional jurisdiction of regulatory agencies. A common aspect of these definitions is that a medical device is intended to be used for specific medicinal purpose where the primary intended action of the device is not achieved through pharmacologic (or other chemical) means. While regional regulatory frameworks for medical devices are different than for pharmaceutical or biological products, medical device manufacturers are required to evaluate the safety and performance of these products in the context of their intended use. In biological safety evaluation, histopathology plays a relevant role in assessing medical device biocompatibility. This manuscript provides a broad overview of biocompatibility assessment with a deeper look at the role of the toxicologic pathologist in assessing innovative and emerging bone therapies. The content of this manuscript is based on individual presentations delivered at the 2023 International Academy of Toxicologic Pathology (IATP) Satellite Symposium held in conjunction with the Annual Congress of the European Society of Toxicologic Pathology (ESTP) on 26 September, in Basel, Switzerland.

Optimizing β-TCP with E-rhBMP-2-infused fibrin for vertical bone regeneration in a mouse calvarium model

Effective reconstruction of large bone defects, particularly in thickness, remains one of the major challenges in orthopedic and dental fields. We previously produced an Escherichia coli-based industrial-scale GMP-grade recombinant human bone morphogenetic protein-2 (E-rhBMP-2) and showed that the combination of E-rhBMP-2 with beta-tricalcium phosphate (β-TCP/E-rhBMP-2) can effectively promote bone reconstruction. However, the limited mechanical strength and poor morphology retention of β-TCP granules are key points that need optimization to obtain more effective grafts and further expand its clinical applications. Therefore, we combined β-TCP/E-rhBMP-2 with fibrin gel to enhance its mechanical properties and usability for vertical bone regeneration. We investigated the mechanical properties and vertical bone regeneration effects of the materials applied, with or without fibrin containing E-rhBMP-2, in a calvarial defect model in mice. Compression tests were conducted to assess the initial stability of the materials. Scanning electron microscopy and Fourier transform infrared spectroscopy were conducted to characterize the presence of fibrin on the scaffold. After 4 and 12 weeks of implantation, micro-computed tomography and histological and immunofluorescent analyses were performed to assess the morphology and volume of the newly formed bone. The fibrin-containing groups had significantly higher initial mechanical strength and higher ability to maintain their morphology in vivo compared to the counterparts without fibrin. However, fibrin gel alone suppressed the bone formation ability of β-TCP/E-rhBMP-2 whereas the presence of high doses of E-rhBMP-2 in fibrin gel resulted in material resorption and enhanced new bone formation. In conclusion, fibrin gel significantly improved the mechanical strength and surgical manageability of the β-TCP/E-rhBMP-2 scaffold, and the addition of E-rhBMP-2 to the fibrin gel further enhanced the vertical bone regeneration and initial structural integrity of the scaffold.

Enhancement of In Vivo Bone Regeneration by the Carbohydrate Derivative DP2

Background/Objectives: Delays in bone healing and complications of remodeling constitute a major medical problem-particularly in older adults and patients with comorbidities. Current therapeutic approaches are based on strategies that promote bone regeneration. We recently identified a disaccharide compound (DP2) that enhances in vitro mineralization in human osteoblast cells via the early activation of Runx2 and the induction of osteoblast differentiation. Methods: First, a calcium quantification assay was performed to assess mineralization in MC3T3-E1 cells. Next, microcomputed tomography and histological analyses were used to examine in vivo bone repair in a rat 5 mm cranial defect model following the implantation of DP2 coupled to a micro/macroporous biphasic CaP ceramic (MBCP+) or collagen scaffold. Results: Here, we demonstrated that DP2 induced osteogenic differentiation and significantly elevated calcium matrix deposition in the murine preosteoblast cell line MC3T3-E1. We found that treatment with DP2 coupled to MBCP+ repaired the calvarial defect on post-implantation day 91. It significantly increased bone mineral density starting on day 29 post-treatment. In addition, DP2 did not induce ectopic bone formation. Conclusions: Taken as a whole, these results show that DP2 is a promising candidate treatment for delayed bone healing.

Synthesis and Preclinical Evaluation of a Novel Oxy133-Infused Biomimetic Bone Graft Using a Rat Model of Posterolateral Spinal Fusion

OBJECTIVE

To 1) create a novel tissue-engineered bone graft comprising the osteoinductive oxysterol Oxy133 and 2) compare the osteogenic capability of this novel bone graft with bone graft substitutes previously examined.

METHODS

Oxy133 was homogeneously incorporated into a biomimetic (BioMim) bone graft substitute comprising extracellular matrix and calcium phosphates. Two iterations of the graft were created: one corresponding to an implant-dose of 2.0 mg Oxy133 (BioMim-Oxy133-Lo) and the other corresponding to an implant-dose of 20 mg Oxy133 (BioMim-Oxy133-Hi). Thirty-two male Sprague-Dawley rats were allocated randomly to 4 equally sized groups: 1) BioMim-Oxy133-Lo, 2) BioMim-Oxy133-Hi, 3) absorbable collagen sponge (ACS) with topically applied Oxy133 dissolved in dimethyl sulfoxide (ACS-Oxy133; 20 mg Oxy133/graft), and 4) ACS with topically applied recombinant human bone morphogenetic protein-2 (rhBMP-2) dissolved in water (ACS-rhBMP-2; 5.0 μg rhBMP-2/graft). All animals underwent L4-L5 posterolateral spinal fusion. Spines were harvested 8 weeks postoperatively and analyzed using micro-computed tomography imaging.

RESULTS

Successful fusion was achieved in all animals. Grafts containing Oxy133 had significantly greater bone volume, percent of bone volume per tissue volume (%BV), bone surface density (BSD), and trabecular number (TbN) compared to ACS-rhBMP-2 (P < 0.01 for each). Animals treated with BioMim-Oxy133-Lo had the greatest %BV, BSD, and TbN (P < 0.001 for each), whereas animals treated with ACS-rhBMP-2 had the lowest %BV, BSD, TbN, and trabecular thickness (P < 0.001 for each).

CONCLUSIONS

BioMim-Oxy133 is a novel bone graft that led to superior bone volume and quality compared to ACS-rhBMP-2 in a clinically translatable rat model of spinal fusion. Future work is needed to further evaluate this material as a safe and efficacious bone graft substitute.

The Clinical Efficacy and Safety of ErhBMP-2/BioCaP/β-TCP as a Novel Bone Substitute Using the Tooth-Extraction-Socket-Healing Model: A Proof-of-Concept Randomized Controlled Trial

AIM

This first randomized controlled trial in humans aimed to assess the efficacy and safety of low-dosage Escherichia coli-derived recombinant human bone morphogenetic protein 2 (ErhBMP-2)-incorporated biomimetic calcium phosphate coating-functionalized β-TCP (ErhBMP-2/BioCaP/β-TCP) as a novel bone substitute using the tooth-extraction-socket-healing model.

MATERIALS AND METHODS

Forty patients requiring dental implants after single-root tooth extraction were enrolled in this study and randomly assigned into three groups: ErhBMP-2/BioCaP/β-TCP (N = 15), β-TCP (N = 15) and natural healing (N = 10). New bone volume density from histomorphometric analyses was evaluated 6 weeks post-operatively as the primary outcome, and other histomorphometric analyses, alveolar bone and soft-tissue changes were the secondary outcomes. Safety parameters included adverse events, soft-tissue healing, oral health impact profile, serum BMP-2 concentrations and other laboratory tests.

RESULTS

The findings revealed a significant increase in new bone volume density in patients treated with ErhBMP-2/BioCaP/β-TCP compared to those receiving β-TCP alone. The required bone augmentation procedures during implant placement surgery in the ErhBMP-2/BioCaP/β-TCP group were significantly less than in the natural healing group. There were no significant differences in safety parameters among the three groups.

CONCLUSION

This clinical trial primarily proved the safety and efficacy of ErhBMP-2/BioCaP/β-TCP as a promising bone substitute.

Biofunctional supramolecular injectable hydrogel with spongy-like metal-organic coordination for effective repair of critical-sized calvarial defects

In clinical settings, regenerating critical-sized calvarial bone defects presents substantial problems owing to the intricacy of surgical methods, restricted bone growth medications, and a scarcity of commercial bone grafts. To treat this life-threatening issue, improved biofunctional grafts capable of properly healing critical-sized bone defects are required. In this study, we effectively created anti-fracture hydrogel systems using spongy-like metal-organic (magnesium-phosphate) coordinated chitosan-modified injectable hydrogels (CPMg) loaded with a bioinspired neobavaisoflavone (NBF) component. The CPMg-NBF hydrogels showed outstanding anti-fracture capabilities during compression testing and retained exceptional mechanical stability even after 28 d of immersion in phosphate-buffered saline. They also demonstrated prolonged and stable release profiles of Mg2+ and NBF. Importantly, CPMg-NBF hydrogels revealed robust biphasic mineralization and were non-toxic to MC3T3-E1 cells. To better understand the underlying mechanism of Mg2+ and NBF component, as well as their synergistic effect on osteogenesis, we investigated the expression of key osteogenic proteins in the p38 MAPK and NOTCH pathways. Our results showed that CPMg-NBF hydrogels greatly increased the expression of osteogenic proteins (Runx2, OCN, OPN, BMPS and ALP). In vivo experiments showed that the implantation of CPMg-NBF hydrogels resulted in a significant increase in new bone growth within critical-sized calvarial defects. Based on these findings, we expect that the CPMg-NBF supramolecular hydrogel has tremendous promise for use as a therapeutic biomaterial for treating critical-sized calvarial defects.

Regeneration of Chronic Alveolar Vertical Defects Using a Micro Dosage of rhBMP-2. An Experimental In Vivo Study

OBJECTIVE

The objective of this study is to compare the effect of the location of recombinant human bone morphogenetic protein 2 (rhBMP-2) from the native bone and the periosteum for vertical alveolar bone augmentation.

MATERIALS AND METHODS

Mandibular, chronic, standardized, bilateral, and vertical defects in 12 beagle dogs were evaluated using four modalities: a xenograft alone (XENO; n = 6); rhBMP-2 alone (BMP; n = 6); a technique with rhBMP-2 close to the host bone covered by xenograft (SAN; n = 6); and a technique with rhBMP-2 close to the flap on top of the xenograft (LAS; n = 6). After 8 weeks, a series of in vivo inspections, fluorescence microscopy, histologic and histomorphometric evaluations, and micro-CT analyses.

RESULTS

After 8 weeks of healing, new bone formation correlated with proximity of rhBMP to the perforated membrane with BMP and LAS (p = 0.024). The highest total bone volume was found in the LAS group (45.1% ± 13.3%), followed by the SAN group (35.2% ± 6.7%), BMP group (33.1% ± 11.8%), followed by the XENO group (23.1% ± 6.5%). The SAN group demonstrated frequent seroma formation. Blood vessel formation was more pronounced in the LAS + rhBMP group, with a significant increase of 27.1% compared to the XENO group (p = 0.02). Micro-CT revealed a strong trend for higher bone volume in the BMP group (34.7%) compared to the XENO group (13.6%) (p = 0.06). Only rhBMP-2 groups demonstrated bone formation above the perforated membrane.

CONCLUSION

The location of rhBMP-2 in relation to the biomaterial and periosteum influenced the effectiveness of vertical bone regeneration.

Nanoclay gels attenuate BMP2-associated inflammation and promote chondrogenesis to enhance BMP2-spinal fusion

Bone morphogenetic protein 2 (BMP2) is clinically applied for treating intractable fractures and promoting spinal fusion because of its osteogenic potency. However, adverse effects following the release of supraphysiological doses of BMP2 from collagen carriers are widely reported. Nanoclay gel (NC) is attracting attention as a biomaterial, given the potential for localized efficacy of administered agents. However, the efficacy and mechanism of action of NC/BMP2 remain unclear. This study explored the efficacy of NC as a BMP2 carrier in bone regeneration and the enhancement mechanism. Subfascial implantation of NC containing BMP2 elicited superior bone formation compared with collagen sponge (CS). Cartilage was uniformly formed inside the NC, whereas CS formed cartilage only on the perimeter. Additionally, CS induced a dose-dependent inflammatory response around the implantation site, whereas NC induced a minor response, and inflammatory cells were observed inside the NC. In a rat spinal fusion model, NC promoted high-quality bony fusion compared to CS. In vitro, NC enhanced chondrogenic and osteogenic differentiation of hBMSCs and ATDC5 cells while inhibiting osteoclastogenesis. Overall, NC/BMP2 facilitates spatially controlled, high-quality endochondral bone formation without BMP2-induced inflammation and promotes high-density new bone, functioning as a next-generation BMP2 carrier.

Synergistic enhancement of spinal fusion in preclinical models using low-dose rhBMP-2 and stromal vascular fraction in an injectable hydrogel composite

Spinal fusion surgery remains a significant challenge due to limitations in current bone graft materials, particularly in terms of bioactivity, integration, and safety. This study presents an innovative approach using an injectable hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) hydrogel combined with stromal vascular fraction (SVF) and low-dose recombinant human BMP-2 (rhBMP-2) to enhance osteodifferentiation and angiogenesis. Through a series of in vitro studies and preclinical models involving rats and minipigs, we demonstrated that the hydrogel system enables the sustained release of rhBMP-2, resulting in significantly improved bone density and integration, alongside reduced inflammatory responses. The combination of rhBMP-2 and SVF in this injectable formulation yielded superior spinal fusion outcomes, with enhanced mechanical properties and increased bone mass in both small and large animal models. These findings suggest that this strategy offers a promising and safer alternative for spinal fusion, with strong potential for clinical application.

Reducing Healing Period with DDM/rhBMP-2 Grafting for Early Loading in Dental Implant Surgery

BACKGROUND

Traditionally, dental implants require a healing period of 4 to 9 months for osseointegration, with longer recovery times considered when bone grafting is needed. This retrospective study evaluates the clinical efficacy of demineralized dentin matrix (DDM) combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) during dental implant placement to expedite the osseointegration period for early loading.

METHODS

Thirty patients (17 male, 13 female; mean age 55.0 ± 8.8 years) requiring bone grafts due to implant fixture exposure (more than four threads; ≥ 3.2 mm) were included, with a total of 96 implants placed. Implants were inserted using a two-stage protocol with DDM/rhBMP-2 grafts. Early loading was initiated at two months postoperatively in the mandible and three months in the maxilla. Clinical outcomes evaluated included primary and secondary stability (implant stability quotient values), healing period, bone width, and marginal bone level assessed via cone-beam computed tomography.

RESULTS

All implants successfully supported final prosthetics with a torque of 50Ncm, without any osseointegration failures. The average healing period was 69.6 days in the mandible and 90.5 days in the maxilla, with significantly higher secondary stability in the mandible (80.7 ± 6.7) compared to the maxilla (73.0 ± 9.2, p < 0.001). Histological analysis confirmed new bone formation and vascularization.

CONCLUSION

DDM/rhBMP-2 grafting appears to significantly reduce the healing period, enabling early loading with stable and favorable clinical outcomes.

The guanine nucleotide exchange factor DOCK5 negatively regulates osteoblast differentiation and BMP2-induced bone regeneration via the MKK3/6 and p38 signaling pathways

DOCK5 (dedicator of cytokinesis 5), a guanine nucleotide exchange factor for Rac1, has been implicated in BMP2-mediated osteoblast differentiation, but its specific role in osteogenesis and bone regeneration remained unclear. This study investigated the effect of DOCK5 on bone regeneration using C21, a DOCK5 chemical inhibitor, and Dock5-deficient mice. Osteoblast differentiation and bone regeneration were analyzed using bone marrow mesenchymal stem cells (BMSCs) and various animal models. C21 significantly enhanced osteoblast differentiation and mineral deposition in mouse MC3T3-E1 cells and in human and mouse BMSCs. Dock5 knockout (KO) mice exhibited increased bone mass and mineral apposition rate, with their BMSCs showing enhanced osteoblast differentiation. Calvarial defect and ectopic bone formation models demonstrated significant induction of bone regeneration in Dock5 KO mice compared to wild-type (WT) mice. Moreover, DOCK5 inhibition by C21 in WT mice enhanced BMP2-induced subcutaneous ectopic bone formation. The mechanism responsible for enhanced bone formation induced by DOCK5 inhibition may involve the suppression of Rac1 under TAK1, accompanied by the activation of MKK3/6 and p38 induced by BMP2. These findings strongly suggest that DOCK5 negatively regulates osteoblast differentiation and bone regeneration through signaling pathways involving TAK1, MKK3/6, and p38, providing new insights into potential therapeutic strategies for bone regeneration.

Osteoinductively Functionalized 3D-Printed Scaffold for Vertical Bone Augmentation in Beagle Dogs

OBJECTIVE

To evaluate the efficacy of 3D-printed scaffolds that were osteoinductively functionalized with a bone morphogenetic protein 2 (BMP-2)-incorporated biomimetic calcium phosphate particles (BMP-2-inc. BpNcCaP)/hyaluronic acid (HA) composite gel in vertical bone augmentation in beagle dogs.

MATERIALS AND METHODS

Four Beagle dogs were used in this study. Three months after the extraction of 1st, 2nd, 3rd, and 4th premolars at both sides of the lower jaws of Beagle dogs, one or two critical-size vertical bone defects (4 mm vertical bone defect without buccal and lingual bone) on each side were surgically created. The defects were randomly subjected to the following groups: (1) Control (without bone-defect-filling materials); (2) 3D scaffold; (3) BMP2-inc. BpNcCaP/HA-functionalized 3D scaffold. Six weeks post-surgery, samples were harvested and subjected to micro-CT and histomorphometric analyses.

RESULTS

The struts of the BMP2-inc. BpNcCaP/HA-func. 3D scaffold were covered by a thick layer of cemented irregular particles with an average pore size at 327 ± 27 μm. The BpNcCaP/HA-func. 3D scaffold group bore significantly higher bone volume, bone volume fraction, trabecular number, trabecular thickness, bone mineral density, connectivity density, and bone volumes in three directions (mesiodistal, buccolingual, and apicocoronal) when compared with the groups of Control and 3D scaffold. Moreover, the BMP2-inc. BpNcCaP/HA-func. 3D scaffold group bore significantly lower trabecular separation and exhibited significantly higher bone-to-scaffold contact percentage and newly formed bone area percentage within pores in comparison with 3D scaffold.

CONCLUSIONS

BMP2-inc. BpNcCaP/HA-func. 3D scaffold dramatically enhanced vertical alveolar bone augmentation, which suggests a promising application potential of BMP2-inc. BpNcCaP/HA-func. 3D scaffold in dental clinic.

Regional Gene Therapy for Bone Tissue Engineering: A Current Concepts Review

The management of segmental bone defects presents a complex reconstruction challenge for orthopedic surgeons. Current treatment options are limited by efficacy across the spectrum of injury, morbidity, and cost. Regional gene therapy is a promising tissue engineering strategy for bone repair, as it allows for local implantation of nucleic acids or genetically modified cells to direct specific protein expression. In cell-based gene therapy approaches, a variety of different cell types have been described including mesenchymal stem cells (MSCs) derived from multiple sources-bone marrow, adipose, skeletal muscle, and umbilical cord tissue, among others. MSCs, in particular, have been well studied, as they serve as a source of osteoprogenitor cells in addition to providing a vehicle for transgene delivery. Furthermore, MSCs possess immunomodulatory properties, which may support the development of an allogeneic "off-the-shelf" gene therapy product. Identifying an optimal cell type is paramount to the successful clinical translation of cell-based gene therapy approaches. Here, we review current strategies for the management of segmental bone loss in orthopedic surgery, including bone grafting, bone graft substitutes, and operative techniques. We also highlight regional gene therapy as a tissue engineering strategy for bone repair, with a focus on cell types and cell sources suitable for this application.

Advancements in Hyaluronic Acid Effect in Alveolar Ridge Preservation: A Narrative Review

Background/Objectives: Tooth extraction induces significant alveolar ridge dimensional changes and soft tissue modifications, often leading to challenges in implant placement or conventional prosthetic rehabilitation. Alveolar Ridge Preservation (ARP) strategies aim to mitigate post-extraction resorption of the alveolar ridge, enhancing both the quality and quantity of bone and soft tissue during healing. Hyaluronic acid (HYA) has emerged as a promising biological agent for ARP due to its osteoinductive, antimicrobial, and anti-inflammatory properties. However, the effects of HYA in ARP remain inconsistently reported. This study aims to assess current clinical and preclinical evidence regarding the biological effects of HYA and its application in ARP. Additionally, it evaluates HYA's impact-alone or in combination with other products-on hard and soft tissue dimensional changes, early wound healing, and implant success rates. Methods: A comprehensive electronic literature search was conducted, and studies meeting the inclusion criteria were critically evaluated. Relevant data were extracted from the final selection of articles. Results: Thirteen publications were evaluated. Some studies reported a significantly improved newly formed bone following ARP with intra-socket HYA application as a single approach (p = 0.004). Combining HYA with a bone graft and a free palatal graft resulted in significantly greater amounts of newly formed and mature bone, reduced clinical bone width changes, lower radiographic crestal bone loss (p < 0.01), and diminished radiological volumetric and linear bone resorption (p = 0.018). Short-term follow-up data indicated improved soft tissue healing associated with HYA-based ARP. While HYA appears to have a protective effect on ridge dimensional changes in ARP, other studies reported no significant differences in radiographic bone dimensional changes or soft tissue improvement. Conclusions: The addition of HYA to bone grafts may enhance some ARP outcomes. However, the variability in outcomes and methodologies across the evaluated studies precludes drawing definitive clinical conclusions. Further robust research is needed to clarify HYA's role in ARP. With respect to clinical significance enhancing the understanding of ARP management strategies and their effects on post-extraction sockets empowers clinicians to make more informed decisions. The knowledge of HYA effects facilitates the selection of personalized ARP approaches tailored to optimize outcomes for subsequent interventions.

Sticky Polyelectrolyte Shield for Enhancing Biological Half-Life of Growth Factors

Delivery of secretomes, which includes growth factors, cytokines, and mRNA, is critical in regenerative medicine for cell-to-cell communication. However, the harsh in vivo environment presents significant challenges for secretome delivery. Proteolytic enzymes shorten secretomes' half-lives, and secretomes tend to rapidly diffuse at defect sites. Therefore, a delivery system that ensures prolonged retention and enhanced therapeutic efficacy of secretomes is required. In this study, a Coating Optimized Drug Delivery Enhancement (COD2E) system, a coacervate composed of dopamine functionalized fucoidan and poly-l-lysine, was fabricated for secretome delivery. The dopamine modification significantly enhanced adhesive strength (>7-fold) compared to that of the neat coacervates, which enabled rapid (5 min) and uniform coating ability on collagen sponges. The COD2E system was able to encapsulate fibroblast growth factor (FGF2) and prolong the half-life of FGF2. Notably, its efficacy, demonstrated through a single application of FGF2 encapsulated COD2E on collagen sponge, in a wound model demonstrated a successful tissue repair. The COD2E system is an effective growth factor delivery vehicle since it can protect growth factors, has an antioxidant ability, adheres on various material surfaces, and is hemocompatible.

Ex Vivo Regional Gene Therapy Compared to Recombinant BMP-2 for the Treatment of Critical-Size Bone Defects: An In Vivo Single-Cell RNA-Sequencing Study

Ex vivo regional gene therapy is a promising tissue-engineering strategy for bone regeneration: osteogenic mesenchymal stem cells (MSCs) can be genetically modified to express an osteoinductive stimulus (e.g., bone morphogenetic protein-2), seeded onto an osteoconductive scaffold, and then implanted into a bone defect to exert a therapeutic effect. Compared to recombinant human BMP-2 (rhBMP-2), which is approved for clinical use, regional gene therapy may have unique benefits related to the addition of MSCs and the sustained release of BMP-2. However, the cellular and transcriptional mechanisms regulating the response to these two strategies for BMP-2 mediated bone regeneration are largely unknown. Here, for the first time, we performed single-cell RNA sequencing (10x Genomics) of hematoma tissue in six rats with critical-sized femoral defects that were treated with either regional gene therapy or rhBMP-2. Our unbiased bioinformatic analysis of 2393 filtered cells in each group revealed treatment-specific differences in their cellular composition, transcriptional profiles, and cellular communication patterns. Gene therapy treatment induced a more robust chondrogenic response, as well as a decrease in the proportion of fibroblasts and the expression of profibrotic pathways. Additionally, gene therapy was associated with an anti-inflammatory microenvironment; macrophages expressing canonical anti-inflammatory markers were more common in the gene therapy group. In contrast, pro-inflammatory markers were more highly expressed in the rhBMP-2 group. Collectively, the results of our study may offer insights into the unique pathways through which ex vivo regional gene therapy can augment bone regeneration compared to rhBMP-2. Furthermore, an improved understanding of the cellular pathways involved in segmental bone defect healing may allow for the further optimization of regional gene therapy or other bone repair strategies.

2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside-stimulated dental pulp stem cells-derived exosomes for wound healing and bone regeneration

Background/purpose

-2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) is a bioactive component in the Chinese herb Polygonum multiflorum, recognized for its anti-inflammatory and lipid-lowering properties. Human dental pulp stem cells (hDPSCs) have excellent capabilities in tooth regeneration, wound healing, and neural repair. The exosomes (Exo) released by hDPSCs contain bioactive molecules that influence cell proliferation, differentiation, and immune responses. Therefore, we aimed to unveil the potential of THSG-Exo and evaluate its regenerative capabilities through the in vitro experiment and rat bone defect model.

Materials and methods

The effects of hDPSC-derived exosomes, with or without THSG treatment, on repair and bone regeneration were evaluated through in vitro and in vivo studies. Finally, we conducted a proteomic analysis to meticulously compare the compositional contents of the two types of exosomes.

Results

In vitro data showed that 10 and 100 μM THSG-Exo enhanced cell proliferation and osteogenic differentiation, reducing wound size to 40 % of its original size. In our maxillary bone defect rat model, THSG-Exo significantly increased bone volume, trabecular thickness, and bone density in the bone defect area. In addition, proteomic analysis of THSG-Exo revealed diverse proteins linked to bone differentiation and tissue repair, including bone morphogenetic protein-1 (BMP-1) and tumor necrosis factor (TNF)-α-stimulated gene 6 (TNFAIP6). Our searches in functional databases revealed that THSG-Exo is involved in numerous biological pathways.

Conclusion

THSG-Exo enhanced cell proliferation, wound healing, and osteogenesis in vitro, while also expediting tissue repair and bone regeneration in vivo. The protein diversity of THSG-Exo contributes significant value in both basic and regenerative medicine.

Depletion of MicroRNA-100-5p Promotes Osteogenesis Via Lysine(K)-Specific Demethylase 6B

Senescence and osteogenic differentiation potential loss limited bone nonunion treatment effects of bone marrow-derived mesenchymal stem cells (BMSCs). MiR-100-5p/Lysine(K)-specific demethylase 6B (KDM6B) can inhibit osteogenesis, but their effects on bone union remain unclear. This study aims to investigate the effects of miR-100-5p/KDM6B on osteogenic differentiation and bone defects. Wild-type or microRNA 100 (miR-100) knockdown mice underwent critical-size defect (CSD) cranial surgery and collagen I/poly-γ-glutamic acid scaffold treatment. The crania was observed using microcomputed tomography, hematoxylin and eosin staining, Masson staining, alkaline phosphatase (ALP) staining, immunohistochemistry, and immunofluorescence. Primary-cultured BMSCs transfected with miR-100-5p mimic/inhibitor and KDM6B cDNA were evaluated for osteogenic differentiation using Alizarin Red staining, ALP activity detection, and Western blot analysis. Genetic transcription levels were detected using quantitative reverse transcription polymerase chain reaction. This study found that miR-100 depletion promotes defect healing in mouse calvaria, increases the proportion of new bone and osteoblasts in calvaria, and activates the expression of KDM6B and osteocalcin (OCN) proteins, promoting the transcription of bone morphogenetic protein-2, Runt-related transcription factor 2 (Runx2), OCN, and KDM6B, while methylation of lysine 27 on histone H3 (H3K27me3) decreased. Furthermore, miR-100-5p mimics suppressed osteogenic differentiation by inhibiting KDM6B with increased H3K27me3, ALP, Runx2, OCN, and osteopontin protein expression, while miR-100-5p inhibitors have opposite effects. Moreover, KDM6B can reverse miR-100-5p mimic effects. Notably, scaffolds carrying miR-100-5p mimics/inhibitors transfected BMSCs were placed in CSD mice and found that miR-100-5p inhibitors have a better effect on CSD healing and increase new bone without inflammatory cell infiltration. This study proved that miR-100-5p depletion promotes bone union and osteogenic differentiation of BMSCs via KDM6B/H3K27me3.

Bioactive hydrogels based on lysine dendrigrafts as crosslinkers: tailoring elastic properties to influence hMSC osteogenic differentiation

Dendrigrafts are multivalent macromolecules with less ordered topology and higher branching than dendrimers. Exhibiting a high density of terminal amines, poly-L-lysine dendrigrafts of the fifth generation (DGL G5) allow hydrogel formation with tailorable crosslinking density and surface modification. This work presents DGL G5 as multifunctional crosslinkers in biomimetic PEG hydrogels to favour the osteogenic differentiation of human mesenchymal stem cells (hMSCs). DGL G5 reaction with dicarboxylic-acid PEG chains yielded amide networks of variable stiffness, measured at the macro and surface nanoscale. Oscillatory rheometry and compression afforded consistent values of Young's modulus, increasing from 8 to more than 30 kPa and correlating with DGL G5 concentration. At the surface level, AFM measurements showed the same tendency but higher E values, from approximately 15 to more than 100 kPa, respectively. To promote cell adhesion and differentiation, the hydrogels were functionalised with a GRGDSPC peptide and a biomimetic of the bone morphogenetic protein 2 (BMP-2), ensuring the same grafting concentrations (between 2.15 ± 0.54 and 2.28 ± 0.23 pmols mm-2) but different hydrogel stiffness. 6 h after seeding on functionalised hydrogels in serum-less media, hMSC showed nascent adhesions on the stiffer gels and greater spreading than on glass controls with serum. After two weeks in osteogenic media, hMSC seeded on the stiffer gels showed greater spreading, more polygonal morphologies and increased levels of osteopontin, an osteoblast marker, compared to controls, which peaked on 22 kPa-gels. Together, these results demonstrate that DGL G5-PEG hydrogel bioactivity can influence the adhesion, spreading and early commitment of hMSCs.

Treatment of Bone Defects and Nonunion via Novel Delivery Mechanisms, Growth Factors, and Stem Cells: A Review

Bone nonunion following a fracture represents a significant global healthcare challenge, with an overall incidence ranging between 2 and 10% of all fractures. The management of nonunion is not only financially prohibitive but often necessitates invasive surgical interventions. This comprehensive manuscript aims to provide an extensive review of the published literature involving growth factors, stem cells, and novel delivery mechanisms for the treatment of fracture nonunion. Key growth factors involved in bone healing have been extensively studied, including bone morphogenic protein (BMP), vascular endothelial growth factor (VEGF), and platelet-derived growth factor. This review includes both preclinical and clinical studies that evaluated the role of growth factors in acute and chronic nonunion. Overall, these studies revealed promising bridging and fracture union rates but also elucidated complications such as heterotopic ossification and inferior mechanical properties associated with chronic nonunion. Stem cells, particularly mesenchymal stem cells (MSCs), are an extensively studied topic in the treatment of nonunion. A literature search identified articles that demonstrated improved healing responses, osteogenic capacity, and vascularization of fractures due to the presence of MSCs. Furthermore, this review addresses novel mechanisms and materials being researched to deliver these growth factors and stem cells to nonunion sites, including natural/synthetic polymers and bioceramics. The specific mechanisms explored in this review include BMP-induced osteoblast differentiation, VEGF-mediated angiogenesis, and the role of MSCs in multilineage differentiation and paracrine signaling. While these therapeutic modalities exhibit substantial preclinical promise in treating fracture nonunion, there remains a need for further research, particularly in chronic nonunion and large animal models. This paper seeks to identify such translational hurdles which must be addressed in order to progress the aforementioned treatments from the lab to the clinical setting.

Peptide Hydrogel for Sustained Release of Recombinant Human Bone Morphogenetic Protein-2 In Vitro

This study aimed to investigate the impact of varying the formulation of a specific peptide hydrogel (PepGel) on the release kinetics of rhBMP-2 in vitro. Three PepGel formulations were assessed: (1) 50% v/v (peptides volume/total volume) PepGel, where synthetic peptides were mixed with crosslinking reagents and rhBMP-2 solution; (2) 67% v/v PepGel; (3) 80% v/v PepGel. Each sample was loaded with 12 µg of rhBMP-2 and incubated in PBS. Released rhBMP-2 was quantified by ELISA at 1 h, 6 h, and 1, 2, 4, 7, 10, 14, and 21 days. To explore how PepGel formulations influence rhBMP-2 release, the gel porosities, swelling ratios, and mechanical properties of the three PepGel formulations were quantitatively analyzed. The results showed that rhBMP-2 encapsulated with 50% v/v PepGel exhibited a sustained release over the 21-day experiment, while the 67% and 80% v/v PepGels demonstrated significantly lower rhBMP-2 release rates compared to the 50% formulation after day 7. Higher histological porosity of PepGel was significantly correlated with increased rhBMP-2 release rates. Conversely, the swelling ratio and elastic modulus of the 50% v/v PepGel were significantly lower than that of the 67% and 80% v/v formulations. In conclusion, this study indicates that varying the formulation of crosslinked PepGel can control rhBMP-2 release rates in vitro by modulating gel porosity, swelling ratio, and mechanical properties. Encapsulation with 50% v/v PepGel offers a sustained rhBMP-2 release pattern in vitro; if replicated in vivo, this could mitigate the adverse effects associated with burst release of rhBMP-2 in clinical applications.

The Combination of Bioactive Herbal Compounds with Biomaterials for Regenerative Medicine

Regenerative medicine aims to restore the function of diseased or damaged tissues and organs by cell therapy, gene therapy, and tissue engineering, along with the adjunctive application of bioactive molecules. Traditional bioactive molecules, such as growth factors and cytokines, have shown great potential in the regulation of cellular and tissue behavior, but have the disadvantages of limited source, high cost, short half-life, and side effects. In recent years, herbal compounds extracted from natural plants/herbs have gained increasing attention. This is not only because herbal compounds are easily obtained, inexpensive, mostly safe, and reliable, but also owing to their excellent effects, including anti-inflammatory, antibacterial, antioxidative, proangiogenic behavior and ability to promote stem cell differentiation. Such effects also play important roles in the processes related to tissue regeneration. Furthermore, the moieties of the herbal compounds can form physical or chemical bonds with the scaffolds, which contributes to improved mechanical strength and stability of the scaffolds. Thus, the incorporation of herbal compounds as bioactive molecules in biomaterials is a promising direction for future regenerative medicine applications. Herein, an overview on the use of bioactive herbal compounds combined with different biomaterial scaffolds for regenerative medicine application is presented. We first introduce the classification, structures, and properties of different herbal bioactive components and then provide a comprehensive survey on the use of bioactive herbal compounds to engineer scaffolds for tissue repair/regeneration of skin, cartilage, bone, neural, and heart tissues. Finally, we highlight the challenges and prospects for the future development of herbal scaffolds toward clinical translation. Overall, it is believed that the combination of bioactive herbal compounds with biomaterials could be a promising perspective for the next generation of regenerative medicine. Impact statement This article reviews the combination of bioactive herbal compounds with biomaterials in the promotion of skin, cartilage, bone, neural, and heart regeneration, due to the anti-inflammatory, antibacterial, antioxidative, and proangiogenic effects of the herbal compounds, but also their effects on the improvement of mechanic strength and stability of biomaterial scaffolds. This review provides a promising direction for the next generation of tissue engineering and regenerative medicine.

Local drug delivery challenges and innovations in spinal neurosurgery

The development of novel therapeutics in the field of spinal neurosurgery faces a litany of translational challenges. Achieving precise drug targeting within the confined spaces associated with the spinal cord, canal and vertebra requires the development of next generation delivery systems and devices. These must be capable of overcoming inherent barriers related to drug diffusion, whilst concurrently ensuring optimal drug distribution and retention. In this review, we provide an overview of the most recent advances in the therapeutic management of diseases and disorders affecting the spine, including systems and devices capable of releasing small molecules and biopharmaceuticals that help eliminate pain and restore the mechanical function and stability of the spine. We highlight material-based approaches and minimally invasive techniques that can be employed to provide control over drug release kinetics and improve retention. We also seek to explore how the newest advancements in nanotechnology, biomaterials, additive manufacturing technologies and imaging modalities can be employed in this translational pursuit. Finally, we discuss the landscape of clinical trials and recently approved products aimed at overcoming the complexities associated with drug delivery to the spine.

Extracellular derivatives for bone metabolism

BACKGROUND

Bone metabolism can maintain the normal homeostasis and function of bone tissue. Once the bone metabolism balance is broken, it will cause osteoporosis, osteoarthritis, bone defects, bone tumors, or other bone diseases. However, such orthopedic diseases still have many limitations in clinical treatment, such as drug restrictions, drug tolerance, drug side effects, and implant rejection.

AIM OF REVIEW

In complex bone therapy and bone regeneration, extracellular derivatives have become a promising research focus to solve the problems of bone metabolic diseases. These derivatives, which include components such as extracellular matrix, growth factors, and extracellular vesicles, have significant therapeutic potential. It has the advantages of good biocompatibility, low immune response, and dynamic demand for bone tissue. The purpose of this review is to provide a comprehensive perspective on extracellular derivatives for bone metabolism and elucidate the intrinsic properties and versatility of extracellular derivatives. Further discussion of them as innovative advanced orthopedic materials for improving the effectiveness of bone therapy and regeneration processes.

KEY SCIENTIFIC CONCEPTS OF REVIEW

In this review, we first listed the types and functions of three extracellular derivatives. Then, we discussed the effects of extracellular derivatives of different cell sources on bone metabolism. Subsequently, we collected applications of extracellular derivatives in the treatment of bone metabolic diseases and summarized the advantages and challenges of extracellular derivatives in clinical applications. Finally, we prospected the extracellular derivatives in novel orthopedic materials and clinical applications. We hope that the comprehensive understanding of extracellular derivatives in bone metabolism will provide new solutions to bone diseases.

3D-Printed-Cryogel-Impregnated Functionalized Scaffold Augments Bone Regeneration in Critical Tibia Fracture in Goat

Critical-size bone trauma injuries present a significant clinical challenge because of the limited availability of autografts. In this study, a photocurable composite comprising of polycaprolactone, polypropylene fumarate, and nano-hydroxyapatite (nHAP) (P─P─H) is printed, which shows good osteoconduction in a rat model. A cryogel composed of gelatin-nHAP (GH) is developed to incorporate osteogenic components, specifically bone morphogenetic protein-2 (BMP-2) and zoledronic acid (ZA), termed as GH+B+Z, which is investigated for osteoinductive property in a rat model. Further, a 3D-printed P─P─H scaffold impregnated with GH+B+Z is designed and implanted in a critical-size defect (25 × 10 × 5 mm) in goat tibia. After 4 months, the scaffold is well-integrated with adjacent native bone, with osteoinduction observed in the cryogel-filled region and osteoconduction over the printed scaffold. X-ray radiography and micro-CT analysis showed bone in-growth in the treatment group with 45 ± 1.4% bone volume/tissue volume (BV/TV), while the defect remained unhealed in the control group with BV/TV of 10.5 ± 0.5%. Histology showed significant cell infiltration and matrix deposition over the printed P─P─H scaffold and within the GH cryogel site in the treatment group. Immunohistochemical staining depicted significantly higher normalized collagen I intensity in the treatment group (34.45 ± 2.61%) compared to the control group (4.22 ± 0.78).

Human platelet-derived growth factor-BB (rhPDGF-BB) with collagen matrix for sinus elevation without using a bone graft

BACKGROUND

This case report involves a 38-year-old male who presented to the clinic after experiencing complications from a tooth extraction, including a dislodged root segment in the sinus, a sinus wall fenestration on the palate, a residual bone height (RBH) of 3 mm, and inadequate healing of the soft tissue. He presented for implant placement.

METHODS

Recombinant human platelet-derived growth factor-BB (rh-PDGF-BB) was applied to a wound dressing material and placed in the sinus cavity alongside a 4.8 × 10 mm dental implant (Straumann SP, Straumann, Andover, MA, USA.). As documented in the literature, a graftless sinus lift via a lateral window was performed using a split-thickness flap technique to elevate the sinus membrane, re-establish its integrity, and restore its barrier function.

RESULTS

An 8-month cone beam computed tomography assessment showed a 6.2 mm vertical bone gain and complete implant coverage.

CONCLUSION

This approach provided a successful alternative to shorten treatment duration and achieve favorable radiographic outcomes during early healing.

KEY POINTS

The use of rhPDGF-BB and a collagen matrix in a sinus lift procedure emerges as a practical therapeutic option when grafting might lack predictability and notably consume more treatment time, while also achieving the desired bone height when used with a simultaneously placed implant.

The effects of young and aged, male and female megakaryocyte conditioned media on angiogenic properties of endothelial cells

With aging, the risk of fractures and compromised healing increases. Angiogenesis plays a significant role in bone healing and is impaired with aging. We have previously shown the impact of megakaryocytes (MKs) in regulating bone healing. Notably, MKs produce factors known to promote angiogenesis. We examined the effects of conditioned media (CM) generated from MKs derived from young (3-4-month-old) and aged (22-24-month-old), male and female C57BL/6J mice on bone marrow endothelial cell (BMEC) growth and function. Female MK CM, regardless of age, caused a >65% increase in BMEC proliferation and improved vessel formation by >115%. Likewise, young male MK CM increased vessel formation by 160%. Although aged male MK CM resulted in >150% increases in the formation of vascular nodes and meshes, 62% fewer vessels formed compared to young male MK CM treatment. Aged female MK CM improved migration by over 2500%. However, aged female and male MK CM caused less wound closure. MK CM treatments also significantly altered the expression of several genes including PDGFRβ, CXCR4, and CD36 relative to controls and between ages. Further testing of mechanisms responsible for age-associated differences may allow for novel strategies to improve MK-mediated angiogenesis and bone healing, particularly within the aging population.

Strontium-Doped Whitlockite Scaffolds for Enhanced Bone Regeneration

Bone graft substitutes to repair critical-sized bone fractures have experienced significant development over the last few decades. Among them, whitlockite (WH)-based bone grafts have proven to be effective in mediating bone healing. In the current study, a next generation, nature-inspired scaffold was developed with strontium-functionalized whitlockite nanoparticles (nSrWH) to enhance the intrinsic properties of WH. A series of nSrWH (with 2.5, 5, 7.5% Sr atomic substitution) were fabricated using a rapid-mixing wet precipitation route. Subsequently, the functionalized whitlockite was integrated into a gelatin-chondroitin sulfate scaffold and subjected to both in vitro and in vivo studies to investigate its osteogenic potential. Results indicated that nSrWH-containing scaffolds promoted osteogenic differentiation while inhibiting osteoclast activity. The positive impact of nSrWH was found to be dose-dependent, with the 7.5% Sr atomic substitution exhibiting the most significant results. Furthermore, the scaffold induced superior de novo bone regeneration compared to its undoped counterpart in the mouse calvarial critical-sized defect model. Collectively, these findings suggest that nSrWH nanoparticles inherit the beneficial properties of whitlockite, coupled by the therapeutic effects of Sr2+, operating in concert for an overall enhanced bone regeneration. As such, they constitute promising candidates to meet the biomedical requirements for bioactive bone graft substitutes.

Methyl-Beta-Cyclodextrin Restores Aberrant Bone Morphogenetic Protein 2-Signaling in Bone Marrow Stromal Cells Obtained from Aged C57BL/6 Mice

During aging, disruptions in various signaling pathways become more common. Some older patients will exhibit irregular bone morphogenetic protein (BMP) signaling, which can lead to osteoporosis (OP)-a debilitating bone disease resulting from an imbalance between osteoblasts and osteoclasts. In 2002, the Food and Drug Administration (FDA) approved recombinant human BMP-2 (rhBMP-2) for use in spinal fusion surgeries as it is required for bone formation. However, complications with rhBMP-2 arose and primary osteoblasts from OP patients often fail to respond to BMP-2. Although patient samples are available for study, previous medical histories can impact results. Consequently, the C57BL/6 mouse line serves as a valuable model for studying OP and aging. We find that BMP receptor type Ia (BMPRIa) is upregulated in the bone marrow stromal cells (BMSCs) of 15-month-old mice, consistent with prior data. Furthermore, conjugating BMP-2 with Quantum Dots (QDot®s) allows effective binding to BMPRIa, creating a fluorescent tag for BMP-2. Furthermore, after treating BMSCs with methyl-β-cyclodextrin (MβCD), a disruptor of cellular endocytosis, BMP signaling is restored in 15-month-old mice, as shown by von Kossa assays. MβCD has the potential to restore BMPRIa function, and the BMP signaling pathway offers a promising avenue for future OP therapies.

Treatment of adult spine deformity: A retrospective comparison of bone morphogenic protein and bone marrow aspirate with bone allograft

BACKGROUND  : The use of bone morphogenic protein (BMP-2) in adult spine deformity (ASD) surgery remains controversial more than two decades following its approval for clinical application in spine surgery. This study was performed to assess outcomes in patients undergoing ASD surgery with BMP application compared with a combination of bone marrow aspirate, cancellous bone chips and i-Factor.

METHODS

This was a retrospective cohort study. ASD patients were stratified by use of intra-operative BMP (BMP +) or not (BMA + I) and surveyed for the development of complications and mechanical failure. Quality of life gained following the procedure was evaluated using quality-adjusted life years (QALYs). Cost was calculated using the PearlDiver database and CMS definitions. Multivariable analyses (ANCOVA) and logistic regression were used to adjust for confounding.

RESULTS

512 patients were included (60% BMP +). At baseline, BMP + patients were older (62.5 vs 60.8 years, p < 0.010). Radiographic and quality-of-life metrics did not differ at follow up timepoints (all p > 0.05). BMP use was associated with higher supplemental rod use (OR: 7.0, 1.9 - 26.2, p = 0.004), greater number of levels fused (OR: 1.1, 1.03 - 1.17, p = 0.003) and greater neurological complications (OR: 5.0, 1.3 - 18.7, p = 0.017). Controlling for rod use and levels fused, BMP use was not associated with a lower risk of mechanical complications (OR 0.3, 95% CI: 0.2 - 3.0, p = 0.353), rod breakage (OR: 3.3, 0.6 - 18.7, p = 0.182) or implant failure (OR: 0.3, 0.04 - 1.51). At 2 years, the BMP + cohort exhibited higher overall costs ($108,062 vs $95,144, p = 0.002), comparable QALYs (0.163 vs 0.171, p = 0.65) and higher cost per QALY (p = 0.001) at two years.

CONCLUSIONS

In this analysis, BMP-2 application was not associated with superior outcomes when compared to a less costly biologic alternative (bone marrow aspirate + cancellous bone chips + i-Factor) following ASD surgery. The use of BMP-2 in ASD surgery appears to have reduced cost-efficacy at two years postoperatively.

Effects of Autologous Conditioned Serum on Non-Union After Open Reduction Internal Fixation Failure: A Case Series and Literature Review

Background and Objectives: Non-union is a severe complication of traumatic fracture that often leads to disability and decreased quality of life, with treatment remaining complex due to a lack of standardized protocols. This study examines the effectiveness of autologous conditioned serum (ACS) for non-union in patients who have a failed open reduction internal fixation (ORIF). Materials and Methods: Eleven patients with confirmed non-union at least 9 months post-ORIF or total hip replacement were enrolled. These patients received ACS treatment on the lesion sites once to three times monthly and were followed up. Efficacy was monitored through monthly X-rays to assess callus formation and bone union. Results: Seven patients received ACS three times, three patients received it twice, and the one who underwent total hip replacement received it once. Ten patients achieved union at the last follow-up visit, indicating the effectiveness of ACS in non-union cases unresponsive to ORIF. ACS demonstrated promising results in facilitating bone union in these challenging cases. Conclusions: ACS has the potential as an alternative or adjective treatment for non-union and is worthy of being investigated further for the benefits of patients.

3D-printed biomimetic scaffolds loaded with ADSCs and BMP-2 for enhanced rotator cuff repair

Rotator cuff tear repair poses significant challenges due to the complex gradient interface structure. In the face of disease-related disruptions in the tendon-bone interface (TBI), the strategy of constructing a biomimetic scaffold is a promising avenue. A novel 3D-printed rotator cuff scaffold loaded adipose stem cells (ADSCs), bone morphogenetic protein-2 (BMP-2), and collagen type I (COL I). The efficiency of the slow-release BMP-2 design depended on the dopamine-hyaluronic acid (HAD) and BMP-2 reaction. The cumulative release of BMP-2 was 44.97 ± 5.45% at 4 weeks. The 3D-printed bilayer scaffold, incorporating COL I and BMP-2, effectively promoted the differentiation of ADSCs into osteogenic, tenogenic, and chondrogenic lineages in vitro. The combination of 3D-printed bioactive scaffolds and ADSCs demonstrated a superior repair effect on rotator cuff injuries in vivo. Therefore, these findings indicates that the 3D-printed biomimetic scaffold loaded with ADSCs and BMP-2 holds potential as a promising graft for TBI healing.

Open Reduction and Internal Fixation with Bone Morphogenetic Protein-2 for Correction of Nonunion Humeral Shaft Fracture with Pseudoarthrosis in the Geriatric Population: A Case Report

Introduction

Bone morphogenic protein-2 (BMP-2) is a potent growth factor cytokine, with indications for interbody spinal fusion surgery and open tibial shaft repairs due to its osteoinductive properties. Off-label usage of BMP-2 has been documented; however, there are limited studies regarding the efficacy of using BMP-2 in non-union humeral shaft fractures.

Case Report

We present a case of a comminuted left humeral shaft fracture with pseudoarthrosis in a 64-year-old woman. Due to the patient's significant comorbidities, initial fracture management focused on non-surgical intervention with the use of a humeral cuff to correct the fracture. However, the patient's report of persistent and significant pain and serial radiographs indicating poor healing with a non-union fracture prompted surgical intervention. The patient underwent an open reduction and internal fixation (ORIF) with the application of one pledget of BMP-2 at the fracture site to promote osteogenesis. To the best of our knowledge, there is limited information about the efficacy of using BMP-2 for humeral fractures.

Conclusion

Six months following the surgery, radiographs have shown appropriate fracture healing of the left humerus without loosening of hardware and other significant complications. The usage of BMP-2 in this patient has shown to be effective in promoting the healing of her nonunion humeral shaft fracture. Although BMP-2 has typically been FDA indicated for use in lumbar interbody spinal fusion surgery and open tibial shaft repairs, this case demonstrates that BMP-2 can also promote healing of non-union humeral shaft fractures in a safe and effective manner.

Nanofibrous 3D scaffolds capable of individually controlled BMP and FGF release for the regulation of bone regeneration

The current clinical applications of bone morphogenetic proteins (BMPs) are limited to only a few specific indications. Locally controlled delivery of combinations of growth factors can be a promising strategy to improve BMP-based bone repair. However, the success of this approach requires the development of an effective release system and the correct choice of growth factors capable of enhancing BMP activity. Basic fibroblast growth factor (bFGF, also known as FGF-2) has shown promise in promoting bone repair, although conflicting results have been reported. Considering the complex biological activities of FGF-2, we hypothesized that FGF-2 can promote BMP-induced bone regeneration only if the dosage and kinetic parameters of the two factors are individually tailored. In this study, we conducted systematic in vitro studies on cell proliferation, differentiation, and mineralization in response to factor dose, delivery mode (sequential or simultaneous), and release rate. Subsequently, we designed individually controlled BMP-7 and FGF-2 release poly(lactide-co-glycolide) (PLGA) nanospheres attached to the poly(l-lactic acid) (PLLA) nanofibrous scaffolds. The data showed that BMP-7-induced bone formation was accelerated by a relatively higher FGF-2 dose (100 ng/scaffold) delivered at a faster release rate, or by a relatively lower FGF-2 dose (10 ng/scaffold) at a slower release rate in an in vivo bone regeneration model. In contrast, a very high dose of FGF-2 (1000 ng/scaffold) inhibited bone regeneration under all conditions. In vitro and in vivo data suggest that FGF-2 improved BMP-7-induced bone regeneration by coordinating FGF-2 dosage and release kinetics to enhance stem cell migration, proliferation, and angiogenesis. STATEMENT OF SIGNIFICANCE: Bone morphogenetic proteins (BMPs) are the most potent growth/differentiation factors in bone development and regeneration. However, the clinical applications of BMPs have been limited to only a few specific indications due to the required supraphysiological dosages with the current BMP products and their side effects. Locally controlled delivery of BMPs and additional growth factors that can enhance their osteogenic potency are highly desired. However, different growth factors act with different mechanisms. Here we report a nanofibrous scaffold that mimics collagen in size and geometry and is immobilized with biodegradable nanospheres to achieve local and distinct release profiles of BMP7 and FGF2. Systematic studies demonstrated low dose BMP7 and FGF2 with different temporal release profiles can optimally enhance bone regeneration.

Mechanisms of Bone Morphogenetic Protein 2 in Respiratory Diseases

PURPOSE OF REVIEW

Bone morphogenetic protein 2 (BMP2) belongs to the transforming growth factor-β (TGF-β) superfamily and plays an important role in regulating embryonic development, angiogenesis, osteogenic differentiation, tissue homeostasis, and cancer invasion. Increasing studies suggest BMP2 is involved in several respiratory diseases. This study aimed to review the role and mechanisms of BMP2 in respiratory diseases.

RECENT FINDINGS

BMP2 signaling pathway includes the canonical and non-canonical signaling pathway. The canonical signaling pathway is the BMP2-SMAD pathway, and the non-canonical signaling pathway includes mitogen-activated protein kinase (MAPK) pathway and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. The BMP2 is related to pulmonary hypertension (PH), lung cancer, pulmonary fibrosis (PF), asthma, and chronic obstructive pulmonary disease (COPD). BMP2 inhibits the proliferation of pulmonary artery smooth muscle cells (PASMCs), promotes the apoptosis of PASMCs to reduce pulmonary vascular remodeling in PH, which is closely related to the canonical and non-canonical pathway. In addition, BMP2 stimulates the proliferation and migration of cells to promote the occurrence, colonization, and metastasis of lung cancer through the canonical and the non-canonical pathway. Meanwhile, BMP2 exert anti-fibrotic function in PF through canonical signaling pathway. Moreover, BMP2 inhibits airway inflammation to maintain airway homeostasis in asthma. However, the signaling pathways involved in asthma are poorly understood. BMP2 inhibits the expression of ciliary protein and promotes squamous metaplasia of airway epithelial cells to accelerate the development of COPD. In conclusion, BMP2 may be a therapeutic target for several respiratory diseases.

Tauroursodeoxycholic acid combined with selenium accelerates bone regeneration in ovariectomized rats

More recently, increased studies have revealed that antioxidants can cure osteoporosis by inhibiting oxidative stress. Tauroursodeoxycholic acid (TUDCA) and Selenium (Se) have been confirmed to possess potent anti-oxidative effects and accelerate bone regeneration. In addition, very little is currently known about the effects of a combination with Se and TUDCA on bone defects in osteoporotic states. We, therefore, aimed to assess the protective effect of combination with Se and TUDCA on bone regeneration and investigate the effect and underlying mechanisms. When MC3T3-E1 was cultured in the presence of H2H2, Se, TUDCA and Se/TUDCA therapy could increase the matrix mineralization and promote expression of anti-oxidative stress markers in MC3T3-E1, while reducing intracellular reactive oxygen species (ROS) and mitochondrial ROS levels. Meanwhile, silent information regulator type 1 (SIRT1) was upregulated in response to Se, TUDCA and Se/TUDCA exposures in H2H2 treated-MC3T3-E1. In the OVX rat model, Se, TUDCA and Se/TUDCA showed a clear positive effect against impaired bone repair in osteoporosis. The results above demonstrate that Se/TUDCA exhibits superior efficacy in both cellular and animal experiments, as compared to Se and TUDCA. In conclusion, combination with Se and TUDCA stimulates bone regeneration and is a promising candidate for promoting bone repair in osteoporosis.

Simulation of the bone remodelling microenvironment by calcium compound-loaded hydrogel fibrous membranes for in situ bone regeneration

The endowment of guided bone regeneration (GBR) membranes with the ability to activate the endogenous regenerative capability of bone to regenerate bone defects is of clinical significance. Herein we explored the preparation of the calcium compound (CC) (calcium sulfate (CaSL), calcium hydrophosphate (CaHP), or tricalcium phosphate (TCaP)) loaded ultrathin silk fibroin (SF)/gelatin (G) fibre membranes via electrospinning as the GBR membranes to regenerate the calvarial bone defects. The in vitro experiments demonstrated that the CaSL-loaded ultrathin fibrous membranes could simulate optimally the bone remodelling microenvironment in comparison with the CaHP- and TCaP-loaded fibrous membranes, displaying the highest activity to regulate the migration, proliferation, and differentiation of mesenchymal stem cells (MSCs). Also, the in vivo experiments demonstrated that the CaSL-loaded fibrous membranes presented the highest intrinsic osteoinduction to guide in situ regeneration of bone. Furthermore, the in vivo experiments demonstrated that the as-prepared composite fibrous membranes possessed good degradability. In summary, our results suggested that the CaSL-loaded fibrous membranes with high intrinsic osteoinduction and good degradability have potential to translate into clinical practice.

A systematic scoping review of the latest data on orthobiologics in the surgical treatment of non-union

INTRODUCTION

Recent studies have shown a growing concern regarding the cost-effectiveness and the lack of supporting data for the biologic agents that are being increasingly used in the orthopedic field. Our aim was to conduct a systematic scoping review of recent publications (last five years) on the use of orthobiologics to treat fracture non-union and summarize the latest available data.

PATIENTS AND METHODS

The inclusion criteria for this review were articles published in English, from 2016 to 2022, and focusing on the use of orthobiologics for the surgical treatment of non-union. Searches were conducted in March 2023 using Pubmed/MEDLINE and Embase. Studies on spinal fusion or gene therapy were excluded. Reviews, case reports with five cases or less, conference proceedings, preliminary reports, pediatric or non-human studies were excluded as well.

RESULTS

The search found 1807 articles, 15 were eligible after PRISMA checklist and exclusions. The evidence was heterogenous and there was only one level II RCT. Recent data suggests that bone morphogenic protein (BMP-2) products could be effective for septic and aseptic tibial non-unions. However, the evidence was not conclusive regarding BMP-7, plasma rich platelets (PRP), stem cells or demineralized bone matrix (DBM).

DISCUSSION

Every non-union case is different in terms of bone defect, biology, mechanical stability, surgical technique and host factors, which contributes to the conflicting reports on the efficacy of orthobiologics in the literature. We might never see a level 1, high powered and robust study defining the efficacy, safety profile and cost-effectiveness of such products.

LEVEL OF EVIDENCE

IV.

In vivo Assessment of AMP2, a Novel Ceramic-Binding BMP-2, in Ovine Lumbar Interbody Fusion

STUDY DESIGN

Assessment of bone formation in an ovine interbody fusion study.

OBJECTIVE

To compare OsteoAdapt SP, which consists of AMP-2, a modified variant of recombinant human bone morphogenetic protein (rhBMP-2) bound to a tricalcium phosphate-containing carrier, to autologous iliac crest bone graft (ICBG) in a lumbar interbody fusion model.

SUMMARY OF BACKGROUND DATA

Treatment of lumbar disk degeneration often involves spinal fusion to reduce pain and motion at the affected spinal segment by insertion of a cage containing bone graft material. Three graft materials were compared in this study-ICBG and OsteoAdapt SP (low or high dose).

METHODS

The sheep underwent lateral lumbar fusion surgery with PEEK or Titanium interbody cages packed with OsteoAdapt SP (low or high dose) or ICBG. Outcomes were evaluated at 8-, 16- and 26- weeks. Newly formed bone quality, bone mineralization, and fusion were assessed by manual palpation, qualitative and semi-quantitative histopathology, histomorphometry, computed tomography (CT), and micro-CT (mCT) analysis.

RESULTS

OsteoAdapt SP was implanted into 43 animals and ICBG into 21 animals (L3-L4). No group showed evidence of systemic toxicity by multiple assessments. All levels were fused by manual palpation at 26 weeks. Serial CT scans showed increasing fusion scores over time. Both doses of OsteoAdapt SP resulted in robust new bone formation and progression of fusion in the interbody cage. Range of motion tests for treatment groups was lower compared with ICBG at 8- and 16 weeks. Similarly, histology at eight weeks demonstrated more robust new bone formation for both OsteoAdapt SP groups compared to autograft.

CONCLUSION

We have demonstrated the preclinical safety and efficacy of OsteoAdapt SP in a clinically relevant large animal model, supporting faster and more robust new bone formation within the interbody cage, comparable to or better than the gold standard, ICBG, in all measures.