Black Phosphorus-Based Dynamic Self-Healing Hydrogel to Integrate Demineralized Bone Matrix and Noggin-Targeting siRNA for Synergistic Osteogenesis

Although a demineralized bone matrix (DBM) is often used as an alternative to an autologous bone graft, its clinical application is still hampered by easy dispersion of DBM particles and insufficient osteoinductivity in the defect site. Herein, we designed a self-healing hydrogel for DBM that can rapidly restore its structural integrity after damage based on amino-rich black phosphorus (BP) nanosheets and aldehyde-functionalized hyaluronic acid (AHA). Given the increased expression of bone morphogenetic protein (BMP) antagonists by DBM stimulation, the osteogenic potency of DBM in the hydrogel carrier was further enhanced by abrogating the BMP antagonism. The BP/AHA hydrogel provided dynamic polymer-nanosheet networks that combine injectability, modability, and physical stability with high DBM loading, where the BP nanosheets served as osteogenic cross-linkers to promote biomineralization and deliver siRNA to suppress undesirable expression of BMP antagonist noggin by DBM. As a result, the BP/AHA hydrogel integrated with DBM and noggin-targeting siRNA synergistically promoted osteogenic differentiation of mesenchymal stem cells by enhancing BMP/Smad signaling. This work demonstrates a promising strategy to improve the efficacy of bone regeneration using bone graft.

Self-Assembled Nanocomposite Hydrogels as Carriers for Demineralized Bone Matrix Particles and Enhanced Bone Repair

Demineralized bone matrix (DBM) has been widely used as an allogeneic alternative to autologous bone graft for bone repair. However, more extensive use of DBM is limited due to its particulate nature after demineralization and rapid particle dispersion following irrigation, resulting in unpredictable osteoinductivity. Here, a new design of injectable hydrogel carriers for DBM that combine self-healing ability and osteogenic properties based on the self-assembly of guanidinylated hyaluronic acid and silica-rich nanoclays is reported. The nanoclays serve as reversible linkages to form a dynamic hydrogel network with the guanidine moieties on the polymer chains. Gelation kinetics and mechanical properties can be controlled by altering nanoclay content in the hydrogel. The resulting hydrogel exerts self-healing ability due to its dynamic crosslinks and well retains its overall performance with high DBM loading. The hydrogel exhibits great cytocompatibility and osteogenic effects mediated by the nanoclays. In vivo delivery of DBM using the nanocomposite hydrogel further demonstrates robust bone regeneration in a mouse calvarial defect model in comparison to DBM delivered with aqueous HA. This work suggests a promising hydrogel platform for many applications including therapeutic delivery and tissue engineering.

Treatment of a Large Tibial Non-Union Bone Defect in a Cat Using Xenograft with Canine-Derived Cancellous Bone, Demineralized Bone Matrix, and Autograft

A 17-month-old domestic short-hair cat was referred due to a non-union in the left tibia. The initial repair, conducted 3 months prior at another animal hospital, involved an intramedullary (IM) pin and wire to address a comminuted fracture. Unfortunately, the wire knot caused a skin tract, resulting in osteomyelitis. Although the wire knot was removed at that hospital, the draining tract persisted, continuously discharging exudate. Upon evaluation, the first surgery was reassessed and revised, involving the removal of the IM pin and the application of external skeletal fixation alongside an antibiotic susceptibility test. After 118 days post-revision surgery, while some cortical continuity was observed, a significant bone defect persisted, posing a substantial risk of refracture should the implant be removed. A second revision surgery was performed, utilizing a bone plate combined with cancellous bone autograft, recombinant human bone morphogenetic protein-2, and xenograft featuring a canine-derived cancellous chip mixed with demineralized bone matrix. Remarkably, the bone completed its healing within 105 days following the subsequent surgery. Radiography demonstrated successful management of the large bone defect up to the 2-year postoperative check-up. During telephone follow-ups for 3.5 years after surgery, no complications were identified, and the subject maintained a favorable gait.

Comparison of Fusion Rates among Various Demineralized Bone Matrices in Posterior Lumbar Interbody Fusion

Background and Objectives: Posterior lumbar interbody fusion (PLIF) plays a crucial role in addressing various spinal disorders. The success of PLIF is contingent upon achieving bone fusion, as failure can lead to adverse clinical outcomes. Demineralized bone matrix (DBM) has emerged as a promising solution for promoting fusion due to its unique combination of osteoinductive and osteoconductive properties. This study aims to compare the effectiveness of three distinct DBMs (Exfuse®, Bongener®, and Bonfuse®) in achieving fusion rates in PLIF surgery. Materials and Methods: A retrospective review was conducted on 236 consecutive patients undergoing PLIF between September 2016 and February 2019. Patients over 50 years old with degenerative lumbar disease, receiving DBM, and following up for more than 12 months after surgery were included. Fusion was evaluated using the Bridwell grading system. Bridwell grades 1 and 2 were defined as 'fusion', while grades 3 and 4 were considered 'non-fusion.' Clinical outcomes were assessed using visual analog scale (VAS) scores for pain, the Oswestry disability index (ODI), and the European quality of life-5 (EQ-5D). Results: Fusion rates were 88.3% for Exfuse, 94.3% for Bongener, and 87.7% for Bonfuse, with no significant differences. All groups exhibited significant improvement in clinical outcomes at 12 months after surgery, but no significant differences were observed among the three groups. Conclusions: There were no significant differences in fusion rates and clinical outcomes among Exfuse, Bongener, and Bonfuse in PLIF surgery.

Complications With Demineralized Bone Matrix, Hydroxyapatite and Beta-Tricalcium Phosphate in Single and Two-Level Anterior Cervical Discectomy and Fusion Surgery

STUDY DESIGN

Systematic literature review.

OBJECTIVES

To analyze the evidence available reporting complications in single or two-level anterior cervical discectomy and fusion (ACDF) using a demineralized bone matrix (DBM), hydroxyapatite (HA), or beta-tricalcium phosphate (β-TCP).

METHODS

A systematic review of the literature using PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov databases was performed in August 2020 to identify studies reporting complications in one or two-level ACDF surgery using DBM, HA, or β-TCP. The study was reported following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines.

RESULTS

A total of 1857 patients were included, 981 male and 876 female, across 17 articles; 5 prospective, and 12 retrospectives. We noted heterogeneity among the included studies concerning the study design and combination of graft materials utilized in them. However, we noted a higher incidence of adjacent segment disease (17.7%) and pseudoarthrosis (9.3%) in fusion constructs using DBM. Studies using β-TCP reported a higher incidence of pseudoarthrosis (28.2%) and implant failures (17.9%).

CONCLUSIONS

Degenerative cervical conditions treated with one or two-level ACDF surgery using DBM, HA, or β-TCP with or without cervical plating are associated with complications such as adjacent segment disease, dysphagia, and pseudarthrosis. However, consequent to the study designs and clinical heterogeneity of the studies, it is not possible to correlate these complications accurately with any specific graft material employed. Further well-designed prospective studies are needed to correctly know the related morbidity of each graft used for achieving fusion in ACDF.

The Use of Osteobiologics in Single versus Multi-Level Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic literature review.

OBJECTIVES

In this study we assessed evidence for the use of osteobiologics in single vs multi-level anterior cervical discectomy and fusion (ACDF) in patients with cervical spine degeneration. The primary objective was to compare fusion rates after single and multi-level surgery with different osteobiologics. Secondary objectives were to compare differences in patient reported outcome measures (PROMs) and complications.

METHODS

After a global team of reviewers was selected, a systematic review using different repositories was performed, confirming to PRISMA and GRADE guidelines. In total 1206 articles were identified and after applying inclusion and exclusion criteria, 11 articles were eligible for analysis. Extracted data included fusion rates, definition of fusion, patient reported outcome measures, types of osteobiologics used, complications, adverse events and revisions.

RESULTS

Fusion rates ranged from 87.7% to 100% for bone morphogenetic protein 2 (BMP-2) and 88.6% to 94.7% for demineralized bone matrix, while fusion rates reported for other osteobiologics were lower. All included studies showed PROMs improved significantly for each osteobiologic. However, no differences were reported when comparing osteobiologics, or when comparing single vs multi-level surgery specifically.

CONCLUSION

The highest fusion rates after 2-level ACDF for cervical spine degeneration were reported when BMP-2 was used. However, PROMs did not differ between the different osteobiologics. Further blinded randomized trials should be performed to compare the use of BMP-2 in single vs multi-level ACDF specifically.

Composite Remineralization of Bone-Collagen Matrices by Low-Temperature Ceramics and Serum Albumin: A New Approach to the Creation of Highly Effective Osteoplastic Materials

This study examined the effectiveness of coating demineralized bone matrix (DBM) with amorphous calcium phosphate (DBM + CaP), as well as a composite of DBM, calcium phosphate, and serum albumin (DBM + CaP + BSA). The intact structure of DBM promotes the transformation of amorphous calcium phosphate (CaP) into dicalcium phosphate dihydrate (DCPD) with a characteristic plate shape and particle size of 5-35 µm. The inclusion of BSA in the coating resulted in a better and more uniform distribution of CaP on the surface of DBM trabeculae. MG63 cells showed that both the obtained forms of CaP and its complex with BSA did not exhibit cytotoxicity up to a concentration of 10 mg/mL in vitro. Ectopic (subcutaneous) implantation in rats revealed pronounced biocompatibility, as well as strong osteoconductive, osteoinductive, and osteogenic effects for both DBM + CaP and DBM + CaP + BSA, but more pronounced effects for DBM + CaP + BSA. In addition, for the DBM + CaP + BSA samples, there was a pronounced full physiological intrafibrillar biomineralization and proangiogenic effect with the formation of bone-morrow-like niches, accompanied by pronounced processes of intramedullary hematopoiesis, indicating a powerful osteogenic effect of this composite.

Enhanced osteogenicity of the demineralized bone-dermal matrix composite by the optimal partial demineralization for sustained release of bioactive molecules

Allogenic demineralized bone matrix (DBM), processed to expose bioactive proteins imbedded by calcium salts, is widely used for bone repair and regeneration as an alternative to the autologous bone graft. However, demineralized bone matrices from tissue banks vary significantly in residual calcium content and osteogenicity for clinical bone regeneration. The present study produced DBM with various residual calcium contents by partial demineralization using ethylenediaminetetraacetic acid disodium (EDTA) and hydrochloric acid. Compositional analysis reveals that, as the percent weight loss of bone materials increases from 0% to 74.9% during demineralization, the residual calcium content of DBM decreases from 24.8% to 0.2% and collagen content increases from 29.7% to 92.6%. Calorimetrical analysis and Fourier transform infrared (FTIR) analysis demonstrated that demineralization to the residual calcium content of <4% enables the complete exposure and/or release of bone collagen fibers and other bioactive molecules. In order to evaluate the relationship between the extent of demineralization and the osteogenicity of DBM, DBM particles were fabricated with the aid of acellular dermal matrix (ADM) microfibers to form flexible foam-like DBM/ADM composites. Proteomic analysis identified various type collagens and bone formation-related bioactive molecules in both ADM and DBM. Using the rat bilateral Φ = 5 mm calvarium defect repair model, the study had shown that the DBM/ADM composite with ~20% DBM residual calcium (e.g., ~40% calcium being removed) maximized the osteogenicity for bone defect repair after 4 and 8 weeks. DBM with ~40% calcium removal had the maximal osteogenicity presumably through the sustained release of bioactive molecules during the process of bone regeneration.

Demineralized Bone Matrix and Fibers in Spinal Fusion

Formation of bony fusion after arthrodesis depends on osteoinduction, osteoconduction, and osteogenesis. Traditionally, the patient's own bone, or autograft, has been used to provide biological material necessary for these steps. However, the amount of autograft obtainable is often inadequate. Modern spine surgery has adopted the use of many autograft extenders or replacements, such as demineralized bone matrix or fibers. The present article covers the history of bone grafting, the production and technical details of demineralized bone matrix, and the evidence supporting its use in spine fusions.

Development of photoreactive demineralized bone matrix 3D printing colloidal inks for bone tissue engineering

Demineralized bone matrix (DBM) has been widely used clinically for dental, craniofacial and skeletal bone repair, as an osteoinductive and osteoconductive material. 3D printing (3DP) enables the creation of bone tissue engineering scaffolds with complex geometries and porosity. Photoreactive methacryloylated gelatin nanoparticles (GNP-MAs) 3DP inks have been developed, which display gel-like behavior for high print fidelity and are capable of post-printing photocrosslinking for control of scaffold swelling and degradation. Here, novel DBM nanoparticles (DBM-NPs, ∼400 nm) were fabricated and characterized prior to incorporation in 3DP inks. The objectives of this study were to determine how these DBM-NPs would influence the printability of composite colloidal 3DP inks, assess the impact of ultraviolet (UV) crosslinking on 3DP scaffold swelling and degradation and evaluate the osteogenic potential of DBM-NP-containing composite colloidal scaffolds. The addition of methacryloylated DBM-NPs (DBM-NP-MAs) to composite colloidal inks (100:0, 95:5 and 75:25 GNP-MA:DBM-NP-MA) did not significantly impact the rheological properties associated with printability, such as viscosity and shear recovery or photocrosslinking. UV crosslinking with a UV dosage of 3 J/cm2 directly impacted the rate of 3DP scaffold swelling for all GNP-MA:DBM-NP-MA ratios with an ∼40% greater increase in scaffold area and pore area in uncrosslinked versus photocrosslinked scaffolds over 21 days in phosphate-buffered saline (PBS). Likewise, degradation (hydrolytic and enzymatic) over 21 days for all DBM-NP-MA content groups was significantly decreased, ∼45% less in PBS and collagenase-containing PBS, in UV-crosslinked versus uncrosslinked groups. The incorporation of DBM-NP-MAs into scaffolds decreased mass loss compared to GNP-MA-only scaffolds during collagenase degradation. An in vitro osteogenic study with bone marrow-derived mesenchymal stem cells demonstrated osteoconductive properties of 3DP scaffolds for the DBM-NP-MA contents examined. The creation of photoreactive DBM-NP-MAs and their application in 3DP provide a platform for the development of ECM-derived colloidal materials and tailored control of biochemical cue presentation with broad tissue engineering applications.

Hybrid Implants Based on Calcium-Magnesium Silicate Ceramic Diopside as a Carrier of Recombinant BMP-2 and Demineralized Bone Matrix as a Scaffold: Ectopic Osteogenesis in Intramuscular Implantation in Mice

High efficiency of hybrid implants based on calcium-magnesium silicate ceramic, diopside, as a carrier of recombinant BMP-2 and xenogenic demineralized bone matrix (DBM) as a scaffold for bone tissue regeneration was demonstrated previously using the model of critical size cranial defects in mice. In order to investigate the possibility of using these implants for growing autologous bone tissue using in vivo bioreactor principle in the patient's own body, effectiveness of ectopic osteogenesis induced by them in intramuscular implantation in mice was studied. At the dose of 7 μg of BMP-2 per implant, dense agglomeration of cells, probably skeletal muscle satellite precursor cells, was observed one week after implantation with areas of intense chondrogenesis, initial stage of indirect osteogenesis, around the implants. After 12 weeks, a dense bone capsule of trabecular structure was formed covered with periosteum and mature bone marrow located in the spaces between the trabeculae. The capsule volume was about 8-10 times the volume of the original implant. There were practically no signs of inflammation and foreign body reaction. Microcomputed tomography data showed significant increase of the relative bone volume, number of trabeculae, and bone tissue density in the group of mice with BMP-2-containing implant in comparison with the group without BMP-2. Considering that DBM can be obtained in practically unlimited quantities with required size and shape, and that BMP-2 is obtained by synthesis in E. coli cells and is relatively inexpensive, further development of the in vivo bioreactor model based on the hybrid implants constructed from BMP-2, diopside, and xenogenic DBM seems promising.

Clinical and Radiographic Evaluation of Autologous Platelet-Rich Fibrin With or Without Demineralized Bone Matrix in the Treatment of Grade II Furcation Defects

Introduction This study aims to differentiate the employment of demineralized bone matrix (DMBM; Osseograft, Advanced Biotech Products (P) Ltd, Chennai, India) and platelet-rich fibrin (PRF) alone to a composite graft consisting of both materials in the surgical actions toward the anomalies of the human periodontal furcation imperfection. Methods In a split-mouth study, 30 patients with mandibular molars affected by the furcation were allocated without conscious choice to test (PRF + DMBM, n = 30) or control (PRF, n = 30) categories. At the starting point, three months after surgery, and six months later, the following modifiable factors were evaluated: probing pocket depth (PPD), full-mouth plaque scores, full-mouth gingival scores, radiographic defect depth, relative vertical clinical attachment level (RVCAL), and relative horizontal clinical attachment level (RHCAL). Results Results at three and six months demonstrated substantial differences between baseline values for both treatment methods in clinical and X-ray imaging appraisal. Nonetheless, the PRF/DMBM group manifests statistically significantly soaring changes observed in comparison to the PRF group. Overall, the probing depth (PD) in the test site was significantly lower than that in the control site, showing a reduction of 68% (95% CI=41%, 95%, p<0.001). Conclusion Clinical indications significantly improved with PRF and DMBM combined instead of PRF alone. On radiographs, the test group also showed higher bone fill.

[Preparation and bone repair capability of a new plastic bone filler material]

Objective

To prepare a new plastic bone filler material with adhesive carrier and matrix particles derived from human bone, and evaluate its safety and osteoinductive ability through animal tests.

Methods

The human long bones donated voluntarily were prepared into decalcified bone matrix (DBM) by crushing, cleaning, and demineralization, and then the DBM was prepared into bone matrix gelatin (BMG) by warm bath method, and the BMG and DBM were mixed to prepare the experimental group's plastic bone filler material; DBM was used as control group. Fifteen healthy male thymus-free nude mice aged 6-9 weeks were used to prepare intermuscular space between gluteus medius and gluteus maximus muscles, and all of them were implanted with experimental group materials. The animals were sacrificed at 1, 4, and 6 weeks after operation, and the ectopic osteogenic effect was evaluated by HE staining. Eight 9-month-old Japanese large-ear rabbits were selected to prepare 6-mm-diameter defects at the condyles of both hind legs, and the left and right sides were filled with the materials of the experimental group and the control group respectively. The animals were sacrificed at 12 and 26 weeks after operation, and the effect of bone defect repair were evaluated by Micro-CT and HE staining.

Results

In ectopic osteogenesis experiment, HE staining showed that a large number of chondrocytes could be observed at 1 week after operation, and obvious newly formed cartilage tissue could be observed at 4 and 6 weeks after operation. For the rabbit condyle bone filling experiment, HE staining showed that at 12 weeks after operation, part of the materials were absorbed, and new cartilage could be observed in both experimental and control groups; at 26 weeks after operation, the most of the materials were absorbed, and large amount of new bone could be observed in the 2 groups, while new bone unit structure could be observed in the experimental group. Micro-CT observation showed that the bone formation rate and area of the experimental group were better than those of the control group. The measurement of bone morphometric parameters showed that the parameters at 26 weeks after operation in both groups were significantly higher than those at 12 weeks after operation ( P<0.05). At 12 weeks after operation, the bone mineral density and bone volume fraction in the experimental group were significantly higher than those in the control group ( P<0.05), and there was no significant difference between the two groups in trabecular thickness ( P>0.05). At 26 weeks after operation, the bone mineral density of the experimental group was significantly higher than that of the control group ( P<0.05). There was no significant difference in bone volume fraction and trabecular thickness between the two groups ( P>0.05).

Conclusion

The new plastic bone filler material is an excellent bone filler material with good biosafety and osteoinductive activity.

Hybrid Implants Based on Calcium-Magnesium Silicate Ceramics Diopside as a Carrier of Recombinant BMP-2 and Demineralized Bone Matrix as a Scaffold: Dynamics of Reparative Osteogenesis in a Mouse Craniotomy Model

Calcium-magnesium silicate ceramics, diopside, is a promising material for use in bone plastics, but until now the possibility of its use as a carrier of recombinant bone morphogenetic protein-2 (BMP-2) has not been studied, as well as the features of reparative osteogenesis mediated by the materials based on diopside with BMP-2. Powder of calcium-magnesium silicate ceramics was obtained by solid-state synthesis using biowaste - rice husks and egg shells - as source components. Main phase of the obtained ceramics was diopside. The obtained particles were irregularly shaped with an average size of about 2.3 μm and ~20% porosity; average pore size was about 24 nm, which allowed the material to be classified as mesoporous. Diopside powder adsorbs more than 150 μg of recombinant BMP-2 per milligram, which exceeds binding capacity of hydroxyapatite, a calcium-phosphate ceramic often used in hybrid implants, by more than 3 times. In vitro release kinetics of BMP-2 was characterized by a burst release in the first 2 days and a sustained release of approximately 0.4 to 0.5% of the loaded protein over the following 7 days. In vivo experiments were performed with a mouse model of cranial defects of critical size with implantation of a suspension of diopside powder with/without BMP-2 in hyaluronic acid incorporated into the disks of demineralized bone matrix with 73-90% volume porosity and macropore size from 50 to 650 μm. Dynamics of neoosteogenesis and bone tissue remodeling was investigated histologically at the time points of 12, 21, 48, and 63 days. Diopside particles were evenly spread in the matrix and caused minimal foreign body reaction. In the presence of BMP-2 by the day 63 significant foci of newly formed bone tissue were formed in the implant pores with bone marrow areas, moreover, large areas of demineralized bone matrix in the implant center and maternal bone at the edges were involved in the remodeling. Diopside could be considered as a promising material for introduction into hybrid implants as an effective carrier of BMP-2.

Surgical Management of Jones Fractures in Athletes: Orthobiologic Augmentation: A Systematic Review and Meta-analysis of 718 Fractures

BACKGROUND

The use of orthobiologics is expanding. However, the use of orthobiologic augmentation in primary fracture fixation surgery remains limited. Primary fracture fixation of the fifth metatarsal (Jones) in athletes is one of the rare situations where primary orthobiologic augmentation has been advocated.

PURPOSE

To determine the effect of orthobiologic augmentation on the outcome of surgically managed Jones fractures in athletes.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, 2 independent team members searched several databases including PubMed, MEDLINE, Embase, Google Scholar, Web of Science, Cochrane Library, and ClinicalTrials.gov through March 2021 to identify studies reporting on surgically managed Jones fractures of the fifth metatarsal exclusively in athletes. The primary outcomes were the return to play (RTP) rate and time to RTP, whereas the secondary outcomes were time to union, union rate, and refractures. Data were presented by type of treatment (biologically augmented fixation or fixation alone).

RESULTS

In the biologically augmented fixation group, successful RTP was reported in 195 (98.98%) of 197 fractures (odds ratio [OR], 97.5%; 95% CI, 95.8%-100%; I² = 0), with a mean time to RTP of 10.3 weeks (95% CI, 9.5-11.1 weeks; I² = 99%). In the group that received fixation without biological augmentation, successful RTP was reported in 516 (99.04%) of 521 fractures (OR, 98.7%; 95% CI, 97.8%-99.7%; I² = 0], with a mean time to RTP of 9.7 weeks (95% CI, 7.84-11.53 weeks; I² = 98.64%]. In the biologically augmented fixation group, fracture union was achieved in 194 (98.48%) of 197 fractures (OR, 97.6%; 95% CI, 95.5%-99.7%; I² = 0%), with a mean time to fracture union of 9.28 weeks (95% CI, 7.23-11.34 weeks; I² = 98.18%). In the group that received fixation without biological augmentation, fracture union was achieved in 407 (93.78%) of 434 fractures (OR, 97.4%; 95% CI, 96%-98.9%; I² = 0%), with a mean time to fracture union of 8.57 weeks (95% CI, 6.82-10.32 weeks; I² = 98.81%).

CONCLUSION

Orthobiologically augmented surgical fixation of Jones fractures in athletes is becoming increasingly common, despite the lack of comparative studies to support this practice. Biologically augmented fixation of Jones fractures results in higher fracture union rates than fixation alone but similar rates of RTP and time to RTP. Although the current evidence recommends primary surgical fixation for the management of Jones fractures in athletes, further high quality comparative studies are required to establish the indication for orthobiologic augmentation.

Clinical Outcomes following Biologically Enhanced Demineralized Bone Matrix Augmentation of Complex Rotator Cuff Repair

Complex rotator cuff tears provide a significant challenge for treating surgeons, given their high failure rate following repair and the associated morbidity. The purpose of this study is to evaluate the clinical outcomes of patients who underwent biologically enhanced demineralized bone matrix augmentation of rotator cuff repairs. Twenty patients with complex rotator cuff tears underwent arthroscopic rotator cuff repair by a single surgeon with demineralized bone matrix (DBM) augmentation that was biologically enhanced with platelet-rich plasma and concentrated bone marrow aspirate. Post-operative MRI was used to determine surgical success. Patient reported outcome measures and range of motion data were collected pre-operatively and at the final post-operative visit for each patient. Ten patients (50%) with DBM augmentation of their arthroscopic rotator cuff repair were deemed non-failures. The failure group had less improvement of visual analogue pain scale (p = 0.017), Simple Shoulder Test (p = 0.032), Single Assessment Numerical Evaluation (p = 0.006) and abduction (p = 0.046). There was no difference between the groups for change in American Shoulder and Elbow Society score (p = 0.096), Constant-Murley score (p = 0.086), forward elevation (p = 0.191) or external rotation (p = 0.333). The present study found that 50% of patients who underwent biologically enhanced DBM augmentation of their rotator cuff repair demonstrated MRI-determined failure of supraspinatus healing.

Preclinical Safety of a 3D-Printed Hydroxyapatite-Demineralized Bone Matrix Scaffold for Spinal Fusion

STUDY DESIGN

Prospective, randomized, controlled preclinical study.

OBJECTIVE

The objective of this study was to compare the host inflammatory response of our previously described hyperelastic, 3D-printed (3DP) hydroxyapatite (HA)-demineralized bone matrix (DBM) composite scaffold to the response elicited with the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) in a preclinical rat posterolateral lumbar fusion model.

SUMMARY OF BACKGROUND DATA

Our group previously found that this 3D-printed HA-DBM composite material shows promise as a bone graft substitute in a preclinical rodent model, but its safety profile had yet to be assessed.

METHODS

Sixty female Sprague-Dawley rats underwent bilateral posterolateral intertransverse lumbar spinal fusion using with the following implants: 1) type I absorbable collagen sponge (ACS) alone; 2) 10 μg rhBMP-2/ACS; or 3) the 3DP HA-DBM composite scaffold (n = 20). The host inflammatory response was assessed using magnetic resonance imaging, while the local and circulating cytokine expression levels were evaluated by enzyme-linked immunosorbent assays at subsequent postoperative time points (N = 5/time point).

RESULTS

At both 2 and 5 days postoperatively, treatment with the HA-DBM scaffold produced significantly less soft tissue edema at the fusion bed site relative to rhBMP-2-treated animals as quantified on magnetic resonance imaging. At every postoperative time point evaluated, the level of soft tissue edema in HA-DBM-treated animals was comparable to that of the ACS control group. At 2 days postoperatively, serum concentrations of tumor necrosis factor-α and macrophage chemoattractant protein-1 were significantly elevated in the rhBMP-2 treatment group relative to ACS controls, whereas these cytokines were not elevated in the HA-DBM-treated animals.

CONCLUSION

The 3D-printed HA-DBM composite induces a significantly reduced host inflammatory response in a preclinical spinal fusion model relative to rhBMP-2.Level of Evidence: N/A.

Demineralized bone matrix combined with cytotoxic T-lymphocyte-associated protein 4 promotes osteogenic differentiation of human bone marrow mesenchymal stem cells and suppresses the activation of T lymphocytes in vitro

Cytotoxic T-lymphocyte-associated protein 4 (CTLA4) can promote osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMMSCs), and CTLA4-modified bone marrow mesenchymal stem cells possess immunoregulatory effects. In the present study, we aimed to construct a new tissue engineering bone using demineralized bone matrix and CTLA4 protein, designated as DBM-CTLA4 (+). The effects of DBM-CTLA4 (+) on the osteogenic differentiation of hBMMSCs and T lymphocyte activation were evaluated through in vitro experiments. The cumulative release of CTLA4 from DBM-CTLA4 (+) was determined using enzyme-linked immunosorbent assay. DBM-CTLA4 (+) was co-cultured in a Transwell chamber with either phytohemagglutinin-treated hBMMSCs or human peripheral blood mononuclear cells (hPBMCs). Osteogenic differentiation of hBMMSCs was assessed by calcium deposition, ALP activity, and the protein levels of COL1A1, RUNX2, BMP2, and OPN. T lymphocyte activity was assessed by measuring the protein levels of IL-2, L-17, HLA-DRA1, IFN-γ, and RANKL. Our results showed that the cumulative release rates of CTLA4 at 7, 14, 21, and 28 days were 12.6% ± 1.4%, 30.2% ± 2.3%, 49.8% ± 3.8%, and 60.5% ± 2.7%, respectively. Compared to the negative control, DBM-CTLA4 (+) promoted the proliferation of hBMMSCs, and enhanced calcium deposition, ALP activity, and protein levels of COL1A1, RUNX2, BMP2, and OPN. Moreover, DBM-CTLA4 (+) decreased the levels of IL-2, IL-17, HLA-DR, IFN-γ, and RANKL in hPBMCs treated with phytohemagglutinin. In conclusion, DBM-CTLA4 (+) promoted proliferation and osteogenic differentiation of hBMMSCs and suppressed T lymphocyte activation.

[Performance evaluation of two antigen-extracted xenogeneic ostein and experimental study on repairing skull defects in rats]

Objective

To evaluate the physical and chemical properties, immunogenicity, and osteogenesis of two antigen-extracted xenogeneic bone scaffolds-decalcified bone matrix (DBM) and calcined bone.

Methods

By removing the inorganic and organic components of adult pig femus, xenogeneic DBM and calcined bone were prepared respectively. The density and pH value of the two materials were measured and calculated, the material morphology and pore diameter were observed by scanning electron microscope, and the surface contact angle was measured by automatic contact angle measuring instrument. The safety, osteogenic activity, and immunogenicity of the two materials were evaluated by cytotoxicity test, osteoblast proliferation test, DNA residue test, and human peripheral blood lymphocyte proliferation test. The two materials were implanted into the 5 mm full-thickness skull defect of 6-week-old male Sprague Dawley rats (the blank control group was not implanted with materials). The materials were taken at 4 and 8 weeks after operation, the repair effect of the materials on the rat skull was observed and evaluated by gross observation, Micro-CT scanning, and HE staining observation.

Results

Compared with calcined bone, DBM has lower density and poor hydrophilicity; the pH value of the two materials was 5.5-6.1, and the pore diameter was 160-800 μm. The two materials were non-cytotoxic and could promote the proliferation of osteoblasts. The absorbance ( A) values of osteoblast proliferation at 1, 4, and 7 days in the DBM group were significantly higher than those in the calcined bone group ( P<0.05). The DNA residues of the two materials were much lower than 50 ng/mg dry weight, and neither of them could stimulate the proliferation and differentiation of human peripheral blood lymphocytes. The results of animal experiments in vivo showed that the bone volume/total volume (BV/TV) in DBM group and calcined bone group were significantly higher than that in blank control group at 4 weeks after operation ( P<0.05), and that in calcined bone group was significantly higher than that in DBM group ( P<0.05); at 8 weeks after operation, there was no significant difference in BV/TV between groups ( P>0.05). HE staining showed that at 4 and 8 weeks after operation, the defect in the blank control group was filled with fibrous connective tissue, the defect was obvious, and no bone growth was found; the defect in DBM group and calcined bone group had been repaired to varying degrees, and a large number of new bone formation could be seen. The material degradability of DBM group was better than that of calcined bone group.

Conclusion

The physical and chemical properties and degradability of the two kinds of xenogeneic bone scaffolds were slightly different, both of them have no immunogenicity and can promote the repair and reconstruction of skull defects in rats.

Preparation and Characterization of Moldable Demineralized Bone Matrix/Calcium Sulfate Composite Bone Graft Materials

Demineralized bone matrix (DBM) is a decalcified allo/xenograft retaining collagen and noncollagenous proteins, which has been extensively used because of its osteoconductive and osteoinductive properties. Calcium sulfate (CaSO₄, CS) is a synthetic bone substitute used in bone healing with biocompatible, nontoxic, bioabsorbable, osteoconductive, and good mechanical characteristics. This study aims to prepare a DBM/CS composite bone graft material in a moldable putty form without compromising the peculiar properties of DBM and CS. For this purpose, firstly, porcine femur was defatted using chloroform/methanol and extracted by acid for demineralization, then freeze-dried and milled/sieved to obtain DBM powder. Secondly, the α-form and β-form of calcium sulfate hemihydrate (CaSO₄·0.5H₂O, CSH) were produced by heating gypsum (CaSO₄·2H₂O). The morphology and particle sizes of α- and β-CSH were obtained by SEM, and their chemical properties were confirmed by EDS, FTIR and XRD. Furthermore, the DBM-based graft was mixed with α- or β-CSH at a ratio of 9:1, and glycerol/4% HPMC was added as a carrier to produce a putty. DBM/CSH putty possesses a low washout rate, good mechanical strength and biocompatibility. In conclusion, we believe that the moldable DBM/CSH composite putty developed in this study could be a promising substitute for the currently available bone grafts, and might have practical application in the orthopedics field as a potential bone void filler.

Efficacy, Cost, and Complications of Demineralized Bone Matrix in Instrumented Lumbar Fusion: Comparison With rhBMP-2

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To evaluate demineralized bone matrix as an adjunct for instrumented lumbar spine fusion compared with recombinant human bone morphogenetic protein-2 (rhBMP-2).

METHODS

Clinical and radiographic review was performed of 43 patients with degenerative spine disease treated with posterolateral spinal fusion with or without posterior or transforaminal lumbar interbody fusion. Final analysis included sixteen patients treated with demineralized bone matrix (DBM; Accell Evo3, SeaSpine) compared with a retrospective matched group of 21 patients treated with rhBMP-2 (rhBMP-2, Infuse, Medtronic). All patients were followed for 24 months. Fusion was evaluated by computed tomography and/or x-ray. Clinical outcomes included visual analogue scale (VAS), Oswestry Disability Index (ODI), and Short Form 12 (SF-12).

RESULTS

Overall fusion rate, including posterolateral and/or interbody fusion, was 100% for both groups, though the fusion rates in the posterolateral space alone were 93.5% and 100% for the DBM and rhBMP-2 groups, respectively. Clinical outcomes were similar between groups, with the DBM group showing greater improvement in ODI. The rhBMP-2 group showed higher rates of radiographic complications with 7 of 21 patients (33.3%) demonstrating either adjacent level fusion or ectopic bone formation, compared with zero in the DBM group. Average biologic cost per level was $1522 for DBM and $3505 for rhBMP-2.

CONCLUSIONS

DBM and rhBMP-2 demonstrated similar radiographic and clinical outcomes in instrumented lumbar fusions. rhBMP-2 was associated with higher rates of radiographic complications and significantly higher costs.

Minimally invasive treatment of long bone non-unions with bone marrow concentrate, demineralized bone matrix and platelet-rich fibrin in 38 patients

To determine the efficacy of percutaneous injection of autologous bone marrow concentrated (BMC), demineralized bone matrix (DBM), and platelet rich fibrin (PRF) in the treatment of long bone non-unions. From January 2011 to January 2018 patients with non-union of the lower limbs who were on the waiting list for open grafting with established tibial or femoral non-union and minimal deformity were eligible to participate in this study. Patients were treated with a single percutaneous injection of DBM, BMC and PRF. Our study group comprised 38 patients (26 males and 12 females; mean age 39, range 18 to 65). Non-unions were located in the femur (18 cases) and in the tibia (20 cases). Clinical and imaging follow-up ranged from 4 to 60 months (mean 20 months). Bone union occurred in 30 out of 38 patients (79%) in an average of 7 months (range 3 to 12) and all healed patients had full weight bearing after 9 months on average (range 6 to 12) from injection. In 19 cases the osteosynthesis was removed 12 months on average (range 3 to 36) from surgery. One patient developed infection at the non-union site after treatment. Percutaneous injection of DBM, BMC, and PRF is an effective treatment for long-bone non-unions. This technique allows the bone to heal with a minimally invasive approach and with a hospitalization of 2 days. Key elements of bone regeneration consist of a combination of biological and biomechanical therapeutic approach.

Comparative Assessment of Autogenous Cancellous Bone Graft and Bovine-Derived Demineralized Bone Matrix for Secondary Alveolar Bone Grafting in Patients With Unilateral Cleft Lip and Palate

OBJECTIVE

Comparison between bovine-derived demineralized bone matrix (DMBM) and iliac crest graft over long term for secondary alveolar bone grafting (SABG) in patients with unilateral cleft lip and palate (UCLP) in terms of radiological and clinical outcomes.

DESIGN

Prospective, randomized, parallel groups, double-blind, controlled trial.

SETTING

Unit of Oral and Maxillofacial Surgery, Oral Health Science Centre, Postgraduate Institute of Medical Education & Research, Chandigarh.

PARTICIPANTS

Twenty patients with UCLP.

INTERVENTIONS

Patients were allocated into group I (Iliac crest bone graft) and group II (DMBM) for SABG. Outcomes were assessed at 2 weeks, 6 months, and then after mean follow-up period of 63 months.

OUTCOMES MEASURES

Volumetric analysis of the grafted bone in the alveolar cleft site was done through cone beam computed tomography using Cavalieri principle and modified assessment tool. Clinical assessment was performed in terms of pain, swelling, duration of hospital stay, cost of surgery, alar base symmetry, and donor site morbidity associated with iliac crest harvesting.

RESULTS

Volumetric analysis through Cavalieri principle revealed comparable bone uptake at follow-up of 6 months between group I (70%) and group II (69%). Modified assessment tool showed no significant difference between horizontal and vertical bone scores over short- and long-term follow-up. In group II, there was higher cost of surgery, but no donor site morbidity unlike group I.

CONCLUSIONS

Demineralized bone matrix proved analogous to iliac crest bone graft as per volumetric analysis over shorter period. However, although statistically insignificant, net bone volume achieved was lower than the iliac crest graft at longer follow-up.

Is percutaneous injection of bone marrow concentrate, demineralized bone matrix and PRF an alternative to curettage and bone grafting for treating aneurysmal bone cyst?

To determine the efficacy and safety of a single injection with autologous bone marrow concentrate (BMC) combined with demineralized bone matrix (DBM) and platelet-rich fibrin (PRF) compared to curettage and bone grafting for treating aneurysmal bone cysts (ABC). Two hundred thirty-nine patients were treated with curettage and bone grafting (Curettage Group), and 21 with percutaneous injection of DBM associated with autologous BMC and PRF (DBM + BMC + PRF Group). All patients attended the outpatient clinic to assess ABC healing and clinical results at the first 3, 6, 9 and 18 months after surgery and then annually in the absence of symptoms. The mean follow-up was 42 months for the Curettage Group (range 6-180 months) and 28 months for the DBM + BMC + PRF Group (range, 6-85 months). Out of the 21 patients who had injection with BMC, DBM, and PRF, 17 (80%) require no additional treatment and they were considered healed. Of the 239 patients treated with curettage and bone grafting after core needle or open biopsy, 177 (74%) were considered healed after the first treatment. Injection in comparison with curettage presented the same risk for local recurrence. The overall rate of local recurrence for all patients was 25%. Univariate and multivariate analyses showed a significant difference in local recurrence rates in patients younger than 15 years, and for the cyst located in the long bones of the lower limbs than the cyst located in the long bones of the upper limbs.

TGF-β Activity of a Demineralized Bone Matrix

Allografts consisting of demineralized bone matrix (DBM) are supposed to retain the growth factors of native bone. However, it is not clear if transforming growth factor β1 (TGF-β1) is maintained in the acid-extracted human bone. To this aim, the aqueous solutions of supernatants and acid lysates of OraGRAFT^® Demineralized Cortical Particulate and OraGRAFT^® Prime were prepared. Exposing fibroblasts to the aqueous solution caused a TGF-β receptor type I kinase-inhibitor SB431542-dependent increase in interleukin 11 (IL11), NADPH oxidase 4 (NOX4), and proteoglycan 4 (PRG4) expression. Interleukin 11 expression and the presence of TGF-β1 in the aqueous solutions were confirmed by immunoassay. Immunofluorescence further confirmed the nuclear translocation of Smad2/3 when fibroblasts were exposed to the aqueous solutions of both allografts. Moreover, allografts released matrix metalloprotease-2 activity and blocking proteases diminished the cellular TGF-β response to the supernatant. These results suggest that TGF-β is preserved upon the processing of OraGRAFT^® and released by proteolytic activity into the aqueous solution.

PEGylated Coating Affects DBM Osteoinductivity In Vivo by Changing Inflammatory Responses

PEGylation is a widely used modification in device coating or drug delivery by combing materials with poly(ethylene glycol) (PEG). In the present study, a well-established rat ectopic bone formation model was used to elucidate how PEGylated coating affects demineralized bone matrix (DBM) osteoinductivity in vivo by changing the inflammation events at the early phase of implantation. A range of cell-matrix interactions was characterized at the cellular and functional levels, including growth factor activity and kinetics, immune cell migration and activation, and bone formation in vivo. After 28 days, DBM's bone formation potential decreased in groups with increasing PEG concentration in the gelatin carrier. The increasing PEG concentration did not affect DBM's osteoinductive growth factor release or activity. However, increasing PEG cross-linking concentration resulted in decreased DBM-related early phase inflammatory reactions, reduced neutrophil infiltration, decreased coating material degradation, lowered the total number and active mast cells, and decreased CD80+ macrophage expression. Understanding and controlling cell-material responses may improve the design and development of functional medical devices.

In Vitro and In Vivo Study of a Novel Nanoscale Demineralized Bone Matrix Coated PCL/β-TCP Scaffold for Bone Regeneration

Bone defects remains a challenge for surgeons. Bone graft scaffold can fill the defect and enhance the bone regeneration. Demineralized bone matrix (DBM) is an allogeneic bone graft substitute, which can only be used as a filling material rather than a structural bone graft. Coating of the scaffolds with nanoscale DBM may enhance the osteoinductivity or osteoconductivity. Herein the lyophilization method is presented to coat the nano-DBM on surface of the porous polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) scaffolds fabricated by 3D printing technology. The morphology, elastic modulus, in vitro cell biocompatibility, and in vivo performance are investigated. Scanning electron microscope (SEM) shows DBM particle clusters with size of 200-500 nm are observed on scaffolds fibers after coating. MC3T3-E1 cells on nano-DBM coated PCL/β-TCP scaffold show better activity than on PCL/β-TCP scaffold. In vivo tests show better infiltration of new bone tissue in nano-DBM coated PCL/β-TCP scaffold than PCL/β-TCP scaffold via the interface. These results show the presence of nano-DBM coating on PCL/β-TCP scaffold could enhance the attachment, proliferation, and viability of cells and benefit for the new bone formation surrounding and deep inside the scaffolds. Nano-DBM could potentially be used as a new kind of biomaterial for bone defect treatment.

[Effect of demineralized bone matrix modified by laminin α4 chain functional peptide on H-type angiogenesis and osteogenesis to promote bone defect repair]

Objective

Based on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis.

Methods

Functional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group ( n=12) and DBM group ( n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67].

Results

Material related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly ( t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD ( P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM ( P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity ( P<0.05), and the number of CD31 ^hiEmcn ^hi cells increased significantly ( P<0.05).

Conclusion

DBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.

Plasma Cell Proliferation Is Reduced in Myeloma-Induced Hypercalcemia and in Co-Culture with Normal Healthy BM-MSCs

OBJECTIVE

In multiple myeloma (MM), stimulation of osteoclasts and bone marrow (BM) lesions lead to hypercalcemia, renal failure, and anemia. Co-culture of the myeloma cells in both hypocalcemia and hypercalcemia concentrations with bone marrow-mesenchymal stem cells were evaluated.

MATERIALS AND METHODS

Viability and survival of myeloma cells were assessed by microculture tetrazolium test and flow cytometric assays. Mesenchymal stem cells (MSCs) were extracted from normal and myeloma patients and were co-cultured with myeloma cells.

RESULTS

Myeloma cells showed less survival in both hypocalcaemia and hypercalcemia conditions (P <.01). The paracrine and juxtacrine conditions of demineralized bone matrix-induced hypercalcemia increased the proliferation and survival of the cells (P <.05). Unlike myeloma MSCs, normal MSCs reduced the survival of and induced apoptosis in myeloma cells (P <.1).

CONCLUSION

Normal healthy-MSCs do not protect myeloma cells, but inhibit them. However, increasing the ratio of myeloma cells to MSCs reduces their inhibitory effects of MSCs and leads to their myelomatous transformation.

First Human Leucocyte Antigen (HLA) Response and Safety Evaluation of Fibrous Demineralized Bone Matrix in a Critical Size Femoral Defect Model of the Sprague-Dawley Rat

Treatment of large bone defects is one of the great challenges in contemporary orthopedic and traumatic surgery. Grafts are necessary to support bone healing. A well-established allograft is demineralized bone matrix (DBM) prepared from donated human bone tissue. In this study, a fibrous demineralized bone matrix (f-DBM) with a high surface-to-volume ratio has been analyzed for toxicity and immunogenicity. f-DBM was transplanted to a 5-mm, plate-stabilized, femoral critical-size-bone-defect in Sprague-Dawley (SD)-rats. Healthy animals were used as controls. After two months histology, hematological analyses, immunogenicity as well as serum biochemistry were performed. Evaluation of free radical release and hematological and biochemical analyses showed no significant differences between the control group and recipients of f-DBM. Histologically, there was no evidence of damage to liver and kidney and good bone healing was observed in the f-DBM group. Reactivity against human HLA class I and class II antigens was detected with mostly low fluorescence values both in the serum of untreated and treated animals, reflecting rather a background reaction. Taken together, these results provide evidence for no systemic toxicity and the first proof of no basic immunogenic reaction to bone allograft and no sensitization of the recipient.

Supramolecular Hydrogels Based on Nanoclay and Guanidine-Rich Chitosan: Injectable and Moldable Osteoinductive Carriers

Supramolecular hydrogels have great potential as biomaterials for tissue engineering applications or vehicles for delivering therapeutic agents. Herein, a self-healing and pro-osteogenic hydrogel system is developed based on the self-assembly of laponite nanosheets and guanidinylated chitosan, where laponite works as a physical crosslinker with osteoinductive properties to form a network structure with a cationic guanidine group on chitosan chains. The hydrogels can be prepared with varying ratios of chitosan to laponite and display self-healing and injectable properties because of supramolecular forces as well as osteoinductive activity due to nanoclay. They enhance cell adhesion and promote osteogenic differentiation of mesenchymal stem cells by activating the Wnt/β-catenin signaling pathway. In addition, the hydrogel is used as a malleable carrier for the demineralized bone matrix (DBM). The loading of the DBM does not affect the self-healing and injectable natures of hydrogels while enhancing the osteogenic capacity, indicating that advanced allograft bone formulations with carriers can facilitate handling and bone healing. This work provides the first demonstration of therapeutic supramolecular design for the treatment of bone defects.

Influence of Geometry and Architecture on the In Vivo Success of 3D-Printed Scaffolds for Spinal Fusion

We previously developed a recombinant growth factor-free, three-dimensional (3D)-printed material comprising hydroxyapatite (HA) and demineralized bone matrix (DBM) for bone regeneration. This material has demonstrated the capacity to promote re-mineralization of the DBM particles within the scaffold struts and shows potential to promote successful spine fusion. Here, we investigate the role of geometry and architecture in osteointegration, vascularization, and facilitation of spine fusion in a preclinical model. Inks containing HA and DBM particles in a poly(lactide-co-glycolide) elastomer were 3D-printed into scaffolds with varying relative strut angles (90° vs. 45° advancing angle), macropore size (0 μm vs. 500 μm vs. 1000 μm), and strut alignment (aligned vs. offset). The following configurations were compared with scaffolds containing no macropores: 90°/500 μm/aligned, 45°/500 μm/aligned, 90°/1000 μm/aligned, 45°/1000 μm/aligned, 90°/1000 μm/offset, and 45°/1000 μm/offset. Eighty-four female Sprague-Dawley rats underwent spine fusion with bilateral placement of the various scaffold configurations (n = 12/configuration). Osteointegration and vascularization were assessed by using microComputed Tomography and histology, and spine fusion was assessed via blinded manual palpation. The 45°/1000 μm scaffolds with aligned struts achieved the highest average fusion score (1.61/2) as well as the highest osteointegration score. Both the 45°/1000 μm/aligned and 90°/1000 μm/aligned scaffolds elicited fusion rates of 100%, which was significantly greater than the 45°/500 μm/aligned iteration (p < 0.05). All porous scaffolds were fully vascularized, with blood vessels present in every macropore. Vessels were also observed extending from the native transverse process bone, through the protrusions of new bone, and into the macropores of the scaffolds. When viewed independently, scaffolds printed with relative strut angles of 45° and 90° each allowed for osteointegration sufficient to stabilize the spine at L4-L5. Within those parameters, a pore size of 500 μm or greater was generally sufficient to achieve unilateral fusion. However, our results suggest that scaffolds printed with the larger pore size and with aligned struts at an advancing angle of 45° may represent the optimal configuration to maximize osteointegration and fusion capacity. Overall, this work suggests that the HA/DBM composite scaffolds provide a conducive environment for bone regeneration as well as vascular infiltration. This technology, therefore, represents a novel, growth-factor-free biomaterial with significant potential as a bone graft substitute for use in spinal surgery. Impact statement We previously developed a recombinant growth factor-free, three-dimensional (3D)-printed composite material comprising hydroxyapatite and demineralized bone matrix for bone regeneration. Here, we identify a range of 3D geometric and architectural parameters that support the preclinical success of the scaffold, including efficient vascularization, osteointegration, and, ultimately, spinal fusion. Our results suggest that this material holds great promise as a clinically translatable biomaterial for use as a bone graft substitute in orthopedic procedures requiring bone regeneration.

In-vivo Performance of Seven Commercially Available Demineralized Bone Matrix Fiber and Putty Products in a Rat Posterolateral Fusion Model

Introduction: Demineralized bone matrix (DBM) is a widely used bone graft in spinal fusion. Most commercial DBMs are composed of demineralized bone particles (~125–800 microns) suspended in a carrier that provides improved handling but dilutes the osteoinductive component. DBM fibers (DBF) provide improved osteoconductivity and do not require a carrier. It has been suggested that 100% DBF may offer improved performance over particulate-based DBMs with carrier.

Study Design: Seven commercially available DBM products were tested in an athymic rat posterolateral fusion model. There were four 100% DBFs, two DBFs containing a carrier, and one particulate-based DBM containing carrier.

Objective: The study objectives were to evaluate the in vivo performance: (1) compare fusion rate and fusion maturity of six commercially available DBFs and one particulate-based DBM, and (2) assess the effect of carrier on fusion outcomes for DBFs in a posterolateral fusion model.

Methods: The DBF/DBM products evaluated were: Strand^TM Family, Propel® DBM Fibers, Vesuvius® Demineralized Fibers, Optium® DBM Putty, Grafton® DBF, Grafton Flex, and DBX® Putty. Single-level posterolateral fusion was performed in 69 athymic rats. Fusion was assessed bilaterally after 4 weeks by manual palpation, radiograph and CT for bridging bone. Fusion mass maturity was assessed with a CT maturity grading scale and by histology. Statistical analysis was performed using Fishers Exact Test for categorical data and Kruskal-Wallis Test for non-parametric data.

Results: Strand Family achieved 100% fusion (18/18) by manual palpation, radiographic and CT evaluation, significantly higher than Propel Fibers, Vesuvius Fibers, Optium Putty, and DBX Putty, and not statistically higher than Grafton DBF and Grafton Flex. Strand Family provided the highest fusion maturity, with CT maturity grade of 2.3/3.0 and 89% mature fusion rate. Fusion results suggest a detrimental effect of carrier on fusion performance.

Conclusions: There were large variations in fusion performance for seven commercially available DBM products in an established preclinical fusion model. There were even significant differences between different 100% DBF products, suggesting that composition alone does not guarantee in vivo performance. In the absence of definitive clinical evidence, surgeons should carefully consider available data in valid animal models when selecting demineralized allograft options.

3D-Printed Ceramic-Demineralized Bone Matrix Hyperelastic Bone Composite Scaffolds for Spinal Fusion

Although numerous spinal biologics are commercially available, a cost-effective and safe bone graft substitute material for spine fusion has yet to be proven. In this study, "3D-Paints" containing varying volumetric ratios of hydroxyapatite (HA) and human demineralized bone matrix (DBM) in a poly(lactide-co-glycolide) elastomer were three-dimensional (3D) printed into scaffolds to promote osteointegration in rats, with an end goal of spine fusion without the need for recombinant growth factor. Spine fusion was evaluated by manual palpation, and osteointegration and de novo bone formation within scaffold struts were evaluated by laboratory and synchrotron microcomputed tomography and histology. The 3:1 HA:DBM composite achieved the highest mean fusion score and fusion rate (92%), which was significantly greater than the 3D printed DBM-only scaffold (42%). New bone was identified extending from the host transverse processes into the scaffold macropores, and osteointegration scores correlated with successful fusion. Strikingly, the combination of HA and DBM resulted in the growth of bone-like spicules within the DBM particles inside scaffold struts. These spicules were not observed in DBM-only scaffolds, suggesting that de novo spicule formation requires both HA and DBM. Collectively, our work suggests that this recombinant growth factor-free composite shows promise to overcome the limitations of currently used bone graft substitutes for spine fusion. Impact Statement Currently, there exists a no safe, yet highly effective, bone graft substitute that is well accepted for use in spine fusion procedures. With this work, we show that a three-dimensional printed scaffold containing osteoconductive hydroxyapatite and osteoinductive demineralized bone matrix that promotes new bone spicule formation, osteointegration, and successful fusion (stabilization) when implemented in a preclinical model of spine fusion. Our study suggests that this material shows promise as a recombinant growth factor-free bone graft substitute that could safely promote high rates of successful fusion and improve patient care.

Graft Materials and Biologics for Spinal Interbody Fusion

Spinal fusion is the most widely performed procedure in spine surgery. It is the preferred treatment for a wide variety of pathologies including degenerative disc disease, spondylolisthesis, segmental instability, and deformity. Surgeons have the choice of fusing vertebrae by utilizing cages containing autografts, allografts, demineralized bone matrices (DBMs), or graft substitutes such as ceramic scaffolds. Autografts from the iliac spine are the most commonly used as they offer osteogenic, osteoinductive, and osteoconductive capabilities, all while avoiding immune system rejection. Allografts obtained from cadavers and living donors can also be advantageous as they lack the need for graft extraction from the patient. DBMs are acid-extracted organic allografts with osteoinductive properties. Ceramic grafts containing hydroxyapatite can be readily manufactured and are able to provide osteoinductive support while having a long shelf life. Further, bone-morphogenetic proteins (BMPs), mesenchymal stem cells (MSCs), synthetic peptides, and autologous growth factors are currently being optimized to assist in improving vertebral fusion. Genetic therapies utilizing viral transduction are also currently being devised. This review provides an overview of the advantages, disadvantages, and future directions of currently available graft materials. The current literature on growth factors, stem cells, and genetic therapy is also discussed.

Biomimetic open porous structured core-shell microtissue with enhanced mechanical properties for bottom-up bone tissue engineering

Background: Microtissues constructed with hydrogels promote cell expansion and specific differentiation by mimicking the microarchitecture of native tissues. However, the suboptimal mechanical property and osteogenic activity of microtissues fabricated by natural polymers need further improvement for bone reconstruction application. Core-shell designed structures are composed of an inner core part and an outer part shell, combining the characteristics of different materials, which improve the mechanical property of microtissues. Methods: A micro-stencil array chip was used to fabricate an open porous core-shell micro-scaffold consisting of gelatin as shell and demineralized bone matrix particles modified with bone morphogenetic protein-2 (BMP-2) as core. Single gelatin micro-scaffold was fabricated as a control. Rat bone marrow mesenchymal stem cells (BMSCs) were seeded on the micro-scaffolds, after which they were dynamic cultured and osteo-induced in mini-capsule bioreactors to fabricate microtissues. The physical characteristics, biocompatibility, osteo-inducing and controlled release ability of the core-shell microtissue were evaluated in vitro respectively. Then microtissues were tested in vivo via ectopic implantation and orthotopic bone implantation in rat model. Results: The Young's modulus of core-shell micro-scaffold was nearly triple that of gelatin micro-scaffold, which means the core-shell micro-scaffolds have better mechanical property. BMSCs rapidly proliferated and retained the highest viability on core-shell microtissues. The improved osteogenic potential of core-shell microtissues was evidenced by the increased calcification based on von kossa staining and osteo-relative gene expression. At 3months after transplantation, core-shell microtissue group formed the highest number of mineralized tissues in rat ectopic subcutaneous model, and displayed the largest amount of new bony tissue deposition in rat orthotopic cranial defect. Conclusion: The novel core-shell microtissue construction strategy developed may become a promising cell delivery platform for bone regeneration.

Impact of Gentamicin-Loaded Bone Graft on Defect Healing in a Sheep Model

Infections of bone are severe complications, and an optimization of grafting material with antimicrobial drugs might be useful for prevention and treatment. This study aimed to investigate the influence of gentamicin-loaded bone graft on the healing of bone defects in a sheep model. Metaphyseal and diaphyseal drill hole defects (diameter: 6 mm, depth: 15 mm) were filled with graft or gentamicin-loaded graft (50 mg/g graft) or were left untreated. Analysis of regeneration after three and nine weeks, micro-computed tomography (μCT), and histology revealed a significant increase in bone formation in the drill hole defects, which began at the edges of the holes and grew over time into the defect center. The amount of graft decreased over time due to active resorption by osteoclasts, while osteoblasts formed new bone. No difference between the groups was seen after three weeks. After nine weeks, significantly less mineralized tissue was formed in the gentamicin-loaded graft group. Signs of inflammatory reactions were seen in all three groups. Even though the applied gentamicin concentration was based on the concentration of gentamicin mixed with cement, the healing process was impaired. When using local gentamicin, a dose-dependent, compromising effect on bone healing should be considered.

Escherichia coli BMP-2 showed comparable osteoinductivity with Chinese hamster ovary derived BMP-2 with demineralized bone matrix as carrier

Escherichia coli bone morphogenetic protein-2 (ErhBMP-2) had a larger yield but less osteoinductivity than Chinese hamster ovary cell bone morphogenetic protein-2 (CrhBMP-2). Since the release profile of rhBMP-2 affects its osteoinductivity, an appropriate carrier could improve the effect of ErhBMP-2. Demineralized bone matrix (DBM) was one of the most widely used bone substitutes, but few studies evaluated the osteoinductivity of ErhBMP-2 while it was carried by DBM. Therefore, we compared the osteoinductivity of ErhBMP-2 with CrhBMP-2 with DBM as the carrier of each. In vitro results showed ErhBMP-2 had slightly less osteoinductivity than CrhBMP-2. However, with DBM as the carrier, ErhBMP-2 induced significantly more bone regeneration in rat calvaria defects. Therefore, ErhBMP-2 might have comparable osteoinductivity with CrhBMP-2 while carried by DBM.

Current Updates on Bone Grafting Biomaterials and Recombinant Human Growth Factors Implanted Biotherapy for Spinal Fusion: A Review of Human Clinical Studies

BACKGROUND

Owing to their great promise in the spinal surgeries, bone graft substitutes have been widely investigated for their safety and clinical potential. By the current advances in the spinal surgery, an understanding of the precise biological mechanism of each bone graft substitute is mandatory for upholding the induction of solid spinal fusion.

OBJECTIVE

The aim of the present review is to critically discuss various surgical implications and level of evidence of most commonly employed bone graft substitutes for spinal fusion.

METHOD

Data was collected via electronic search using "PubMed", "SciFinder", "ScienceDirect", "Google Scholar", "Web of Science" and a library search for articles published in peer-reviewed journals, conferences, and e-books.

RESULTS

Despite having exceptional inherent osteogenic, osteoinductive, and osteoconductive features, clinical acceptability of autografts (patient's own bone) is limited due to several perioperative and postoperative complications i.e., donor-site morbidities and limited graft supply. Alternatively, allografts (bone harvested from cadaver) have shown great promise in achieving acceptable bone fusion rate while alleviating the donor-site morbidities associated with implantation of autografts. As an adjuvant to allograft, demineralized bone matrix (DBM) has shown remarkable efficacy of bone fusion, when employed as graft extender or graft enhancer. Recent advances in recombinant technologies have made it possible to implant growth and differentiation factors (bone morphogenetic proteins) for spinal fusion.

CONCLUSION

Selection of a particular bone grafting biotherapy can be rationalized based on the level of spine fusion, clinical experience and preference of orthopaedic surgeon, and prevalence of donor-site morbidities.

Budget impact analysis of demineralized bone matrix in combination with autograft in lumbar spinal fusion procedures for the treatment of lumbar degenerative disc disease in Spain

OBJECTIVE

To estimate the budget impact (BI) of introducing local autograft (LA) combined with demineralized bone matrix (LA + DBM) in lumbar spinal fusion (LSF) procedures to treat lumbar degenerative disc disease (LDDD) in Spain.

METHODS

A decision tree model was developed to evaluate the 4-year BI associated with introducing LA + DBM putty to replace currently available grafting methods, including iliac crest bone graft (ICBG), LA alone, and LA combined with beta-tricalcium phosphate (LA + ceramics), with 30%, 40%, and 30% market shares, respectively. The analysis was conducted for a hypothetical cohort of 100 patients with LDDD receiving LSF, assuming LA + DBM would replace 100% of the standard of care mix. The fusion rates extracted from the literature were validated by an expert panel. Costs (€2017) were obtained from different Spanish sources. Budget impact and incremental cost per successful fusion were calculated from the perspective of the Spanish National Health System (NHS).

RESULTS

Over 4 years, replacing currently available options with LA + DBM for 100 patients resulted in an additional cost of €12,330 (€123/patient), and an additional 14 successful fusions, implying a cost of €881 per additional successful fusion. When costs of productivity loss were included, the introduction of LA + DBM resulted in cost savings of €70,294 (€703/patient).

LIMITATIONS

The lack of high-quality, homogeneous, head-to-head research studying the efficacy of grafting procedures available to patients undergoing LSF, in addition to a lack of long-term follow-up in existing studies. Therefore, the number of fusions occurring within the model's time horizon may be underestimated.

CONCLUSIONS

Acquisition costs of DBM were partially offset by costs of failed fusions, adverse events and reoperation when switching 100 hypothetical LDDD patients undergoing LSF procedures from standard of care grafting methods to LA + DBM from the perspective of the Spanish NHS. DBM cost was entirely offset when costs of lost productivity were considered.

Demineralized Bone Matrix Coating Si-Ca-P Ceramic Does Not Improve the Osseointegration of the Scaffold

The aim of this study was to manufacture and evaluate the effect of a biphasic calcium silicophosphate (CSP) scaffold ceramic, coated with a natural demineralized bone matrix (DBM), to evaluate the efficiency of this novel ceramic material in bone regeneration. The DBM-coated CSP ceramic was made by coating a CSP scaffold with gel DBM, produced by the partial sintering of different-sized porous granules. These scaffolds were used to reconstruct defects in rabbit tibiae, where CSP scaffolds acted as the control material. Micro-CT and histological analyses were performed to evaluate new bone formation at 1, 3, and 5 months post-surgery. The present research results showed a correlation among the data obtained by micro-CT and the histomorphological results, the gradual disintegration of the biomaterial, and the presence of free scaffold fragments dispersed inside the medullary cavity occupied by hematopoietic bone marrow over the 5-month study period. No difference was found between the DBM-coated and uncoated implants. The new bone tissue inside the implants increased with implantation time. Slightly less new bone formation was observed in the DBM-coated samples, but it was not statistically significant. Both the DBM-coated and the CSP scaffolds gave excellent bone tissue responses and good osteoconductivity.

Nonunion fracture healing: Evaluation of effectiveness of demineralized bone matrix and mesenchymal stem cells in a novel sheep bone nonunion model

Nonunion treatment has a high rate of success, although recalcitrant nonunion may determine the need for amputation. Therefore, new treatment options are continuously investigated in order to further reduce the risk of nonunion recurrence. This study aimed to (a) develop a new large animal model for bone atrophic nonunion and (b) compare the efficacy of demineralized bone matrix (DBM) and DBM in combination with mesenchymal stem cells (MSC) in the new nonunion model. The new model consists of a noncritical, full-thickness segmental defect created in the sheep tibia, stabilized by an intramedullary nail, and involves the creation of a locally impaired blood supply achieved through periosteum excision and electrocauterization of the stump ends. Six weeks after defect creation, lack of hard tissue callus and established nonunion was observed in all operated tibiae both by radiographic and clinical evaluation. Nonunion was treated with allogeneic DBM or autologous MSC cultivated on DBM particles (DBM + MSC) for 1 day before implantation. Twelve weeks after treatment, radiographic, microtomographic, histologic, and histomorphometric analysis showed the formation of bone callus in DBM group, whereas the fracture healing appeared at an early stage in DBM + MSC group. Torsional strength and stiffness of the DBM group appeared higher than those of DBM + MSC group, although the differences were not statistically significant. In conclusion, a new sheep bone nonunion model resembling the complexity of the clinical condition was developed. DBM is an effective option for nonunion treatment, whereas MSC do not improve the healing process when cultivated on DBM particles before implantation.

Evaluation of Mesenchymal Stem Cell Sheets Overexpressing BMP-7 in Canine Critical-Sized Bone Defects

The aim of this study was to investigate the in vitro osteogenic capacity of bone morphogenetic protein 7 (BMP-7) overexpressing adipose-derived (Ad-) mesenchymal stem cells (MSCs) sheets (BMP-7-CS). In addition, BMP-7-CS were transplanted into critical-sized bone defects and osteogenesis was assessed. BMP-7 gene expressing lentivirus particles were transduced into Ad-MSCs. BMP-7, at the mRNA and protein level, was up-regulated in BMP-7-MSCs compared to expression in Ad-MSCs. Osteogenic and vascular-related gene expressions were up-regulated in BMP-7-CS compared to Ad-MSCs and Ad-MSC sheets. In a segmental bone-defect model, newly formed bone and neovascularization were enhanced with BMP-7-CS, or with a combination of BMP-7-CS and demineralized bone matrix (DBM), compared to those in control groups. These results demonstrate that lentiviral-mediated gene transfer of BMP-7 into Ad-MSCs allows for stable BMP-7 production. BMP-7-CS displayed higher osteogenic capacity than Ad-MSCs and Ad-MSC sheets. In addition, BMP-7-CS combined with demineralized bone matrix (DBM) stimulated new bone and blood vessel formation in a canine critical-sized bone defect. The BMP-7-CS not only provides BMP-7 producing MSCs but also produce osteogenic and vascular trophic factors. Thus, BMP-7-CS and DBM have therapeutic potential for the treatment of critical-sized bone defects and could be used to further enhance clinical outcomes during bone-defect treatment.

Demineralized bone matrix-based microcarrier scaffold favors vascularized large bone regeneration in vivo in a rat model

Insufficient neo-vascularization of in vivo implanted cell-seeded scaffold remains a major bottleneck for clinical translation of engineered bone formation. Demineralized bone matrix is an ideal bone scaffold for bone engineering due to its structural and biochemical components similar to those of native bone. We hypothesized that the microcarrier form of demineralized bone matrix favors ingrowth of vessels and bone regeneration upon in vivo implantation. In this study, a rat model of femoral vessel pedicle-based bone engineering was employed by filling the demineralized bone matrix scaffolds inside a silicone chamber that surrounded the vessel pedicles, and to compare the efficiency of vascularized bone regeneration between microcarrier demineralized bone matrix and block demineralized bone matrix. The results showed that bone marrow stem cells better adhered to microcarrier demineralized bone matrix and produced more extracellular matrices during in vitro culture. After in vivo implantation, microcarrier demineralized bone matrix seeded with bone marrow stem cells formed relatively more bone tissue than block demineralized bone matrix counterpart at three months upon histological examination. Furthermore, micro-computed tomography three-dimensional reconstruction showed that microcarrier demineralized bone matrix group regenerate significantly better and more bone tissues than block demineralized bone matrix both qualitatively and quantitatively (p < 0.05). Moreover, micro-computed tomography reconstructed angiographic images also demonstrated significantly enhanced tissue vascularization in microcarrier demineralized bone matrix group than in block demineralized bone matrix group both qualitatively and quantitatively (p < 0.05). Anti-CD31 immunohistochemical staining of (micro-) vessels and semi-quantitative analysis also evidenced enhanced vascularization of regenerated bone in microcarrier demineralized bone matrix group than in block demineralized bone matrix group (p < 0.05). In conclusion, the microcarrier form of demineralized bone matrix is an ideal bone regenerative scaffold due to its advantages of osteoinductivity and vascular induction, two essentials for in vivo bone regeneration.

Allograft Versus Demineralized Bone Matrix in Instrumented and Noninstrumented Lumbar Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

The aim was to determine the fusion efficacy of allograft and demineralized bone matrix (DBM) in lumbar instrumented and noninstrumented fusion procedures for degenerative lumbar disorders.

METHODS

A literature search was conducted using the PubMed and Cochrane databases. To be considered, publications had to meet 4 criteria: patients were treated for a degenerative lumbar disorder, a minimum group size of 10 patients, use of allograft or DBM, and at least a 2-year follow-up. Data on the study population, follow-up time, surgery type, grafting material, fusion rates, and its definition were collected.

RESULTS

The search yielded 692 citations with 17 studies meeting the criteria including 4 retrospective and 13 prospective studies. Six studies used DBM and 11 employed allograft alone or in the combination with autograft. For the allograft, fusion rates ranged from 58% to 68% for noninstrumented and from 68% to 98% for instrumented procedures. For DBM, fusion rates were 83% for noninstrumented and between 60% and 100% for instrumented lumbar fusion procedures.

CONCLUSIONS

Both allograft and DBM appeared to provide similar fusion rates in instrumented fusions. On the other hand, in noninstrumented procedures DBM was superior. However, a large variation in the type of surgery, outcomes collection, lack of control groups, and follow-up time prevented any significant conclusions. Thus, studies comparing the performance of allograft and DBM to adequate controls in large, well-defined patient populations and with a sufficient follow-up time are needed to establish the efficacy of these materials as adjuncts to fusion.

Application of a Demineralized Cortical Bone Matrix and Bone Marrow-Derived Mesenchymal Stem Cells in a Model of Chronic Rotator Cuff Degeneration

BACKGROUND

The success of rotator cuff repair is primarily dependent on tendon-bone healing. Failure is common because weak scar tissue replaces the native enthesis, rendering it prone to reruptures. A demineralized bone matrix (DBM) consists of a network of collagen fibers that provide a sustained release of growth factors such as bone morphogenetic proteins. Previous studies have demonstrated that it can regenerate a fibrocartilaginous enthesis.

HYPOTHESIS

The use of a DBM and mesenchymal stem cells (MSCs) at the healing enthesis will result in a higher bone mineral density at the tendon insertion and will enhance the regeneration of a morphologically superior enthesis when compared with an acellular human dermal matrix.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen female Wistar rats underwent unilateral detachment of the supraspinatus tendon. Three weeks later, tendon repair was carried out in animals randomized into 3 groups: group 1 received augmentation of the repair with a cortical allogenic DBM (n = 6); group 2 received augmentation with a nonmeshed, ultrathick, acellular human dermal matrix (n = 6); and group 3 underwent tendon-bone repair without a scaffold (n = 6). All animals received 1 × 10⁶ MSCs delivered in fibrin glue to the repair site. Specimens were retrieved at 6 weeks postoperatively for histological analysis and the evaluation of bone mineral density.

RESULTS

All groups demonstrated closure of the tendon-bone gap with a fibrocartilaginous enthesis. Although there were no significant differences in the enthesis maturation and modified Movin scores, repair augmented with a dermal matrix + MSCs exhibited a disorganized enthesis, abnormal collagen fiber arrangement, and greater cellularity compared with other MSC groups. Only repairs augmented with a DBM + MSCs reached a bone mineral density not significantly lower than nonoperated controls.

CONCLUSION

A DBM enhanced with MSCs can augment rotator cuff healing at 6 weeks and restore bone mineral density at the enthesis to its preinjury levels.

CLINICAL RELEVANCE

Biological augmentation of rotator cuff repair with a DBM and MSCs may reduce the incidence of retears, although further studies are required to determine its effectiveness.

Synthesis and characterization of polyphosphazene microspheres incorporating demineralized bone matrix scaffolds controlled release of growth factor for chondrogenesis applications

As a promising strategy for the successful regeneration of articular cartilage, tissue engineering has received increasing recognition of control release. Two kinds of functional poly (alanine ethyl ester-co-glycine ethyl ester) phosphazene microspheres with different ratios of side-substituent groups were synthesized by emulsion technique. The rate of degradation/hydrolysis of the polymers was carefully tuned to suit the desired application for control release. For controlled delivery of growth factors, the microspheres overcame most of severe side effects linked to demineralized bone matrix (DBM) scaffolds, which had been previously optimized for cartilage regeneration. The application of scaffolds in chondrogenic differentiation was investigated by subcutaneous implantation in nude mice. In the present study, we have provided a novel microsphere-incorporating demineralized bone matrix (MS/DBM) scaffolds to release transforming growth factor-β1 or insulin-like growth factors-1. Laser confocal fluorescence staining showed that the surface of microspheres was a suitable environment for cell attachment. Histological and immunohistochemical evaluations have shown that significantly more cartilaginous extracellular matrix was detected in MS/DBM group when compared with DBM alone group (P<0.05). In addition, the biomechanical test showed that this composite scaffold exhibited favorable mechanical strength as a delivery platform. In conclusion, we demonstrated that MS/DBM scaffolds was sufficient to support stem bone marrow-derived mesenchymal stem cells chondrogenesis and neo-cartilage formation.

Recombinant Human Bone Morphogenetic Protein-2 (rhBMP-2) with Additional Protein Domain Synthesized in E. coli: In Vivo Osteoinductivity in Experimental Models on Small and Large Laboratory Animals

Recombinant human bone morphogenetic protein-2 with an additional s-tag domain (s-tag-BMP-2) synthesized in E. coli is characterized by higher solubility and activity than the protein without additional s-tag domain, which increases the yield during purification and simplifies protein introduction into the osteoplastic materials. The high osteoinductivity of the demineralized bone matrix with s-tag-BMP-2 was shown on the model of regeneration of cranial defects of a critical size in mice and on the model of implantation of porous titanium matrix into defects of femoral and tibial bones in rabbits.

Demineralized Bone Matrix to Augment Tendon-Bone Healing: A Systematic Review

Background:

Following injury to the rotator cuff and anterior cruciate ligament, a direct enthesis is not regenerated, and healing occurs with biomechanically inferior fibrous tissue. Demineralized bone matrix (DBM) is a collagen scaffold that contains growth factors and is a promising biological material for tendon and ligament repair because it can regenerate a direct fibrocartilaginous insertion via endochondral ossification.

Purpose:

To provide a comprehensive review of the literature investigating the use of DBM to augment tendon-bone healing in tendon repair and anterior cruciate ligament reconstruction (ACLR).

Study Design:

Systematic review.

Methods:

Electronic databases (MEDLINE and EMBASE) were searched for preclinical and clinical studies that evaluated the use of DBM in tendon repair and ACLR. Search terms included the following: (“demineralized bone matrix” OR “demineralized cortical bone”) AND (“tissue scaffold” OR “tissue engineering” OR “ligament” OR “tendon” OR “anterior cruciate ligament” OR “rotator cuff”). Peer-reviewed articles written in English were included, and no date restriction was applied (searches performed February 10, 2017). Methodological quality was assessed with peer-reviewed scoring criteria.

Results:

The search strategy identified 339 articles. After removal of duplicates and screening according to inclusion criteria, 8 studies were included for full review (tendon repair, n = 4; ACLR, n = 4). No human clinical studies were identified. All 8 studies were preclinical animal studies with good methodological quality. Five studies compared DBM augmentation with non-DBM controls, of which 4 (80%) reported positive findings in terms of histological and biomechanical outcomes.

Conclusion:

Preclinical evidence indicates that DBM can improve tendon-bone healing, although clinical studies are lacking. A range of animal models of tendon repair and ACLR showed that DBM can re-create a direct fibrocartilaginous enthesis, although the animal models are not without limitations. Before clinical trials are justified, research is required that determines the best source of DBM (allogenic vs xenogenic) and the best form of DBM (demineralized cortical bone vs DBM paste) to be used in them.

Comparison of three different types of scaffolds preseeded with human bone marrow mononuclear cells on the bone healing in a femoral critical size defect model of the athymic rat

Large bone defects often pose major difficulties in orthopaedic surgery. The application of long-term cultured stem cells combined with a scaffold lead to a significant improvement of bone healing in recent experiments but is strongly restricted by European Union law. Bone marrow mononuclear cells (BMC), however, can be isolated and transplanted within a few hours and have been proven effective in experimental models of bone healing. The effectivity of the BMC-supported therapy might be influenced by the type of scaffold. Hence, we compared three different scaffolds serving as a carrier for BMC in a rat femoral critical size defect with regard to the osteogenic activity in the defect zone. Human demineralized bone matrix (DBM), bovine cancellous bone hydroxyapatite ceramic (BS), or β-tricalcium phosphate (β-TCP) were seeded with human BMC and hereafter implanted into critically sized bone defects of male athymic nude rats. Autologous bone served as a control. Gene activity was measured after 1 week, and bone formation was analysed histologically and radiologically after 8 weeks. Generally, regenerative gene expression (BMP2, RUNX2, VEGF, SDF-1, and RANKL) as well as bony bridging and callus formation was observed to be most pronounced in defects filled with autologous bone, followed in descending order by DBM, β-TCP, and BS. Although DBM was superior in most aspects of bone regeneration analysed in comparison to β-TCP and BS, the level of autologous bone could not be attained.