rhBMP-2 induces terminal differentiation of human bone marrow mesenchymal stromal cells only by synergizing with other signals.

BACKGROUND: Recombinant human bone morphogenetic protein 2 (rhBMP-2) and human bone marrow mesenchymal stromal cells (hBM-MSCs) have been thoroughly studied for research and translational bone regeneration purposes. rhBMP-2 induces bone formation in vivo, and hBM-MSCs are its target, bone-forming cells. In this article, we studied how rhBMP-2 drives the multilineage differentiation of hBM-MSCs both in vivo and in vitro. METHODS: rhBMP-2 and hBM-MSCs were tested in an in vivo subcutaneous implantation model to assess their ability to form mature bone and undergo multilineage differentiation. Then, the hBM-MSCs were treated in vitro with rhBMP-2 for short-term or long-term cell-culture periods, alone or in combination with osteogenic, adipogenic or chondrogenic media, aiming to determine the role of rhBMP-2 in these differentiation processes. RESULTS: The data indicate that hBM-MSCs respond to rhBMP-2 in the short term but fail to differentiate in long-term culture conditions; these cells overexpress the rhBMP-2 target genes DKK1, HEY-1 and SOST osteogenesis inhibitors. However, in combination with other differentiation signals, rhBMP-2 acts as a potentiator of multilineage differentiation, not only of osteogenesis but also of adipogenesis and chondrogenesis, both in vitro and in vivo. CONCLUSIONS: Altogether, our data indicate that rhBMP-2 alone is unable to induce in vitro osteogenic terminal differentiation of hBM-MSCs, but synergizes with other signals to potentiate multiple differentiation phenotypes. Therefore, rhBMP-2 triggers on hBM-MSCs different specific phenotype differentiation depending on the signalling environment.

Addition of recombinant human bone morphogenic protein-2 to the graft materials improves the clinical outcomes of implants placed in grafted maxillary sinus.

Background/purpose: The long-term outcomes of implants placed in grafted sinuses using recombinant human bone morphogenetic protein-2 (rhBMP-2) are unclear. This study aimed to compare 3- and 5-year implant survival rates and marginal bone loss (MBL) during functional loading. Materials and methods: In this retrospective study, we analyzed 63 implants inserted after maxillary sinus floor augmentation (MSFA) in 45 patients between January 2016 and April 2019. The outcome variables were: 1) 3- and 5-year cumulative survival rates of the implants and 2) MBL after functional loading. Other assessed variables included patient demographic information, preoperative residual bone height (RBH), surgical site, implant length and diameter, graft material, healing period before loading, prosthetic type, and opposing dentition. Results: The cumulative 3- and 5-year survival rates of the implants were 100% in the rhBMP-2 group and 95.5% and 86.4% in the non-rhBMP-2 group, respectively. The average 3- and 5-year MBL were 1.14 ± 0.67 mm, 1.30 ± 0.74 mm in the rhBMP-2 group and 1.68 ± 0.90 mm, 2.27 ± 1.29 mm in the non-rhBMP-2 group, respectively. Significant differences were observed between 3 and 5 years between the two groups. Conclusion: Addition of the rhBMP-2 to the graft materials positively affects implant placement in the grafted maxillary sinus in terms of implant survival and MBL when preoperative RBH is unfavorable.

Recombinant Human Peptide Growth Factors, Bone Morphogenetic Protein-7 (rhBMP7), and Platelet-Derived Growth Factor-BB (rhPDGF-BB) for Osteoporosis Treatment in an Oophorectomized Rat Model.

Bone morphogenetic protein (BMP) and platelet-derived growth factor (PDGF) are known to regulate/stimulate osteogenesis, playing vital roles in bone homeostasis, rendering them strong candidates for osteoporosis treatment. We evaluated the effects of recombinant human BMP-7 (rhBMP7) and PDGF-BB (rhPDGF-BB) in an oophorectomy-induced osteoporosis rat model. Forty Sprague Dawley rats underwent oophorectomy surgery; treatments commenced on the 100th day post-surgery when all animals exhibited signs of osteoporosis. These peptide growth factors were administered intraocularly (iv) once or twice a week and the animals were monitored for a total of five weeks. Two weeks after the conclusion of the treatments, the animals were euthanized and tissues were collected for assessment of alkaline phosphatase, X-ray, micro-CT, and histology. The results indicate that the most promising treatments were 20 µg/kg rhPDGF-BB + 30 µg/kg rhBMP-7 twice a week and 30 µg/kg BMP-7 twice a week, showing significant increases of 15% (p < 0.05) and 13% (p < 0.05) in bone volume fraction and 21% (p < 0.05) and 23% (p < 0.05) in trabecular number, respectively. In conclusion, rhPDGF-BB and rhBMP-7 have demonstrated the ability to increase bone volume and density in this osteoporotic animal model, establishing them as potential candidates for osteoporosis treatment.

Evaluation of the Fusion Rate and Safety of Escherichia coli-Derived rhBMP-2 in Transforaminal Lumbar Interbody Fusion for Patients with Degenerative Lumbar Disease: A Prospective, Multicenter, Single-Arm Trial.

Background: Few studies have documented the viability of E. coli-derived recombinant human bone morphogenetic protein-2 (rhBMP-2) in transforaminal lumbar interbody fusion (TLIF). This study aimed to assess the safety and fusion rate of rhBMP-2 in TLIF. Methods: The study was conducted as a prospective, multicenter, single-arm trial, and 30 patients needing one- or two-level TLIF were enrolled. Fusion rate was assessed using the 12-month interbody fusion rate on CT. Postoperative problems, including seroma, radiculitis, and ectopic bone formation, which have been documented as risks associated with rhBMP-2 in prior studies, were recorded. Results: The study demonstrated fusion outcomes in all instances at 52 and 104 weeks post-surgery. Significant improvements were observed in clinical outcomes, with ODI, SF-36, and VAS scores, all achieving statistical significance (p < 0.0001). No perioperative adverse events requiring reoperation were reported, and there were no incidences of seroma, radiculitis, cage migration, grafted bone extrusion, postoperative neurologic deficit, or deep wound infection. Conclusions: The study demonstrates the high safety and efficacy in inducing bone fusion of E. coli-derived rhBMP-2 in TLIF, with a notable absence of adverse postoperative complications. Trial registration: This study protocol was registered at Korea Clinical Research Information Service (number identifier: KCT0004738) on July 2020.

A pilot study: Nano-hydroxyapatite-PEG/PLA containing low dose rhBMP2 stimulates proliferation and osteogenic differentiation of human bone marrow derived mesenchymal stem cells.

Background: Bone morphogenetic protein 2 (BMP2) can enhance posterolateral spinal fusion (PLSF). The minimum effective dose that may stimulate mesenchymal stem cells however remains unknown. Nano-hydroxyapatite (nHAp) polyethylene glycol (PEG)/polylactic acid (PLA) was combined with recombinant human BMP2 (rhBMP2). We in vitro evaluated proliferation, differentiation, and osteogenic genes of human bone marrow mesenchymal stem cells with 0.5, 1.0, and 3.0 µg/mL rhBMP2 doses in this study. Methods: In vitro experimental study was designed to proliferation by a real-time quantitative cell analysis system and the osteogenic differentiation by alkaline phosphatase (ALP) activity and osteogenic marker (Runx2, OPN, and OCN) gene expressions of human derived bone marrow mesenchymal stem cells (hBMMSCs). nHAp was produced by wet chemical process and characterized by Fourier transform infrared spectrophotometer, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. PEG/PLA polymer was produced at a 51:49 molar ratio. 0.5, 1.0, and 3.0 µg/mL rhBMP2 and nHAp was combined with the polymers. hBMMSCs were characterized by multipotency assays and surface markers were assessed by flow cytometer. The hBMMSC-rhBMP2 containing nHAp-PEG/PLA composite interaction was evaluated by transmission electron microscopy. Proliferative effect was evaluated by real-time proliferation analysis, and osteogenic capacity was evaluated by ALP activity assay and qPCR. Results: hBMMSC proliferation in the 0.5 µg/mL rhBMP2 + nHAp-PEG/PLA and the 1.0 µg/mL rhBMP2 + nHAp-PEG/PLA groups were higher compared to control. 1.0 µg/mL rhBMP2 + nHAp-PEG/PLA and 3.0 µg/mL rhBMP2 + nHAp-PEG/PLA containing composites induced ALP activity on days 3 and 10. 0.5 µg/mL rhBMP2 + nHAp-PEG/PLA application stimulated Runx2 and OPN gene expressions. Conclusion: rhBMP2 + nHAp-PEG/PLA composites stimulate hBMMSC proliferation and differentiation. The nHAp-PEG/PLA composite with low dose of rhBMP2 may enhance bone formation in future clinical PLSF applications.

Radiographic and histological evaluation of bone formation induced by rhBMP-2-incorporated biomimetic calcium phosphate material in clinical alveolar sockets preservation.

PURPOSE: We assessed the efficiency of low-dose recombinant human bone morphogenetic protein-2 (rhBMP-2) incorporated biomimetic calcium phosphate on ß-tricalcium phosphate (ß-TCP) (rhBMP-2/BioCaP/ß-TCP) on bone formation in a model of socket preservation using cone beam computed tomography (CBCT) scanning and histological examination. METHODS: Forty patients undergoing minimally invasive single-root tooth extraction for dental implantation were randomized to three groups according to the material used for socket preservation: filling with rhBMP-2/BioCaP/ß-TCP, ß-TCP, or natural healing (kept unfilled) (controls). The alveolar sockets (including the control group) were covered by two-layer collagen membranes and sutured. Two CBCT scans were taken, one immediately after socket preservation procedure (baseline) and another 6 weeks later. Gray values (GVs) obtained from CBCT were recorded. During insertion of the dental implant, biopsies were taken and analyzed histologically for new bone formation, residual material, and unmineralized bone tissue at the core of the biopsy. RESULTS: The mean (± standard deviation) changes of GVs of the CBCT scans at the central area of filled materials were as follows: 373.19 ± 157.16 in the rhBMP-2/BioCaP/ß-TCP group, 112.26 ± 197.25 in the ß-TCP group, and -257 ± 273.51 in the control group. The decrease of GVs in the rhBMP-2/BioCaP/ß-TCP group as compared with the ß-TCP group was statistically significant (P < 0.001). Differences in new bone formation (P = 0.006) were also found: 21,18% ± 7.62% in the rhBMP-2/BioCaP/ß-TCP group, 13.44% ± 6.03% in the ß-TCP group, and 9.49% ± 0.08% in controls. The residual material was10.04% ± 4.57% in the rhBMP-2/BioCaP/ß-TCP group vs. 20.60% ± 9.54%) in the ß-TCP group (P < 0.001). Differences in unmineralized bone tissue (P < 0.001) were also found (68.78% ± 7.67%, 65.96% ± 12.64%, and 90.38% ± 7.5% in the rhBMP-2/BioCaP/ß-TC, ß-TCP, and control groups, respectively). CONCLUSIONS: This study shows that rhBMP-2/BioCaP/ß-TCP is a promising bone substitute with fast degradation and potent pro-osteogenic capacity that can be useful for socket preservation in implant dentistry. TRIAL REGISTRATION: ChiCTR, ChiCTR2000035263. Registered 5 August 2020, https://www.chictr.org.cn/ChiCTR2000035263 .

Treatment of Human Intraosseous Periodontal Defects Using Recombinant Human Bone Morphogenetic Protein-2: A Randomized Controlled Clinical Trial.

Aim The purpose of this research was to assess the clinical and radiographic outcomes of recombinant human bone morphogenetic protein-2 (rhBMP-2) for the treatment of intraosseous abnormalities after periodontal flap surgery. Material and methods Patients aged 35-55 years who had undergone periodontal treatment at Shree Bankey Bihari Dental College and Research Centre, Ghaziabad, and had a total of 14 intraosseous abnormalities were included in the research. Those in the control group had open flap debridement with alloplast, whereas those in the experimental group underwent the same procedure with the addition of rhBMP-2. Clinical indicators, such as plaque index (PI), gingival index, probing pocket depth (PPD), clinical attachment level, and radiographic defect fill, were collected at baseline at three months, six months, and nine months. Results The findings demonstrated that following periodontal treatment, both sets of patients had considerable improvements in their PI, gingival index, and PPD. The degree of relative connection improved significantly in both groups. When comparing the two groups radiographically, we saw that the test group had significantly better defect fill than the control group. Conclusion According to this research, there was a statistically significant decrease in PI, gingival index, PPD, clinical attachment level, and radiographic bone fill in patients who received rhBMP-2. Open flap debridement with rhBMP-2 and alloplastic bone grafts showed better reduction than open flap debridement with alloplastic bone grafts group in the radiographic defect fill.

Application of rhBMP in spinal fusion surgery: any correlation of cancer incidence? A systematic review and meta-analysis.

PURPOSE: Safety concerns regarding the application of bone morphogenetic proteins (BMPs) have been highlighted in recent years. It is noted that both BMP and their receptors being identified as a trigger for cancer growth. Here, we aimed to determine the safety and efficacy of BMP for spinal fusion surgery. METHODS: We conducted this systematic review on topics of spinal fusion surgery with rhBMP application from three database (PubMed, EuropePMC, and Clinicaltrials.gov) with MeSH phrases such as "rh-BMP," "rhBMP," "spine surgery," "spinal arthrodesis," and "spinal fusion" were searched (using the Boolean operators "and" and "or"). Our research includes all articles, as long as published in English language. In the face of disagreement between the two reviewers, we discussed it together until all authors reached a consensus. The primary key outcome of our study is the incidence of cancer following rhBMP implantation. RESULTS: Our study included a total of 8 unique studies (n = 37,682). The mean follow-up varies among all studies, with the longest follow-up is 66 months. Our meta-analysis showed that exposure to rhBMP in spinal surgery did increase the risk of cancers (RR 1.85, 95%CI [1.05, 3.24], p = 0.03). CONCLUSIONS: Our study found that rhBMP was not associated with the increased risk of cancer incidence within the rhBMP cohort. Still, we did face several limitations, in which further studies are needed to confirm the result of our meta-analysis.

Current Trends in Recombinant Human Bone Morphogenetic Protein 2 (rhBMP2) Usage for Spinal Fusion Surgery.

(1) Background: Since first approved by the FDA, on-label and off-label usage of recombinant human bone morphogenetic protein 2 (rhBMP2) for spinal fusion surgeries has become widespread. While many studies have investigated the safety and efficacy of its use, as well as its economic impact, few have looked at the current trends in its on- and off-label use. The goal of this study is to evaluate the current trends of on- and off-label rhBMP2 use for spinal fusion surgery. (2) Methods: A deidentified survey was created and electronically distributed to members of two international spine societies. Surgeons were asked to report their demographic information, surgical experience, and current usage of rhBMP2. They were then presented with five spinal fusion procedures and asked to report if they use rhBMP2 for these indications in their current practice. Responses were stratified between rhBMP2 users vs. non-users and on-label vs. off-label use. Data were analyzed using chi-square with Fisher's exact test for categorical data. (3) Results: A total of 146 respondents completed the survey with a response rate of 20.5%. There was no difference in overall rhBMP2 usage based on specialty, experience, or number of cases per year. Fellowship-trained surgeons and those who practice in the United States were more likely to use rhBMP2. Surgeons who were trained in the Southeast and Midwest regions reported the highest usage rates. rhBMP2 use was more common among fellowship-trained and US surgeons for ALIFs; non-US surgeons for multilevel anterior cervical discectomy and fusions; and fellowship-trained and orthopedic spine surgeons for lateral lumbar interbody fusions. Non-US surgeons were more likely to use rhBMP2 for off-label indications compared to surgeons from the US. (4) Conclusions: While various demographics of surgeons report different rates of rhBMP2 use, off-label use remains relatively commonplace amongst practicing spine surgeons.

Can a low dosage of recombinant human bone morphogenetic protein-2 loaded on collagen sponge induce ectopic bone?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is one of the growth factors that may induce the formation of new bone. The aim was to determine the efficacy of low doses of rhBMP-2 for bone regeneration using a collagen sponge as a carrier. Three doses of rhBMP-2 (1.167, 0.117, and 0.039 mg/mL) were combined with an absorbable collagen sponge (ACS) as a delivery vehicle. The rhBMP-2/ACS implants were placed in the subcutaneous tissues of rat backs. X-ray microcomputed tomography (micro-CT) and histological analysis were used to evaluate bone formation. The samples treated with 1.167 mg/mL of rhBMP-2 showed greater bone formation than the samples treated with 0.117 mg/mL of rhBMP-2 four weeks after surgery. However, there was no evidence of bone formation in the samples that were treated with 0.039 mg/mL of rhBMP-2. It was found that rhBMP-2 was osteogenic even at one-tenth of its manufacturer's recommended concentration (1.167 mg/mL), indicating its potential for clinical use at lower concentrations.

Effect of Bone Morphogenetic Protein-2 Combined With Microfracture for Osteochondral Defect of the Talus in a Rabbit Model.

BACKGROUND: Osteochondral defects of the talus can be effectively treated using microfracture, which is technically safe, accessible, and affordable. However, fibrous tissue and fibrocartilage comprise the majority of tissue repairs resulting from these procedures. These tissue types lack the mechanical characteristics of native hyaline cartilage and might significantly contribute to the decline in long-term outcomes. Recombinant human-bone morphogenetic protein-2 (rhBMP-2) has been shown to promote matrix synthesis and increase cartilage formation, thus enhancing chondrogenesis in vitro. PURPOSE: This study aimed to evaluate the treatment ability of combining rhBMP-2 with microfracture in rabbit talus osteochondral defect. STUDY DESIGN: Controlled laboratory study. METHODS: A full-thickness chondral defect (3 × 3 × 2 mm) was constructed in the center talar dome of 24 New Zealand White male rabbits, which were then divided into 4 groups of 6. Each group received the appropriate treatment: group 1 (control; no treatment of defect), group 2 (microfracture treatment), group 3 (rhBMP-2/hydroxyapatite treatment), and group 4 (microfracture combined with rhBMP-2/hydroxyapatite treatment). Animals were sacrificed at 2, 4, and 6 weeks postoperatively. The International Cartilage Regeneration & Joint Preservation Society macroscopic score, which considers the degree of defect repair, the integration to the border zone, and the macroscopic appearance, was used to assess the repaired tissue's macroscopic appearance. Subchondral bone regeneration in defects was analyzed using micro-computed tomography, and the histological findings were graded using a modified version of the Wakitani scoring system for osteochondral repair. RESULTS: At 2, 4, and 6 weeks, micro-computed tomography analysis revealed that groups 3 and 4 exhibited subchondral bone healing that was more significantly improved compared with groups 1. No sample showed excessive bone growth from the subchondral bone area. According to macroscopic and histological results, group 4 showed higher-quality cartilage and more accelerated cartilage regeneration than the other groups over time. CONCLUSION: These findings show that osteochondral defect repair in a rabbit talus model could be effectively accelerated and improved by combining rhBMP-2 with microfracture. CLINICAL RELEVANCE: Using rhBMP-2 in combination with microfracture may enhance the repair of talar osteochondral lesions.

Creation and preclinical evaluation of a novel mussel-inspired, biomimetic, bioactive bone graft scaffold: direct comparison with Infuse bone graft using a rat model of spinal fusion.

OBJECTIVE: Infuse bone graft is a widely used osteoinductive adjuvant; however, the simple collagen sponge scaffold used in the implant has minimal inherent osteoinductive properties and poorly controls the delivery of the adsorbed recombinant human bone morphogenetic protein-2 (rhBMP-2). In this study, the authors sought to create a novel bone graft substitute material that overcomes the limitations of Infuse and compare the ability of this material with that of Infuse to facilitate union following spine surgery in a clinically translatable rat model of spinal fusion. METHODS: The authors created a polydopamine (PDA)-infused, porous, homogeneously dispersed solid mixture of extracellular matrix and calcium phosphates (BioMim-PDA) and then compared the efficacy of this material directly with Infuse in the setting of different concentrations of rhBMP-2 using a rat model of spinal fusion. Sixty male Sprague Dawley rats were randomly assigned to each of six equal groups: 1) collagen + 0.2 µg rhBMP-2/side, 2) BioMim-PDA + 0.2 µg rhBMP-2/side, 3) collagen + 2.0 µg rhBMP-2/side, 4) BioMim-PDA + 2.0 µg rhBMP-2/side, 5) collagen + 20 µg rhBMP-2/side, and 6) BioMim-PDA + 20 µg rhBMP-2/side. All animals underwent posterolateral intertransverse process fusion at L4-5 using the assigned bone graft. Animals were euthanized 8 weeks postoperatively, and their lumbar spines were analyzed via microcomputed tomography (µCT) and histology. Spinal fusion was defined as continuous bridging bone bilaterally across the fusion site evaluated via µCT. RESULTS: The fusion rate was 100% in all groups except group 1 (70%) and group 4 (90%). Use of BioMim-PDA with 0.2 µg rhBMP-2 led to significantly greater results for bone volume (BV), percentage BV, and trabecular number, as well as significantly smaller trabecular separation, compared with the use of the collagen sponge with 2.0 µg rhBMP-2. The same results were observed when the use of BioMim-PDA with 2.0 µg rhBMP-2 was compared with the use of the collagen sponge with 20 µg rhBMP-2. CONCLUSIONS: Implantation of rhBMP-2-adsorbed BioMim-PDA scaffolds resulted in BV and bone quality superior to that afforded by treatment with rhBMP-2 concentrations 10-fold higher implanted on a conventional collagen sponge. Using BioMim-PDA (vs a collagen sponge) for rhBMP-2 delivery could significantly lower the amount of rhBMP-2 required for successful bone grafting clinically, improving device safety and decreasing costs.

Assessment of Escherichia coli-derived Recombinant Human Bone Morphogenic Protein-2 on Fertilization and Early Embryonic Development in Rats.

OBJECTIVE: Bone morphogenetic protein-2 (BMP-2) impacts fertility in women by affecting the menstrual cycle and embryonic development. We aimed to determine the reproductive toxicity of Escherichia coli (E. coli)-derived recombinant human BMP-2 (rhBMP-2) by measuring changes in the reproductive performance and organs in rhBMP-2-treated rats. METHODS: Overall, 88 male and female rats each were categorized into one control and three experimental groups. rhBMP-2 was intravenously administered to the experimental groups at 0.05, 0.15, and 0.50 mg/kg/day, respectively. The male rats were administered rhBMP-2 daily, starting from 28 days before mating until the day of necropsy (48 days), after which they were euthanized and necropsied. The female rats were administered rhBMP-2 daily, starting from 14 days before mating until 7 days after fertilization (22-36 days), after which they were necropsied 13 days after fertilization. RESULTS: No rhBMP-2-related death occurred throughout the study period. All rhBMP-2-treated groups showed swelling in the tail at the site of rhBMP-2 administration. In the high-dose rhBMP-2 group, the male rats showed a slight reduction in body weight and food consumption, whereas the female rats showed a reduction in the weights of the ovary and oviduct. Examining the fertilization status and necropsy showed no effect of rhBMP-2 on fertility and early embryonic development. The no-observed-adverse-effect level of rhBMP-2 was 0.50 mg/kg/day in all rats. CONCLUSION: rhBMP-2 had no reproductive toxicity on the reproductive performance and organs in female and male rats. Therefore, these results provide new toxicology information on E. coli-derived rhBMP-2 as a therapeutic protein.

Improving Bone Formation by Guided Bone Regeneration Using a Collagen Membrane with rhBMP-2: A Novel Concept.

We examined whether recombinant human bone morphogenetic protein-2 (rhBMP-2) when applied to collagen membranes, would reinforce them during guided bone regeneration. Four critical cranial bone defects were created and treated in 30 New Zealand white rabbits, including a control group, critical defect only; group 1, collagen membrane only; group 2, biphasic calcium phosphate (BCP) only; group 3, collagen membrane + BCP; group 4, collagen membrane with rhBMP-2 (1.0 mg/mL); group 5, collagen membrane with rhBMP-2 (0.5 mg/mL); group 6, collagen membrane with rhBMP-2 (1.0 mg/mL) + BCP; and group 7, collagen membrane with rhBMP-2 (0.5 mg/mL) + BCP. After a 2-, 4-, or 8-week healing period, the animals were sacrificed. The combination of collagen membranes with rhBMP-2 and BCP yielded significantly higher bone formation rates compared to the other groups (control group and groups 1-5 < groups 6 and 7; p < 0.05). A 2-week healing period yielded significantly lower bone formation than that at 4 and 8 weeks (2 < 4 = 8 weeks; p < 0.05). This study proposes a novel GBR concept in which rhBMP-2 is applied to collagen membranes outside instead of inside the grafted area, thereby inducing quantitatively and qualitatively enhanced bone regeneration in critical bone defects.

Experience With Recombinant Human Bone Morphogenetic Protein-2 in Posterior Lumbar Interbody Fusion: A Retrospective Review of 1019 Procedures.

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with an activated collagen scaffold (Infuse; Medtronic, MN) has been used to facilitate lumbar intervertebral fusion; however, data regarding its efficacy are inconsistent. We aimed to assess the efficacy of rhBMP-2 when used in posterior lumbar interbody fusion (PLIF) by analyzing the rate of reoperation for nonunion and patient-reported outcome measures in a large retrospective case series. We also aimed to assess the impact of patient and surgical factors on rates of reoperation and determine frequency of complications. METHODS: Prospectively collected data from a single-surgeon database of consecutive PLIFs (minimum 18-month follow-up) were retrospectively analyzed. PLIF was performed with pedicle screw instrumentation, intervertebral spacers, and locally harvested bone graft to which rhBMP-2 and bone marrow aspirate (BMA) were added. Multivariate logistic regression was used to determine the influence of patient and surgical factors on the primary outcome: reoperation for confirmed nonunion. RESULTS: A total of 1019 operations at 1485 levels across 908 patients were analyzed. Mean duration of follow-up was 51.7 ± 30.0 months (range 18-172). Twelve patients required reoperation for nonunion (1.2%). Increasing body mass index was found to be significant in predicting reoperation (OR 1.114, P = 0.046). Postoperative radiculitis was common (42%) but transient in most cases. There were significant and sustained improvements in patient-reported outcome measures postoperatively. Four cases of osteolysis and 5 of epidural cyst were recorded, and a reduction of rhBMP-2 dose seemed to ameliorate these sequelae. CONCLUSION: In this large retrospective observational study, PLIF performed with rhBMP-2 and BMA resulted in a low rate of clinically significant nonunion and significant improvement in patient-reported outcomes. Transient radiculitis was common. Osteolysis and epidural cyst formation were rare and possibly related to dosage. CLINICAL RELEVANCE: rhBMP-2 is effective when used in PLIF, resulting in a high rate of fusion and improved patient outcomes, and it has an acceptable safety profile.

Chaperone-mediated production of active homodimer human bone morphogenetic protein - 2 in E. coli.

Human bone morphogenetic protein 2 (hBMP-2) plays a leading role in the process of osteogenesis and is one of the key components of osteoplastic materials, ensuring their high osteoinduction. In order to obtain a homodimeric form hBMP-2 using the E. coli expression system, a number of problems associated with refolding in vitro and purification from monomer and oligomeric forms must be solved. The developed method for co-expression of the target protein with chaperone proteins makes it possible to obtain the biologically active homodimeric form of hBMP-2 in vivo. Purification with simple ion-exchange sorbents without the use of denaturing reagents affecting the structure of the protein molecule provides a chromatographic purity of the product of at least 97%. The expressed hBMP-2 was identified by Western blotting and the LC-ESI-TOF mass spectrometry confirmed its molecular weight of 26052.72 Da. Circular dichroism spectroscopy showed that recombinant hBMP-2 has a native secondary structure.

Long-Term Changes in Adipose Tissue in the Newly Formed Bone Induced by Recombinant Human BMP-2 In Vivo.

Recombinant human bone morphogenetic protein-2 (rhBMP-2) induces osteogenesis and adipogenesis in bone scaffolds. We evaluated rhBMP-2-induced long-term changes in adipose tissue in the newly formed bone in different scaffolds forms. Bovine bone particles and blocks were grafted along with rhBMP-2 in the subperiosteal space of a rat calvarial bone, and the formation of new bone and adipose tissue were evaluated at 6 and 16 weeks after the surgery. The bone mineral density (BMD) and trabecular thickness (TbTh) of the 16w particle group were significantly higher than those of the 6w particle group (p = 0.018 and 0.012, respectively). The BMD and TbTh gradually increased in the particle group from weeks 6 to 16. The average adipose tissue volume (ATV) of the 6w particle group was higher than that of the 16w particle group, although the difference was not significant (p > 0.05), and it decreased gradually. There were no significant changes in the bone volume (BV) and BMD between the 6w and 16w block groups. Histological analysis revealed favorable new bone regeneration in all groups. Adipose tissue was formed between the bone particles and at the center in the particle and block groups, respectively. The adipose tissue space decreased, and the proportion of new bone increased in the 16w particle group compared to that in the 6w group. To summarize, in the particle group, the adipose tissue decreased in a time-dependent manner, BMD and TbTh increased, and new bone formation increased from 6 to 16 weeks. These results suggest that rhBMP-2 effectively induces new bone formation in the long term in particle bone scaffolds.

Bone Substitute Options for Spine Fusion in Patients With Spine Trauma-Part I: Fusion Biology, Autografts, Allografts, Demineralized Bone Matrix, and Ceramics.

Spinal trauma accounts for a large portion of injuries to the spine area, particularly as societies are entering an era of aging populations. Consequently, spine fractures accompanied by osteoporosis are becoming more prevalent. Achieving successful fusion surgery in patients with spine fractures associated with osteoporosis is even more challenging. Pseudarthrosis in the spine does not yield clinically favorable results; however, considerable effort has been made to achieve successful fusion, and the advancement of bone graft substitutes has been particularly crucial in this regard. Autograft bone is considered the best fusion material but is limited in use due to the quantity that can be harvested during surgery and associated complications. Accordingly, various bone graft substitutes are currently being used, although no specific guidelines are available and this mainly depends on the surgeon's choice. Therefore, the purpose of this review, across part I/II, is to summarize bone graft substitutes commonly used in spine surgery for spine fusion in patients with spine trauma and to update the latest knowledge on the role of recombinant human bone morphogenetic protein-2.

Histological and Immunohistochemical Analysis of the Effects of Topical Melatonin Treatment Associated with Collagen Sponge and rhBMP-2 Protein on Bone Remodeling.

Extensive bone defect healing is an important health issue not yet completely resolved. Different alternative treatments have been proposed but, in face of a critical bone defect, it is still very difficult to reach a complete regeneration, with the new-formed bone presenting all morphological and physiological characteristics of a normal, preinjury bone. Topical melatonin use has shown as a promising adjuvant for bone regeneration due to its positive effects on bone metabolism. Thus, to search for new, safe, biological techniques that promote bone repair and favor defect healing, we hypothesized that there is a synergistic effect of melatonin treatment associated with rhBMP-2 to guide bone regeneration. This study aimed to investigate bone repair effects of topical melatonin administration in different concentrations (1, 10, and 100 µg), associated or not with rhBMP-2. Surgical-induced bone defect healing was qualitatively evaluated through histopathological analysis by light microscopy. Additionally, quantitative stereology was performed in immunohistochemistry-prepared tissue to identify angiogenic, osteogenic, and osteoclastogenic factors. Quantification data were compared between groups by the ANOVA/Tukey test and differences were considered significant when p < 0.05. Our results showed that the presence of the scaffold in the bone defect hindered the process of bone repair because in the group treated with "blood clot + scaffold" the results of bone formation and immunolabeling were reduced in comparison with all other groups (treated with melatonin alone or in association with rhBMP-2). Statistical analysis revealed a significant difference between the control group (bone defect + blood clot), and groups treated with different concentrations of melatonin in association with rhBMP-2, indicating a positive effect of the association for bone repair. This treatment is promising once it becomes a new safe alternative technique for the clinical treatment of fractures, bone defects, and bone grafts. Our results support the hypothesis of the safe use of the association of melatonin and rhBMP-2 and have established a safe and effective dose for this experimental treatment.

The osteogenesis effect of rhBMP2-loaded calcium phosphate cements in repairing dental extraction sockets.

PURPOSE: After extracting impacted mandibular third molars (IMM3), the resulting bone loss at the distal surface of the distal root of mandibular second molars (MM2) is responsible for the poor stability of MM2. This study aimed to identify the clinical osteogenesis effect of recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded calcium phosphate cements (CPCs) and rhBMP-2 delivery systems (rhBMP-2/CPCs, named CPCII) on bone loss repair at the distal surface of the MM2 distal root after IMM3 extraction. METHODS: Written informed consent was obtained from every participant whose IMM3 needed extraction. The impact of IMM3 on both sides was basically identical. From April 2014 to March 2016, extraction of IMM3 was performed in 9 patients (5 males/4 females, 26-42 years old). One side was randomly selected as the experimental group, and CPCII systems were implanted into the distal surface of the distal root in dental extraction sockets. The wounds on the other side were sutured and allowed to heal naturally (be treated as the control group). New bone formation in the alveolar fossa was detected 3 and 12 months after the operation by cone-beam computed tomography (CBCT) to measure the distance from the cementoenamel junction (CEJ) to the crest of the alveolar ridge (CAR). RESULTS: The CAR-CEJ distance on the test side was less than that on the control side (P<0.5). CONCLUSION: The quantity of new bone formation in the experimental group was greater than that in the control group. CPCII systems have osteogenic potential in the healing process of tooth extraction sockets.