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Bone morphogenetic proteins are a group of structurally related proteins within the TGF-β superfamily of proteins with a diverse repertoire of functions in embryonic and adult organisms. As is apparent from the name, the members first characterized participate in bone growth, development, and remodeling. The "morphogenic" activity per se is defined as the induction of a recapitulation of endochondral bone formation by appropriate stem cells. The regenerative capacity of bone has been recognized since ancient times. The mechanism, applications, and conceptual basis of bone transplantation, bone implantation, ectopic bone formation, and exogenously induced bone formation have been studied by many investigators for more than a century. This review examines the efforts to characterize this activity in the European and American literature over approximately the last century. Because of the inherently complex nature of the process induced by these molecules (inflammation, stem cell proliferation, cartilage differentiation, replacement of cartilage with bone) it is important to evaluate previous investigations through a histological perspective. The cellular basis of the contemporary bioassay for BMP activity is illustrated and discussed from the histological point of view.

Purpose: A retrospective database review was carried out to evaluate the trends and demographics of rhBMP utilization in single-level posterior lumbar fusion (PLF) in the United States., Methods: Patients who underwent single-level PLF from 2005 to 2011 were identified by searching ICD-9 diagnosis and procedure codes in the PearlDiver Patient Records Database (PearlDiver Technologies, Fort Wayne, IN, USA), a national database of orthopaedic insurance records. The year of procedure, age, gender, and region of the United States were recorded for each patient. Results were reported for each variable as the incidence of procedures identified per 100,000 patients searched in the database., Results: Totally 5158 patients had single-level PLF in this study. The average rate of single-level PLF with rhBMP utilization maintained at a relatively stable level (19.1-23.5%) from 2005 to 2009, but sharply decreased to 6.8% in 2010 and 6.9% in 2011. The overall incidence of single-level PLF without rhBMP (1.37 cases per 100,000 patients) was more than five times of the incidence of single-level PLF with rhBMP (0.27 cases per 100,000 patients) (P < 0.01). The average rate of single-level PLF with rhBMP utilization is highest in Midwest (18.7%), followed by West (18.4%), South (16.4%) and Northeast (11.5%). The highest incidence of single-level PLF with rhBMP was observed in the group aged 70-74 years with an incidence of 0.33 per 100,000 patients., Conclusions: The incidence of rhBMP utilization in single-level PLF increased from 2006 to 2009, but dropped to a low level in 2010 and 2011. The Northeast region had the lowest incidence of rhBMP utilization. The group aged 70-74 years trended to have the higher incidence of single-level PLF with rhBMP utilization.

In an attempt to enhance the potential to achieve a solid arthrodesis and avoid the morbidity of harvesting autologous iliac crest bone (AICB) for a lumbar fusion, numerous alternatives have been investigated. The use of these fusion adjuncts has become routine despite a lack of convincing evidence demonstrating a benefit to justify added costs or potential harm. Potential alternatives to AICB include locally harvested autograft, calcium-phosphate salts, demineralized bone matrix (DBM), and the family of bone morphogenetic proteins (BMPs). In particular, no option has created greater controversy than the BMPs. A significant increase in the number of publications, particularly with respect to the BMPs, has taken place since the release of the original guidelines. Both DBM and the calciumphosphate salts have demonstrated efficacy as a graft extender or as a substitute for AICB when combined with local autograft. The use of recombinant human BMP-2 (rhBMP-2) as a substitute for AICB, when performing an interbody lumbar fusion, is considered an option since similar outcomes have been observed; however, the potential for heterotopic bone formation is a concern. The use of rhBMP-2, when combined with calcium phosphates, as a substitute for AICB, or as an extender, when used with local autograft or AICB, is also considered an option as similar fusion rates and clinical outcomes have been observed. Surgeons electing to use BMPs should be aware of a growing body of literature demonstrating unique complications associated with the use of BMPs.

Study Design: The role of bone morphogenetic protein binding peptide (BBP) in bone formation is reviewed from basic science studies and potential clinical application., Objective: We review the discovery and early scientific studies of BBP with emphasis on potential future clinical applications., Summary of Background Data: Biologics delivered locally to enhance bone formation are of increasing importance, particularly in spinal fusion. The most useful agents currently available are bone morphogenetic proteins (BMPs). The indications for recombinant human BMP are expanding; however, certain disadvantages including high costs, unwanted ectopic bone formation, and local inflammatory reaction are becoming more prevalent. As a result, alternate strategies are being developed to provide safer, less expensive, and more efficacious adjuvant agents., Methods: This study reviews the existing published data and early experimental results, and explores potential clinical applications of BBP., Results: BBP is a specific binding protein for BMP with an intermediate affinity, which makes it an ideal "slow release" agent., Conclusion: BBP may reduce the time to fusion and more thoroughly control the distribution of bone healing in spinal fusion. Further study is ongoing to explore clinical applications.

Study Design: Systematic review., Objective: The objectives of this systematic review were to identify the character and rates of complications in patients after the use of BMP in spine fusion surgery and to determine whether there is a dose-response relationship of BMP with complications., Summary of Background Data: BMP is used on-label for ALIF with LT-CAGE and off-label for various spine fusion applications in the cervical, thoracic, and lumbar spines because of its effectiveness in promoting arthrodesis. Multiple studies published over the past several years have highlighted complications associated with BMP in a variety of clinical fusion scenarios. There are no systematic reviews on this topic, and thus, the complication profile of off-label use or physician directed use of BMP in spinal fusion surgery is not well characterized. Some of the reported complications are unique to BMP, which underscores the need for this thorough literature review., Methods: A systematic review of the English language literature was performed for articles published between 1990 and June 2009. Electronic databases and reference lists of key articles were searched to identify articles examining the use of BMP in spine surgery. Two independent reviewers assessed the level of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria and disagreements were resolved by consensus., Results: Two hundred forty-' articles that assessed outcomes after BMP use in spinal surgery were identified from the literature; of these, 31 articles were selected for inclusion. We determined that multiple complications are associated after the use of rhBMP-2 in both cervical and lumbar spine fusion surgery. There is a mean incidence of 44%, 25%, and 27% of resorption, subsidence, and interbody cage migration reported for lumbar spine interbody fusion surgery although reoperation or long-term detrimental effect was rare. Cervical studies report a mean 5.8% of postoperative soft tissue problems, including dysphagia, when rhBMP-2 is used for ventral cervical fusion. It was determined that the strength of evidence of the peer-reviewed literature that report on types of complications is high for the lumbar and low for the cervical spine, respectively, and that the current strength of evidence on rates of complications with BMP is moderate and low, respectively., Conclusion: The complication profile of BMP-2 for ALIF with LT-CAGE is well characterized. Because of the lack of substantive data, the same is not true for other types of lumbar fusions, or for cervical or thoracic fusion applications. BMP has been associated with a variety of unique complications in the ventral cervical and lumbar spines. The published data on BMP fail to precisely profile this product's use in fusion surgery; hence, it should be used only after a careful consideration of the relevant data. Well-designed and executed studies are necessary to completely define the incidence of various complications relative to type of BMP, type and region of fusion, surgical technique, dose, and carrier, and importantly, to define the natural history and management of associated complications.

BMP-binding peptide (BBP) enhances the osteogenic activity of recombinant human bone morphogenetic protein-2 (rhBMP-2), but the mechanism underlying the enhancement remains unclear. We aimed to elucidate the potential enhanced efficacy of BBP using critical-sized segmental femoral bone defects in rats. Seventy defects in seven groups of rats were filled with various amounts (0, 2, 5, and 10 microg) of rhBMP-2 with or without 1000 microg BBP. Radiographs were obtained after 4 and 8 weeks. The animals were euthanized at 8 weeks, and femoral specimens were assessed manually, evaluated for bone volume using microcomputed tomography, and subjected to histological or biomechanical analysis. Although 10 microg rhBMP-2 yielded consistent results in terms of bone healing and quality of bone repair across the segmental defect, lower doses of rhBMP-2 failed to induce satisfactory bone healing. However, the combined administration of lower doses of rhBMP-2 and BBP induced the formation of significantly large amounts of bone. Our results suggest that the combined administration of rhBMP-2 and BBP facilitates bone healing and has potential clinical applications., ((c) 2009 Orthopaedic Research Society.)

Background: Demineralized bone matrix is an osteoinductive allograft derived from processed bone that is commonly mixed with autogenous bone in fusion procedures to treat diseases of the spine. An increasing number of demineralized bone matrix-based products are commercially available for spinal fusion procedures, but osteoinductive variability has been found not only across different products but also among production lots from the same demineralized bone matrix formulation. The purpose of this study was to assess the lot-to-lot variability across a single demineralized bone matrix-based product in terms of both extracted bone morphogenetic protein (BMP) concentrations (in vitro) and fusion performance in rats (in vivo). The goal was also to determine whether the in vitro measures could sufficiently and accurately predict the in vivo fusion performance of different demineralized bone matrix-based product lots., Methods: BMP-2 and BMP-7 were extracted from ten production lots of InterGro DBM Putty and quantified with use of ELISA (enzyme-linked immunosorbent assay). A posterolateral lumbar spinal fusion was performed on forty athymic rats with implantation of a demineralized bone matrix-based product. Fusion success was determined at eight weeks with use of radiographs and manual palpation of the segments. Logistic regression was used to determine the predictive abilities of BMPs., Results: Significant lot-to-lot variability was found in terms of both BMP concentrations (22 to 110 pg of BMP-2 per milligram of product and 44 to 125 pg of BMP-7 per milligram of product) and in vivo rates of fusion (0% to 75%; p < 0.04 for all). BMP-2 and BMP-7 concentrations correlated positively with each other across lots (r = 0.77, p < 0.0001). Most notably, extracted amounts of BMP-2 and BMP-7 each predicted in a dose-dependent manner the in vivo fusion performance in rats (R(2) = 0.32, p < 0.01 for BMP-2, and R(2) = 0.22, p < 0.009 for BMP-7)., Conclusions: Assays for demineralized bone matrix-extracted BMP-2 and BMP-7 levels may be feasible and sufficient for predicting spinal fusion performance of individual production lots from the same demineralized bone matrix-based product.

Background Context: Recombinant bone morphogenetic proteins (rhBMPs) have been used successfully in clinical trials. However, large doses of rhBMPs were required to induce adequate bone repair. Collagen sponges (CSs) have failed to allow a more sustained release of rhBMPs. Ongoing research aims to design carriers that allow a more controlled and sustained release of the protein. E-Matrix is a injectable scaffold matrix that may enhance rhBMP activity and stimulate bone regeneration., Purpose: The purpose of this study was to test E-Matrix as a carrier for rhBMPs in a CS and examine its feasibility in clinical applications by using a rat spinal fusion model., Patient Sample: A total of 80 Lewis rats aged 8-16 weeks were divided into nine groups., Study Design/setting: Rat spinal fusion model., Outcome Measures: Radiographs were obtained at 4, 6, and 8 weeks. The rats were sacrificed and their spines were explanted and assessed by manual palpation, high-resolution microcomputed tomography (micro-CT), and histologic analysis., Methods: Group I animals were implanted with CS alone (negative control); Group II animals with CS containing 10microg rhBMP-2 (positive control); Group III animals with CS containing 3microg rhBMP-2; Group IV animals with CS containing 3microg rhBMP-2 and E-Matrix; Group V animals with CS containing 1microg rhBMP-2; Group VI animals with CS containing 1microg rhBMP-2 and E-Matrix; Group VII animals with CS containing 0.5microg rhBMP-2; Group VIII animals with CS containing 0.5microg rhBMP-2 and E-Matrix; and Group IX animals with CS and E-Matrix without rhBMP-2., Results: Radiographic evaluation, micro-CT, and manual palpation revealed spinal fusion in all rats in the BMP-2 and E-Matrix groups (IV, VI, and VIII) and high-dose BMP-2 groups (II and III). Four spines in the 3microg rhBMP-2 group (V) fused, and one spine in the 0.5microg rhBMP-2 group (VII) exhibited fusion. No spines were fused in Groups I (CS alone) and IX (E-Matrix alone). The volume of new bone in the area between the tip of the L4 transverse process and the base of the L5 transverse process in Group IV was equivalent to the volumes observed in Group II., Conclusion: E-matrix enhances spinal fusion as a carrier for rhBMP-2 in a rat spinal fusion model. The results of this study suggest that E-Matrix as a growth factor carrier may be applicable to spinal fusion and may improve rhBMP-2's activity at the fusion site.

Study Design: A prospective 8-week interventional trial employing a rat model of spinal fusion to test the effect on bone morphogenetic protein binding peptide (BBP) on rhBMP-2 induced bone healing., Objectives: To determine if the addition of BBP to the collagen sponges used as a carrier for rhBMP-2 reduces the amount of rhBMP-2 required to achieve a satisfactory clinical outcome., Summary of Background Data: Bone morphogenetic proteins (BMPs) although effective in promoting osseous growth and spinal fusion have limitations in their extensive use because of higher costs and possible adverse effects including ectopic bone formation and local inflammatory reaction, particularly in the cervical spine., Methods: Posterolateral intertransverse process spinal fusion at L4-L5 was performed in Lewis rats. Two doses of BBP (500 microg, and 1000 microg) were tested with or without "low dose" (1 microg) rhBMP-2 and the results were compared with the low dose (1 microg) rhBMP-2. Fusion was evaluated by radiology, histology, and manual palpation tests., Results: Radiology revealed significant earlier fusion with 1000 microg BBP + 1 microg BMP-2 combination when compared with low dose BMP-2 (1 microg) only (P < 0.05). Manual palpation and histology at eighth week revealed higher rate of fusion with the same combination with a nearly significant difference (P = 0.057)., Conclusion: Specific growth factor binding agents, such as BBP, can be compounded into carriers used in fusion procedures to decrease the dosage of BMP and possibly decrease the side effects which are most likely dose-related. This may also decrease costs and improve clinical outcomes.

Study Design: Rat spinal fusion model., Objective: This study aimed to assess the ability of rat bone marrow cells (RBMCs) transfected with bone morphogenetic protein (BMP)-2-containing lentivirus to induce a posterolateral spinal fusion in a rat model., Summary of Background Data: Spinal arthrodesis is a commonly performed spinal procedure and autograft remains the standard for achieving spinal fusion. However, its procurement is associated with significant morbidity, and the rate of pseudoarthrosis has been reported to be 5% to 43%. Nonunion frequently leads to an unsatisfactory resolution of clinical symptoms and usually results in high medical costs and morbidity as well as the need for additional surgeries. These problems have led surgeons to search for alternative solutions to stimulate bone formation. Recombinant BMPs have also been used successfully in clinical trials. However, large doses of BMPs were required to induce adequate bone repair. The development of a regional gene therapy may be a more efficient method to deliver proteins to a specific anatomic site. Furthermore, adeno-BMP-2-producing rat bone marrow-derived cells have been used successfully to induce posterior spinal fusion. Recently, lentiviral vectors on the basis of human immunodeficiency virus have been developed for gene therapy. Lentiviruses are capable of insertion into the host genome, ensuring a prolonged gene expression. However, safety issues are a major concern when adopting these vectors for clinical use., Methods: In vitro study, we used RBMCs transfected with lentivirus vectors encoding BMP-2 (Lenti-BMP-2), RBMCs transfected with lentivirus vectors encoding the green fluorescent protein (GFP) (Lenti-GFP), and untransfected RBMCs; the latter 2 were used as controls. Alkaline phosphatase (ALP) staining and ALP activity were compared between the groups to assess the ability of the Lenti-BMP-2-transfected RBMCs to stimulate osteoblastic differentiation. In the rat posterolateral spine fusion model, the experimental study comprised 4 groups. Group 1 comprised 6 animals that were implanted with a collagen sponge containing 5 million RBMCs transfected with Lenti-BMP-2. Group 2 comprised 3 animals that were implanted with a collagen sponge containing 5 million RBMCs transfected with Lenti-GFP. Group 3 comprised 6 animals that were implanted with a collagen sponge containing 5 million untransfected RBMCs. Group 4 comprised 3 animals that were implanted with a collagen sponge alone. The rats were assessed by radiographs obtained at 4, 6, and 8 weeks. After death, their spines were explanted and assessed by manual palpation, high-resolution microcomputerized tomography, and histologic analysis., Results: The ALP staining was significantly greater in the Lenti-BMP-2-transfected RBMCs than in the untransfected RBMCs and the Lenti-GFP-transfected RBMCs. The ALP activity was 3-fold greater in the Lenti-BMP-2-transfected RBMCs than in the untransfected RBMCs and the Lenti-GFP-transfected RBMCs. In the rat spine fusion model, radiographic evaluation, high-resolution microcomputerized tomography, and manual palpation revealed spinal fusion in all the rats in Group 1 at 8 weeks. Groups 2, 3, and 4 comprised the control group. None of the rats in the control group (0 of 12) developed fusion at L4-L5., Conclusions: The present study demonstrated that BMP-2-producing RBMCs, created through lentiviral gene transfer, induced sufficient spinal fusion. The use of lentiviral vectors that contain the cDNA for BMP-2 will be a novel and promising approach for a spinal fusion strategy.

Study Design: Rat spinal fusion model., Objective: This study aimed to compare the efficacy of lentiviral gene therapy, and adenoviral gene therapy in inducing spinal fusion in an immune competent rat spinal fusion model., Summary of Background Data: Recombinant bone morphogenetic proteins (BMPs) have also been used for spinal fusion successfully in clinical trials. However, large doses of BMPs are required to induce adequate bone repair. Hence, regional gene therapy may be a more efficient method to deliver proteins to a specific anatomic site. Recently, lentiviral vectors based on human immunodeficiency virus have been developed for gene therapy. However, lentiviral gene therapy for spinal fusion has not been compared with adenoviral gene therapy., Methods: Lewis rats were divided into 7 groups. group I, II, III, and IV rats were implanted with a collagen sponge containing rat bone marrow cells (RBMCs) transfected with Lenti-BMP-2, Adeno-BMP-2, Lenti-GFP, Adeno-LacZ, respectively. Group V, VI, and VII rats were implanted with a collagen sponge containing recombinant BMP-2, a collagen sponge containing untransfected RBMCs, and a collagen sponge alone, respectively. The rats were assessed at 4, 6, and 8 weeks after implantation. After sacrificing the rats, their spines were explanted and assessed by manual palpation, high-resolution microcomputed tomography, and histologic analysis., Results: Spinal fusion was observed in all animals in group I, II, and V rats at 8 weeks. None of the rats in groups III, IV, VI, and VII showed spinal fusion. The volumes of the new bone in the area between the L4 and L5 transverse processes were greater in group I rats than in group II, and V rats with a significant difference., Conclusion: BMP-2-producing RBMCs developed using lentiviral gene transfer induced more abundant bone within the fusion mass than the RBMCs transduced via adenoviral gene transfer and recombinant protein therapy.

Background: Mesenchymal stem cells derived from human liposuction aspirates, termed processed lipoaspirate cells, have been utilized as cellular delivery vehicles for the induction of bone formation in tissue engineering and gene therapy strategies. In this study, we sought to evaluate the efficacy of bone morphogenetic protein (BMP)-2-producing adipose-derived stem cells in inducing a posterolateral spine fusion in an athymic rat model., Methods: Single-level (L4-L5) intertransverse spinal arthrodesis was attempted with use of a type-I collagen matrix in five groups of athymic rats, with eight animals in each group. Group I was treated with 5 x 10(6) adipose-derived stem cells transduced with an adenoviral vector containing the BMP-2 gene; group II, with 5 x 10(6) adipose-derived stem cells treated with osteogenic media and 1 microg/mL of recombinant BMP-2 (rhBMP-2); group III, with 10 microg of rhBMP-2; group IV, with 1 microg of rhBMP-2; and group V, with 5 x 10(6) adipose-derived stem cells alone. The animals that showed radiographic evidence of healing were killed four weeks after cell implantation and were examined with plain radiographs, manual palpation, microcomputed tomography scanning, and histological analysis., Results: All eight animals in group I demonstrated successful spinal fusion, with a large fusion mass, four weeks postoperatively. Furthermore, group-I specimens consistently revealed spinal fusion at the cephalad level (L3 and L4), where no fusion bed had been prepared surgically. In contrast, despite substantial BMP-2 production measured in vitro, group-II animals demonstrated minimal bone formation even eight weeks after implantation. Of the groups treated with the application of rhBMP-2 alone, the one that received a relatively high dose (group III) had a higher rate of fusion (seen in all eight specimens) than the one that received the low dose (group IV, in which fusion was seen in four of the eight specimens). None of the group-V animals (treated with adipose-derived stem cells alone) demonstrated successful spine fusion eight weeks after the surgery., Conclusions: Adipose-derived stem cells show promise as gene transduction targets for inducing bone formation to enhance spinal fusion in biologically stringent environments.

Background Context: Because pseudarthrosis remains a clinically significant complication after spinal arthrodesis, the role of recombinant bone morphogenetic proteins (BMPs) is continually evaluated in spine surgery., Purpose: This article reviews the important literature in clinical research involving the use of BMPs in the augmentation of spinal fusion., Study Design/setting: Review article., Methods: A literature search was performed via MEDLINE through PubMed with the dates January 1960 to July 2007 using the keywords "bone morphogenetic protein, BMP, spinal arthrodesis, and/or bone healing." Pertinent preclinical and clinical publications were chosen based on relevance and quality for inclusion in this study., Results: Publications focused on the historical context and potential clinical applications using BMP were selected to delineate the risks, benefits, and current indications for the augmentation of spinal arthrodesis., Conclusions: Although multiple commercially available recombinant BMPs have demonstrated clinical success in interbody and posterolateral fusions, the associated costs preclude its routine use in spinal arthrodesis. The spine surgeon must assess each patient individually based on age, bone quality, diagnosis, comorbidities, and risks of nonunion to determine the cost effectiveness of the use of BMP to augment spinal fusion.

Study Design: Rat spinal fusion model., Objective: To compare the efficacy of human adipose tissue-derived mesenchymal stem cells (HATDMSCs) and human bone marrow-derived mesenchymal stem cells (HBMDMSCs) transduced with an adenovirus containing the cDNA for bone morphogenetic proteins (BMP)-2 for inducing spinal fusion in an athymic rat model., Summary of Background Data: Recombinant BMPs have successfully induced spinal fusion in clinical trials. However, large doses are required for adequate bone repair. Regional gene therapy may deliver proteins to specific anatomic sites more efficiently. Gene transfer techniques using HATDMSCs have recently been tested., Methods: Spinal fusion was performed in rats with different treatments: Group I (n = 10) collagen sponge containing HATDMSCs transfected with adeno-BMP-2, Group II (n = 10) collagen sponge containing HBMDMSCs transfected with adeno-BMP-2, Group III (n = 10) collagen sponge containing recombinant BMP-2 (10 mug), Group IV (n = 6) collagen sponge containing HATDMSCs transfected with adeno-LacZ, Group V (n = 6) collagen sponge containing HBMDMSCs transfected with adeno-LacZ, and Group VI (n = 6) collagen sponge alone. Radiographs were obtained at 4, 6, and 8 weeks. After sacrifice, the rat spines were assessed by manual palpation, microcomputed tomography, and histologic analysis., Results: At 8 weeks, spinal fusion was observed in all Groups I, II, and III rats. 75% (15 of 20) of the gene therapy treatment animals (Groups I and II rats) had spontaneous extension of the fusion to a second level. No Groups IV, V, and VI rats developed fusion. New bone volume was significantly greater in Groups I and II than in Group VI., Conclusion: HATDMSCs transfected with adeno-BMP-2 induce abundant bone formation and have a similar posterolateral spinal fusion in rats as similarly genetically modified HBMDMSCs. Both are potential strategies for spinal fusion and may be a more efficient method of obtaining spinal fusion over currently used grafting substances.

Study Design: This experimental study consisted of four groups. In Group I, 8 animals were implanted with a collagen sponge containing 5 million human-derived bone marrow cells (HBMCs) infected with the BMP-2-containing adenovirus. In Group II, 5 animals were implanted with a collagen sponge containing 5 million HBMCs, which had been infected with an adenovirus containing the cDNA for the lacZ gene. In Group III, 5 animals were implanted with a collagen sponge containing 5 million uninfected HBMCs. In Group IV, 5 animals were implanted with a collagen sponge alone. All animals were killed at 12 weeks., Objectives: The purpose of this study was to assess the ability of HBMCs infected with a BMP-2 adenovirus to induce a posterolateral spine in an athymic rat model., Summary of Background Data: High pseudarthrosis rates after attempted spinal arthrodesis as well as the morbidity associated with iliac crest bone graft harvest make alternative bone graft materials desirable. Alternatives include allograft bone, demineralized bone matrices, and more recently, recombinant bone morphogenetic proteins. However, high doses of the recombinant protein are required, and a single dose of recombinant protein may not induce a sufficient osteoinductive response in all patients. An alternative strategy is to genetically manipulate cells to overexpress a bone morphogenetic protein., Methods: HBMCs grown in culture were infected with an adenovirus containing the cDNA for BMP-2 (AdBMP-2) or the gene for beta-galactosidase (AdlacZ). Cells were implanted on the decorticated transverse processes of L4-L5 as previously described. Rats were assessed by radiographs at 4-week intervals and were killed at 12 weeks. After death, spines were explanted and assessed by manual palpation and histologic analysis., Results: Eight of eight rats implanted with AdBMP-2-infected HBMCs (Group I) were fused by radiographic evaluation and manual palpation at 12 weeks. Control groups consisted of: 5 rats implanted with the collagen sponge alone (Group II), 5 rats implanted with a collagen sponge and 5 million uninfected HBMCs (Group III), and 5 rats implanted with HBMCs infected with AdlacZ (Group IV). None of the rats in the control groups (0 of 15) developed a fusion at L4-L5., Conclusion: This study demonstrates that human-derived bone marrow cells can be infected with a BMP-2-containing adenovirus and produce sufficient bone in vivo to fuse the lumbar spine.

An economic model was developed to compare costs of stand-alone anterior lumbar interbody fusion with recombinant human bone morphogenetic protein 2 on an absorbable collagen sponge versus autogenous iliac crest bone graft in a tapered cylindrical cage or a threaded cortical bone dowel. The economic model was developed from clinical trial data, peer-reviewed literature, and clinical expert opinion. The upfront price of bone morphogenetic protein (3380 dollars) is likely to be offset to a significant extent by reductions in the use of other medical resources, particularly if costs incurred during the 2 year period following the index hospitalization are taken into account.

Background: Bone morphogenetic proteins (BMPs) are now being used as bone-graft substitutes to enhance spinal fusion. However, the large doses of BMP required to induce a spinal fusion in humans suggests that the delivery of these proteins should be improved. We used ex vivo adenoviral gene transfer to create BMP-2-producing bone marrow cells, and these autologous cells were found to induce a posterolateral fusion of the spine in syngeneic rats., Methods: Intertransverse spinal arthrodesis (L4 and L5) was attempted in ten groups of Lewis rats with 5 x 10 (6) BMP-2-producing rat bone marrow cells (Ad-BMP-2 cells), created through adenoviral gene transfer with guanidine hydrochloride-extracted demineralized bone matrix as a carrier (Group I); 5 x 10 (6) Ad-BMP-2 cells on a collagen sponge carrier (Group II); 10 micro g of recombinant BMP-2 (rhBMP-2) in a guanidine hydrochloride-extracted demineralized bone matrix carrier (Group III); 10 micro g of rhBMP-2 in a collagen sponge carrier (Group IV); autogenous iliac crest bone-grafting (Group V); 5 x 10 (6) beta-galactosidase-producing rat bone marrow cells, created through adenoviral gene transfer with guanidine hydrochloride-extracted demineralized bone matrix as a carrier (Group VI); decortication of the transverse processes alone (Group VII); 5 x 10 (6) uninfected rat bone marrow cells with a guanidine hydrochloride-extracted demineralized bone matrix carrier (Group VIII); guanidine hydrochloride-extracted demineralized bone matrix only (Group IX); or a collagen sponge alone (Group X). Each specimen underwent plain radiography, manual palpation, and histological analysis., Results: All spines in Groups I and II (BMP-2-producing bone marrow cells) and all spines in Groups III and IV were fused at four weeks postoperatively. In contrast, none of the spines in the other groups had fused at a minimum of eight weeks after implantation. Histological analysis of the specimens revealed that the spines that had received BMP-2-producing bone marrow cells (Groups I and II) were filled with coarse trabecular bone postoperatively, whereas those that had received rhBMP-2 (Groups III and IV) were filled with thin, lace-like trabecular bone. All of the other spines, including those that had been treated with autogenous iliac crest bone-grafting (Group V), produced little or no new bone., Conclusion: BMP-2-producing bone marrow cells, created by adenoviral gene transfer, produce sufficient BMP to induce an intertransverse fusion in the rat spine model.

Background Context: Bone grafting is used to augment bone healing and provide stability after spinal surgery. Autologous bone graft is limited in quantity and unfortunately associated with increased surgical time and donor-site morbidity. Alternatives to bone grafting in spinal surgery include the use of allografts, osteoinductive growth factors such as bone morphogenetic proteins and various synthetic osteoconductive carriers., Purpose: Recent research has provided insight into methods that may modulate the bone healing process at the cellular level in addition to reversing the effects of symptomatic disc degeneration, which is a potentially disabling condition, managed frequently with various fusion procedures. With many adjuncts and alternatives available for use in spinal surgery, a concise review of the current bone grafting alternatives in spinal surgery is necessary., Study Design/setting: A systematic review of the contemporary English literature on bone grafting in spinal surgery, including abstract information presented at national meetings., Methods: Bone grafting alternatives were reviewed as to their efficacy in extending or replacing autologous bone graft sources in spinal applications., Results: Alternatives to autologous bone graft include allograft bone, demineralized bone matrix, recombinant growth factors and synthetic implants. Each of these alternatives could possibly be combined with autologous bone marrow or various growth factors. Although none of the presently available substitutes provides all three of the fundamental properties of autograft bone (osteogenicity, osteoconductivity and osteoinductivity), there are a number of situations in which they have proven clinically useful., Conclusions: Alternatives to autogenous bone grafting find their greatest appeal when autograft bone is limited in supply or when acceptable rates of fusion may be achieved with these substitutes (or extenders) despite the absence of one or more of the properties of autologous bone graft. In these clinical situations, the morbidity of autograft harvest is reasonably avoided. Future research may discover that combinations of materials may cumulatively result in the expression of osteogenesis, osteoinductivity and osteoconductivity found in autogenous sources.

Study design: Systematic review. Objectives: The aim of this study is to analyze the complications related to multilevel anterior cervical discectomy and fusion (ACDF) using osteobiologics other than bone morphogenetic protein (BMP). Methods: A systematic review of the literature was conducted using PubMed, EMBASE, Cochrane Library, and ClinicalTrials.gov databases. The search to identify studies reporting complications in multilevel ACDF surgery using osteobiologics other than bone morphogenetic protein was performed in August 2020. The study was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA). Results: A total of 584 articles were found after searching the databases and removing duplicates. Next, screening was performed in a double reviewer process, and 153 eligible articles—with 4 retrospective studies—in full-text were selected; these met all inclusion criteria. A total of 197 patients received 3-level ACDF, while 72 patients received 4-level ACDF. Osteobiologics were used in all selected articles, allograft was used in 4 studies, autologous bone graft was utilized in 3 articles, and hydroxyapatite was used in 1 article. The main complications reported were dysphagia, adjacent segment disease, and pseudarthrosis. Conclusions: Given the limited evidence, no conclusions on complications in multilevel ACDF using osteobiologics other than BMP could be made. However, descriptively, the most common complications found were dysphagia, adjacent segment disease, and pseudoarthrosis. Further prospective studies separately analyzing complications in multilevel ACDF by osteobiologics and a number of treated levels are needed. [ABSTRACT FROM AUTHOR]

Study Design: Systematic review. Objectives: The study's primary objective was to determine how osteobiologic choice affects fusion rates in patients undergoing anterior cervical discectomy and fusion (ACDF). The study's secondary objectives were to 1) determine the optimal timing of fusion assessment following ACDF and 2) determine if osteobiologic type affects the timing and optimal modality of fusion assessment. Methods: A systematic search of PubMed/MEDLINE was conducted for literature published from 2000 through October 2020 comparing anterior fusion in the cervical spine with various osteobiologics. Both comparative studies and case series of ≥10 patients were included. Results: A total of 74 studies met the inclusion criteria. Seventeen studies evaluated the efficacy of autograft on fusion outcomes, and 23 studies assessed the efficacy of allograft on fusion outcomes. 3 studies evaluated the efficacy of demineralized bone matrix, and seven assessed the efficacy of rhBMP-2 on fusion outcomes. Other limited studies evaluated the efficacy of ceramics and bioactive glasses on fusion outcomes, and 4 assessed the efficacy of stem cell products. Most studies utilized dynamic radiographs for the assessment of fusion. Overall, there was a general lack of supportive data to determine the optimal timing of fusion assessment meaningfully or if osteobiologic type influenced fusion timing. Conclusions: Achieving fusion following ACDF appears to remain an intricate interplay between host biology and various surgical factors, including the selection of osteobiologics. While alternative osteobiologics to autograft exist and may produce acceptable fusion rates, limitations in study methodology prevent any definitive conclusions from existing literature. [ABSTRACT FROM AUTHOR]

Purpose: The aim of our study was to determine the effect of Oxy133 and rhBMP2 on fusion rates and new bone formation in a rat posterolateral fusion (PLF) model. Furthermore, we examined whether Oxy133 could inhibit the adipogenesis that is often present in rhBMP2-induced fusions.Methods: Sixty-four male Lewis rats underwent two levels PLF (L3-L5). All animals were randomly divided into eight groups based on the test compound that they received: control (DMSO), low-dose rhBMP2 (0.5 µg), high-dose rhBMP2 (5 µg), low-dose Oxy133 (5 mg), high-dose Oxy133 (20 mg), low rhBMP2 + high Oxy133, high rhBMP2 + high Oxy133, and low rhBMP2 + low Oxy133. Fusion rates were assessed 8 weeks after surgery with manual palpation and plain radiographs. Bone parameters were measured using microCT. Histology was used to evaluate adipogenesis.Results: No fusion was observed in the control group. Based on the manual palpation, 100% fusion was observed in all other groups except in the low-dose rhBMP2 group (69%). At 8 weeks based on X-rays, 100% fusion was observed in the following groups: high-dose rhBMP2, low-dose Oxy133, and low rhBMP2 + low Oxy133. In the other groups, the fusion rates were between 95 and 97%, except for the low rhBMP2 group (72%). We observed similar values in BV/TV ratio at L3-4 when Oxy133 groups were compared to rhBMP2 groups alone (44.62% in high-dose Oxy133 vs. 41.47% in high-dose rhBMP2 and 47.18% in low-dose Oxy133 vs. 54.98% in low-dose rhBMP2). Trabecular thickness was slightly lower in Oxy133 groups compared to rhBMP2 when comparing low- and high-dose groups from each group (118.44 µm for high-dose Oxy133 vs. 122.39 µm for high-dose rhBMP2 and 123.51 µm for low-dose Oxy133 vs. 135.74 µm for low-dose rhBMP2). At the same time, trabecular separation was lower in Oxy133 groups compared to rhBMP2 groups. Similar trends in bone parameters were observed at the L4-5 levels. Fusion masses with low- and high-dose Oxy133 had significantly less adipocytes than rhBMP2 groups that showed robust adipocyte formation.Conclusion: In our study, both low-dose and high-dose Oxy133 produced solid fusions with bone densities similar or higher than in the BMP2 groups. High-dose Oxy133 group had significantly less adipocytes than high- or low-dose rhBMP2 groups. Furthermore, high-dose Oxy133 was able to significantly inhibit high-dose BMP2-induced adipogenesis when combined together. Consistent with the previous reports, our preliminary findings suggest that Oxy133 has a significant potential as an alternative to rhBMP2 in spine fusion. [ABSTRACT FROM AUTHOR]

Background: Previous studies have suggested that the co-expression of two different bone morphogenetic protein (BMP) genes can result in the production of heterodimeric BMPs that may be more potent than homodimers. In this study, combined BMP-2 and BMP-7 gene transfer was performed ex vivo to compare the resulting new bone formation with that of single-BMP gene transfer in a rat spinal fusion model. Methods: Forty-four athymic rats underwent posterolateral fusion at L4-L5 and were implanted with a collagen sponge containing human adipose-derived stem cells. Group A received untreated cells, and the remaining groups received cells transfected with various genes in a lentivirus vector. The transferred genes were GFP (green fluorescent protein) in Group B, BMP-2 in Group C, BMP-7 in Group' D, and both BMP-2 and BMP-7 in Group E. In vitro production of BMP-2 and BMP-7 was quantified by means of an enzyme-linked immunosorbent assay (ELISA) specific to BMP-2 or BMP-7. Osseous fusion was quantified with use of radiography and microcomputed tomography. Results: ELISA demonstrated that Group E, which was treated with both BMP-2 and BMP-7, produced less than one-fourth as much BMP as the groups treated with a single transfected BMP (Groups C and D). Radiographs showed that all of the spines in Groups C, D, and E appeared to be fused by eight weeks; the spines in Groups A and B showed minimal evidence of new bone formation. Measurements confirmed that the mean bone formation area was significantly greater in Groups C, D, and E compared with Groups A and B (p < 0.001). In addition, the bone formation area was significantly greater in Group E compared with Groups C and D (p < 0.001). Conclusions: Combined BMP-2 and BMP-7 ex vivo gene transfer was found to be significantly more effective for inducing new bone formation compared with ex vivo gene transfer of an individual BMP in a rat spinal fusion model. Clinical Relevance: Combined BMP-2 and BMP-7 therapy may lead to efficient bone regeneration. [ABSTRACT FROM AUTHOR]

Concern has been raised because of reports of inflammatory swelling following the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) and recombinant human bone morphogenetic protein-7 (rhBMP-7). The purpose of this study is to compare the inflammatory action of rhBMP-7 with those of rhBMP-2. ELISA assays (IL-6, TNF-α) were used to measure the cytokine response to different concentrations of rhBMP-7 and -2. Recombinant human BMP-7 was absorbed into absorbable collagen sponges and different amounts were implanted either subcutaneously (SC) or intramuscularly (IM) into the backs of rats. Using MRI and MIPAV software, we measured the degree of soft tissue edema at 3 h and at 2, 4, and 7 days postoperatively. After sacrificing rats on day 7 the inflammatory zone and mass were measured and the tissue examined histologically. Soft tissue edema after rhBMP-7 and rhBMP-2 implantation was dose-dependent and peaked at 3 h for the subcutaneous implants and at 2 days for the intramuscular implants. RhBMP-7 was associated with a significantly smaller soft tissue edema volume than was rhBMP-2 only at the highest dose (20 µg/ml). Both rhBMP-2 and rhBMP-7 triggered dose-dependent inflammatory reactions. Compared to rhBMP-2, rhBMP-7 is associated with somewhat smaller soft tissue edema volumes. Although rhBMP-7 is associated with an inflammatory reaction leading to soft tissue edema, at high doses this response is significantly less than that seen with rhBMP-2. Our animal model can be used to test materials that could ameliorate this reaction. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1985-1994, 2012 [ABSTRACT FROM AUTHOR]

Bone morphogenetic proteins (BMPs) and transforming growth factor-beta (TGF-β) contribute to the growth of some skeletal metastases through autocrine stimulation. Secreted phosphoprotein 24 kDa (spp24) has been shown to bind to both BMP-2 and TGF-β and to markedly inhibit the osteogenic properties of rhBMP-2. We hypothesized that the addition of spp24 would sequester autocrine growth factors (especially BMP-2) and reduce tumor growth in a system (A549 human non-small cell lung cancer cell line) where autocrine stimulation by BMP-2 is known to be important. A549 cells were injected into two sites (subcutaneous and intraosseus) in SCID mice with and without the co-injection of BMP-2 and spp24. Tumor growth after 8 weeks was assessed through gross examination, radiological imaging, and histological analysis. Spp24 attenuated the tumor growth enhancing effects of rhBMP-2 and reduced the tumor growth when added to tumor cells that were not treated with BMP-2. We conclude that spp24 can reduce A549 cell tumor growth in both soft tissue and intraosseus environments. We hypothesize that the mechanism for this inhibition is interruption of autocrine stimulation through the sequestration of BMP-2. Spp24 can be developed into a therapeutic agent that can be employed in clinical situations where the inhibitions of BMPs and related proteins is advantageous. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1712-1718, 2011 [ABSTRACT FROM AUTHOR]

Background: Growth factors like bone morphogenetic protein (BMP) are used as bone-graft substitutes to enhance bone growth in clinical situations. However, adverse reactions have been associated with BMP use. We developed a synthetic adjuvant therapy based on the sequence of a BMP-binding protein, secreted phosphoprotein-24 (spp24), which enhances the effects of BMP5 and ameliorates the adverse reactions. Our hypothesis is that a natural proteolytic fragment of spp24 is identical to an osteogenic protein previously described independently by two investigators. To test this hypothesis, spp24 and a truncated form of spp24 were separately implanted with recombinant human BMP-2 (rhBMP-2) in a rodent model of spine fusion. Methods: Two isoforms of spp24 were constructed with use of DNA recombinant technology. Spp24 with or without rhBMP-2 were added to collagen sponges and implanted bilaterally between L4 and L5 transverse processes Radio- graphs were made biweekly, and spines were explanted after eight weeks. Gross evaluation, microquantitative computed tomography study, and histological analysis were performed to evaluate bone growth. Results: Animals that received full-length spp24 and rhBMP-2 exhibited a complete obliteration of bone growth, while animals with the truncated form in combination with rhBMP-2 exhibited a mild inhibition to bone growth, with bone area measured from radiographs. Manual assessment and gross evaluation of all spines confirmed the results obtained from the bone-area measurements. Microquantitative computed tomography provided three-dimensional visual images of representative specimens, while histological staining of spine tissue displayed cellular evidence of bone formation. Conclusions: Results from this investigation confirm that the various isoforms of spp24 affect the bone-healing activity of rhBMP-2 in the rat spine fusion model. Thus, proteolytic modification of this protein is a likely mechanism for the regulation of BMP availability in the physiological environment. Future studies will define the roles of these proteins in controlling the activity of BMP5 and other members of the transforming growth factor-beta family of cytokines. This information will increase the understanding of normal bone-healing, allowing for the engineering of more effective orthopaedic treatment. [ABSTRACT FROM AUTHOR]

Bone morphogenetic binding peptide (BBP) is an 18.5 kDa fragment of a bone matrix protein peptide. A rat femoral defect model was used to test the effect of BBP combined with recombinant human bone morphogenetic protein-7 (rhBMP-7) to induced bone healing. Two doses of BBP (500 and 1000 µg) were tested with two doses of rhBMP-7 (2 and 5 µg), and the results were compared with a positive control (10 µg rhBMP-7). Bone healing was evaluated by radiology, manual palpation, microcomputed tomography, and histology. The high dose of 10 µg of rhBMP-7 resulted in a consistent 100% bone union rate and a mature histological appearance on histology, and was used as a positive control. When 1000 µg of BBP was combined with lower doses of BMP-7 (2 µg rhBMP-7 or 5 µg rhBMP-7) significant differences were seen in radiographic scores, manual palpation, and bone volume, when compared to 2 µg rhBMP-7 or 5 µg rhBMP-7 alone. The combination of 1000 µg of BBP and 5 µg rhBMP-7 also achieved 100% fusion rate, induced a larger amount of bone formation, and yielded similar maturity of bone marrow when compared with the high dosage 10 µg rhBMP-7 group. This study demonstrated that when combined together, BBP can enhance the bone healing of rhBMP-7. Improved healing imparted by the addition of BBP may result in lesser amounts of rhBMP-7 needed to achieve union in the clinical setting. © 2010 OrthopaedicResearchSociety.PublishedbyWileyPeriodicals, Inc.JOrthopRes29:753-759,2011 [ABSTRACT FROM AUTHOR]

Secreted phosphoprotein-24 kDa (spp24) is a bone morphogenetic protein (BMP)-binding protein isolated from bone. It exists in a number of size forms and is hypothesized to function as a BMP latency protein and/or a 'slow release' mechanism for BMPs involved in bone turnover and repair. We have examined the hypothesis that proteolytic modification of the C-terminus of spp24 affects its BMP-2-binding properties and bioactivity in the BMP-2-stimulated ectopic bone forming bioassay. Three different size forms of recombinant spp24 that correspond to predicted 18.1 kDa, 16.0 kDa, and 14.5 kDa proteolytic products were compared to full-length (fl) spp24. One of these forms (spp18.1) we hypothesize to be the protein which Urist initially, but apparently inaccurately, called 'BMP.' Only full-length spp24 completely inhibited BMP-2-induced bone formation. The 18.1 kDa truncated isoform of spp24 which we hypothesize to be Urist's protein did not. The inhibitory capacity of the proteins was correlated with their kinetic constants, assessed by surface plasmon resonance. At the highest, inhibitory, dose of spp24 and its derivatives, kd ('stability') best predicted the extent of ectopic bone formation whereas at the lowest dose, which was not inhibitory, ka ('recognition') best predicted the extent of ectopic bone formation. We conclude that proteolytic processing of spp24 affects the interaction of this protein with BMP-2 and this affects the function of the protein. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1200-1207, 2010 [ABSTRACT FROM AUTHOR]

Background: Demineralized bone matrix is an osteoinductive allograft derived from processed bone that is commonly mixed with autogenous bone in fusion procedures to treat diseases of the spine. An increasing number of demineralized bone matrix-based products are commercially available for spinal fusion procedures, but osteoinductive variability has been found not only across different products but also among production lots from the same demineralized bone matrix formulation. The purpose of this study was to assess the lot-to-lot variability across a single demineralized bone matrix-based product in terms of both extracted bone morphogenetic protein (BMP) concentrations (in vitro) and fusion performance in rats (in vivo). The goal was also to determine whether the in vitro measures could sufficiently and accurately predict the in vivo fusion performance of different demineralized bone matrix-based product lots. Methods: BMP-2 and BMP-7 were extracted from ten production lots of InterGro DBM Putty and quantified with use of ELISA (enzyme-linked immunosorbent assay). A posterolateral lumbar spinal fusion was performed on forty athymic rats with implantation of a demineralized bone matrix-based product. Fusion success was determined at eight weeks with use of radiographs and manual palpation of the segments. Logistic regression was used to determine the predictive abilities of BMPs. Results: Significant lot-to-lot variability was found in terms of both BMP concentrations (22 to 110 μg of BMP-2 per milligram of product and 44 to 125 μg of BMP-7 per milligram of product) and in vivo rates of fusion (0% to 75%; p < 0.04 for all). BMP-2 and BMP-7 concentrations correlated positively with each other across lots (r = 0.77, p < 0.0001). Most notably, extracted amounts of BMP-2 and BMP-7 each predicted in a dose-dependent manner the in vivo fusion performance in rats (R2 = 0.32, p < 0.01 for BMP-2, and R2 = 0.22, p < 0.009 for BMP-7). Conclusions: Assays for demineralized bone matrix-extracted BMP-2 and BMP-7 levels may be feasible and sufficient for predicting spinal fusion performance of individual production lots from the same demineralized bone matrix-based product. [ABSTRACT FROM AUTHOR]

The article highlights recent developments to the surgical treatment of spine diseases. It cited different updates to the surgical treatment of cervical spine pathology, spinal deformity surgery, surgery for spinal cord injury and surgical treatment for lumbar spine disorders. It also describes new developments in biologics related to the spine.

Concern regarding safety with respect to the clinical use of human bone morphogenetic protein-2 (BMP-2) has become an increasingly controversial topic. The role of BMP-2 in carcinogenesis is of particular concern. Although there have been many studies of this topic, the results have been contradictory and confusing. We conducted a systematic review of articles that are relevant to the relationship or effect of BMP-2 on all types of tumors and a total of 97 articles were included. Studies reported in these articles were classified into three major types: “expression studies”, “in vitro studies”, and “in vivo studies”. An obvious pattern was that those works that hypothesize an inhibitory effect for BMP-2 most often examined only the proliferative properties of the tumor cells. This subset of studies also contained an extraordinary number of contradictory findings which made drawing a reliable general conclusion impossible. In general, we support a pro-tumorigenesis role for BMP-2 based on the data from these in vitro cell studies and in vivo animal studies, however, more clinical studies should be carried out to help make a firm conclusion. [ABSTRACT FROM AUTHOR]

Several studies have shown that secreted phosphoprotein 24 kD (Spp24) inhibits tumor growth. However, the effects of spp24 on hepatocellular carcinoma are not quite clear. In this study, we observed the inhibitory effect of spp24 on hepatocellular carcinoma in vivo . A subcutaneous hepatocellular carcinoma mice model was established by using Hep G2 cells. After sacrifice at day 40, tumor growth was assessed and tumor cell apoptosis and tumor cells proliferation were assessed by TUNEL assay and immunochemical analysis, respectively. BMP2 slightly stimulated the subcutaneous tumor growth compared with the control. Spp24 significantly inhibited the tumor growth and also abolished the BMP2-induced tumor growth (p < 0.05). TUNEL assay and immunochemical analysis further showed that spp24 could enhance tumor cell apoptosis and inhibit cell proliferation (p < 0.01). Our data show that spp24 can inhibit the growth of hepatocellular carcinoma. Spp24 may have great potential for cancer treatment. [ABSTRACT FROM AUTHOR]

The emerging role of bone morphogenetic proteins (BMPs) in the initiation and progression of multiple cancers has drawn great attention in cancer research. In this study, we report that BMP-2 can promote the proliferation of the pancreatic tumor cell line, PANC-1. Secreted phosphoprotein 24 kD (Spp24), a BMP binding protein, did not affect the proliferation of the cells but promoted the apoptosis of the cells in vitro. In a xeneograft tumor model using PANC-1 cells, BMP-2 dramatically promoted tumor growth, while Spp24 not only abolished the effect of BMP-2, but also dramatically induced tumor shrinking when used alone. Activation of Smad1/5/8 participated in this process as demonstrated by immunohistochemical staining of phosphorylated Smad 1/5/8. We conclude that Spp24 can be developed into a therapeutic agent that could be employed in clinical situations where the inhibition of BMPs and related proteins is advantageous. [ABSTRACT FROM AUTHOR]

Background context Bone morphogenetic protein-2 (BMP-2) has been used to successfully promote spine fusion, but side-effects including nerve inflammation have been observed. Purpose To investigate the direct neurotoxic effects of BMP-2 and test the hypotheses that the use of BMP binding proteins, such as secreted phosphoprotein 24 kD (Spp24), can reduce or eliminate these effects. Study design In vitro experiments and in vivo analysis in a rodent model. Methods In vitro, dorsal root ganglion cells were cultured in the presence of BMP-2 with and without Spp24 and calcitonin gene-related peptide and Substance P, markers of neuroinflammation, were measured by immunohistochemistry. In vivo, rats underwent a left-sided laminotomy at L5 to expose the S1 nerve root and were randomized into four different groups according to the intervention at the laminotomy site: collagen sponge only (no BMP-2 or Spp24), BMP-2 in a collagen sponge only, BMP-2 in a collagen sponge+an empty collagen sponge to act as a barrier, and BMP-2 in a collagen sponge+Spp24 in a collagen sponge to act as a barrier. Functional evaluation was done using the Basso, Beattie, and Bresnahan scale and immunohistochemical analyses were performed using calcitonin gene-related peptide and Substance P staining. Results The neuroinflammatory effects of BMP-2 in vitro were ameliorated by the addition of Spp24. Similarly, in vivo, Spp24 reduced the expression of markers on neuroinflammation in animals treated with BMP-2 and also improved the function after BMP-2 administration. Conclusions These results confirm that BMP binding proteins have great potential as adjuvant therapies to limit BMP-2 related side-effects in spine surgery. [ABSTRACT FROM AUTHOR]

Study Design. Basic science rodent model of bone morphogenetic protein-2 (BMP-2) soft-tissue inflammation. Objective. This study investigated the anti-inflammatory effect of human dose equivalent (HDE) dexamethasone (DM) for treatment of BMP-2-related soft-tissue inflammation in a rodent model and suggests an appropriate dose for utilization in the clinical practice of spine surgeons. Summary of Background Data. BMP-2 is frequently used in spinal surgery to augment fusion. Yet, side effects of soft-tissue inflammation have been observed. DM decreases proinflammatory cytokine production and cellular immune response. However, the anti-inflammatory effects of HDE DM in a rodent model of BMP-2-associated soft-tissue inflammation have not been reported. Methods. Five, 10, and 15 mg of HDE DM were administered 3 times perioperatively to rodent cohorts receiving BMP-2 paraspinal implants and compared against BMP-2 only positive controls and phosphate buffer negative controls (n = 6 subjects per group). Histopathology, magnetic resonance imaging, and gross dissection were used as measures of cellular, edematous, and exudative inflammatory response. Serial killings were made on day 2 and day 7 postoperatively. Results. Magnetic resonance imaging volume rendering demonstrated inflammatory edema decreased by 49% from 605.4 mm³ to 304.03 mm³ in subjects treated with 5, 10, or 15 mg of HDE DM (P < 0.05). Histopathological analysis demonstrated inflammatory cross-sectional area decreased 28.8% from 1.84 mm² to 1.31 mm² in subjects treated with 5, 10 or 15 mg of HDE DM (P < 0.05). Immune cellular infiltration depth decreased 38.5% from 0.26 mm to 0.16 in subjects treated with 15 mg of HDE DM (P < 0.05). Gross anatomical inflammatory exudates were prevented in 100% of subjects treated with 10 or 15 mg of HDE DM (P < 0.05). Conclusion. Low-dose DM administration is effective in controlling the cellular inflammation and edema resulting from BMP-2. Ten or 15 mg of DM might be considered by spine surgeons for controlling the inflammation and edema seen in spine surgery with BMP-2. [ABSTRACT FROM AUTHOR]

Study Design. In vivo rodent model. Objective. Investigate the effect of systemic corticosteroid administration on soft-tissue inflammation after local delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2). Summary of Background Data. Corticosteroid use in cases of soft-tissue inflammation associated with the use of rhBMP-2 has been reported in clinical studies, but the effectiveness of its use and appropriate timing remain unclear. Methods. Absorbable collagen sponges were implanted with control or rhBMP-2 into the lumbar region of rats subcutaneously and intramuscularly. Four groups were studied: group I, control sponge only; group 2, BMP-2 sponge only; group III, BMP-2 sponge and preoperative intraperitoneal methylprednisolone (MPSS); group IV, BMP-2 sponge with MPSS given on day 2. Using magnetic resonance imaging, inflammation was assessed in terms of soft tissue edema volume at 0, 2, 4, and 7 days. Rats were sacrificed after 7 days for gross and histological analysis. Results. The peak mean intramuscular inflammatory volum occurred on day 2 in all groups. Group II (BMP-2 without MPSS) had a significantly higher peak mean inflammatory volume (405.46 mm³) on day 2 than that of groups I (266 mm³), III (278 mm³), and IV (291 mm³) mm (P = 0.001). No significant difference in intramuscular so tissue inflammation was observed between the control group and the groups receiving MPSS on clay 0 or day 2 at any time point. No differences in the area of inflammatory cell infiltrate surrounding the sponge was observed histologically, after sacrificing them, in groups treated with BMP-2. Conclusion. Systemic MPSS administration reduced soft tissue edema associated with rhBMP-2 as measured by magnetic resonance imaging, but no effect was observed on the histological area of inflammation. Further studies are required to elucidate if there is any benefit to the use of corticosteroid administration in reducing the area of inflammation associated with the use of rhBMP-2. [ABSTRACT FROM AUTHOR]

Abstract: Background context: Bone morphogenetic protein (BMP)-2 and BMP-7 are used to enhance bone formation in spine surgery, but the use of these materials is associated with side effects including inflammation, especially in the soft tissues of the neck. Bone morphogenetic protein–binding peptide (BBP) binds BMP-2 and BMP-7 and imparts a "slow-release" property to collagen carrier. Purpose: To test the hypothesis that the addition of BBP will reduce the soft-tissue inflammation induced by the implantation of BMP-2 and BMP-7 on a collagen sponge. Study design/setting: Prospective in vivo rodent model of inflammation. Methods: We implanted six different materials absorbed onto collagen sponges: absorbable collagen sponge (ACS) alone; BBP alone; recombinant human bone morphogenetic protein (rhBMP)-2 alone; rhBMP-2 plus BBP; rhBMP-7 alone; and rhBMP-7 plus BBP. Sponges were implanted bilaterally (subcutaneously [SC] and intramuscularly [IM]) into the backs of rats. Using magnetic resonance imaging, inflammation was assessed in terms of soft-tissue edema volume at 3 hours and at 2, 4, and 7 days. The animal subjects were killed on Day 7, and the dimensions of the inflammatory mass were measured manually in the case of SC tissue and those of the inflammatory zone were determined subsequently by microscopic examination in the case of muscle. Results: Both the SC and the IM soft-tissue edema volumes in the rhBMP-2 plus BBP and the rhBMP-7 plus BBP groups were significantly lower than those observed in the rhBMP-2 alone and rhBMP-7 alone groups. The edema volume associated with BBP alone was greater than that associated with ACS alone but less than that associated with the other treatment groups. The measurements of inflammatory masses and zone yielded similar results. Conclusions: Bone morphogenetic protein–binding peptide may reduce the inflammatory response associated with the use of rhBMP-2 and rhBMP-7 in a rodent model of inflammation and in a form that has previously been shown to enhance the activity of BMPs. These preliminary studies suggest that BBP may have the potential to be used in the future to improve healing and reduce soft-tissue swelling in surgical applications of BMPs. [Copyright &y& Elsevier]

The article focuses on a study which evaluated bone morphogenetic protein-binding peptide (BBP) interactions with bone morphogenetic proteins (BMP) in vitro and in vivo. Surface plasmon resonance was used to evaluate BBP binding with growth factors from the transforming growth factor-beta family. It is concluded that the use of BBP in conjunction with BMPs has the potential to provide satisfactory fusion outcomes.

The article discusses a study that compares the use of bone morphogenetic protein-2 (BMP-2) and bone marrow aspirate with allograft (BMAA) as alternatives to autograft in revision posterolateral lumbar spinal fusion (PLF). The review was made on 62 consecutive patients who underwent instrumented revision posterolateral spine fusion between January 2002 and December 2006. It suggests that rhBMP-2 offers an option to autogenous bone graft in single and multilevel revision in PLF while BMAA is a more cost-effective option as alternatives to autograft.

Background Context: Recombinant growth factors bone morphogenetic protein-2 (BMP-2) and BMP-7 are currently approved for human use but are associated with various adverse effects including ectopic bone formation and local inflammatory reaction. The development of alternative growth factors may help minimize the adverse effects of current osteoinductive therapeutics. Nell-1 (Nel-like molecule-1; Nel [a protein strongly expressed in neural tissue encoding epidermal growth factor like domain]) is a novel secretory molecule that appears to act more specifically on osteoblasts than the BMPs, which can act on multiple cell types. From a molecular point of view, Nell-1 is directly regulated by runt-related transcription factor 2 (Runx2/Cbfa1), a master regulatory gene controlling bone formation. Previous studies showed that Nell-1 accelerates osteogenic differentiation in vitro and calvarial bone formation in vivo. We hypothesize that Nell-1 may also effectively form bone in spinal fusion. Purpose: Our primary aim was to assess if direct adenoviral gene delivery with Nell-1 in a demineralized bone matrix (DBM) carrier can improve spinal fusion in a rat model. Because adenoviral vectors allow for sustained growth factor delivery, they were used for initial feasibility testing before protein studies. Study Design/setting: Two groups of 20 athymic rats underwent posterolateral intertransverse process spinal fusion at L4-L5 with implanted DBM carrier containing either adenovirus coding for Nell-1 (AdNell-1) or control, Lac Z (AdLacZ). No cells were implanted. The 20 rats were sacrificed at 6 weeks for evaluation of spinal fusion. Methods: All animals underwent Faxitron radiographs at 2, 4, and 6 weeks, manual spine palpation at 6 weeks, and high-resolution micro computerized tomography (microCT) at 6 weeks. Spinal fusion rate was assessed by: 1) 6-week Faxitron images; 2) manual palpation by three independent observers; 3) microCT; and 4) histology. New bone formation was assessed by hematoxylin-eosin and Masson trichrome staining on decalcified, coronally sectioned spine segments. Results: All differences achieved statistical significance. After 6 weeks, direct application of adenoviral Nell-1 in a DBM carrier achieved significantly higher rates of spinal fusion over Lac Z controls: 60% Nell-1 versus 20% Lac Z by manual palpation and 70% Nell-1 versus 20% Lac Z by microCT and histology. Histological assessment of bone quality and maturity revealed more mature, higher quality bone in all the Nell-1 treated specimens relative to Lac Z at 6 weeks. Conclusions: Spinal fusion is more accurately assessed by microCT and histology than manual palpation. Direct application of adenoviral Nell-1 in a DBM carrier achieved significantly higher rates of spinal fusion over Lac Z controls at 6 weeks. Direct application of adenoviral Nell-1 in a DBM carrier also achieved significantly higher rates of spinal fusion over other reports in the literature using direct adenoviral BMP application. Direct application of adenoviral BMP in an allograft carrier achieved 8% fusion for BMP-2 and 16% fusion for BMP-7 at 8 weeks. These results indicate that Nell-1 may be a potent osteoinductive molecule. In addition, the regulation of Nell-1 by the master bone regulatory gene, Runx2 suggests that Nell-1 may exert its effects more specifically in osteoblastic cells than BMPs which affect multiple cell types. Overall, Nell-1 may fulfil a current need for an osteoinductive factor. [ABSTRACT FROM AUTHOR]

Abstract: Background Context: Bone morphogenetic protein-2 (BMP-2) has been used extensively in recent years to enhance the process of spinal fusion. However, numerous side effects have been reported. This raises concerns regarding the safety of using this material in human beings. There are no published reports, that we are aware of, that demonstrate detectable levels of BMP-2 in human milk. Purpose: The purpose of this study was to determine the presence/absence of recombinant human bone morphogenetic protein-2 (rhBMP-2) in milk samples taken from a patient who underwent spinal surgery using rhBMP-2 shortly after delivering a child. Study Design/Setting: The study design comprises a case report dealing with analyzing milk from a patient who underwent spinal surgery using rhBMP-2 shortly after delivering a child. Methods: We report the analysis of milk samples from a patient who underwent spinal surgery using rhBMP-2 shortly after delivering a child to determine the presence/absence of rhBMP-2. The milk samples were taken before and after the spinal surgery. Enzyme-linked immunosorbent assays were performed repeatedly to the samples. Results: The standard curve for the assay had an r2 value of 0.9853 indicating an acceptable degree of statistical reliability. The dose range for the standard curve was 62.5 to 2,000 pg/mL. None of the samples had an optical density greater than that of the lowest standard. Conclusions: No rhBMP-2 was detected in human milk in this single case report. Although this result seemed promising, it did not eliminate the concern regarding the potential risk of rhBMP-2 on child development. We still need further studies including more cases to verify this conclusion. [Copyright &y& Elsevier]