Composite implant of native bovine bone morphogenetic protein (BMP), collagen carrier and biocoral in the treatment of resistant ulnar nonunions: report of five preliminary cases

Bone Morphogenic Protein for Upper Extremity Fractures: A Systematic Review

BACKGROUND

This review discusses success, time to healing, and complications of bone morphogenic proteins (BMPs) 7 and 2 in treating upper extremity nonunions.

METHODS

Systematic review identified 26 of 479 studies that met inclusion criteria. Publications described application of BMPs to acute and chronic upper extremity delayed unions/nonunions. Unions, complications, patient demographics, and fracture/healing patterns were pooled and analyzed.

RESULTS

Nonunions treated with BMP-7 (n=302) involved the humerus (64%), forearm (22%), clavicle (11%), and hand/wrist (3%), with prior surgical correction attempted in 84%. Nonunions treated with BMP-2 (n=96) involved the humerus (58%), hand/wrist (27%), forearm (14%), and clavicle (1%), with prior surgical correction attempted in all. Most nonunions (80%) were present for over 12 months before BMP application. Union rates of BMP-7 varied according to site: hand/wrist (95%), humerus (74%), forearm (29%), and clavicle (6.2%) nonunions achieved union as defined by study authors in 232 days (confidence interval=96-369, Q<0.001) on average. While not significant across studies, BMP-2 union rates were 71% of hand/wrist and 75% of humerus nonunions. Comparison of the BMPs demonstrates different proportions of success in humerus and hand/wrist fractures (P<.001) but not forearm fractures (P<.77) and longer time to radiographic union with BMP-7 (P<.011).

CONCLUSIONS

Most hand/wrist and humerus nonunions treated with BMP-7 and BMP-2 achieved union, with significant similarity among BMP-7 studies not observed in BMP-2 studies. Nonunions treated with BMP-7 have longer healing times yet similar complication rates compared with BMP-2. Overall, BMPs are an effective adjunct to fracture healing with acceptable complication profile.

Ternary regulation mechanism of Rhizoma drynariae total flavonoids on induced membrane formation and bone remodeling in Masquelet technique

CONTEXT

Rhizoma drynariae total flavonoids (RDTF) are used to treat fractures. CD31hiEmcnhi vessels induced by PDGF-BB secreted by osteoclast precursors, together with osteoblasts and osteoclasts, constitute the ternary regulatory mechanism of bone tissue reconstruction.

OBJECTIVE

This study aimed to determine whether RDTF can promote bone tissue remodeling and induce membrane growth in the rat Masquelet model and to explore its molecular mechanism based on the ternary regulation theory.

METHODS

Thirty-six SD rats were randomized to three groups: blank, induced membrane, and RDTF treatment (n = 12/group). The gross morphological characteristics of the new bone tissue were observed after 6 weeks. Sixty SD rats were also randomized to five groups: blank, induction membrane, low-dose RDTF, medium-dose RDTF, and high-dose RDTF (n = 12/group). After 4 weeks, immunohistochemistry and western blot were used to detect the expression of membrane tissue-related proteins. The mRNA expression of key factors of ternary regulation was analyzed by qRT-PCR.

RESULTS

RDTF positively affected angiogenesis and bone tissue reconstruction in the bone defect area. RDTF could upregulate the expression of key factors (PDGF-BB, CD31, and endomucin), VEGF, and HMGB1 mRNA and proteins in the ternary regulation pathway.

DISCUSSION AND CONCLUSION

Although the expected CD31hiEmcnhi vessels in the induction membrane were not observed, this study confirmed that RDTF could promote the secretion of angiogenic factors in the induced membrane. The specific mechanisms still need to be further studied.

Clinical application of bone morphogenetic proteins for bone healing: a systematic review

PURPOSE

This paper documents the existing evidence on bone morphogenetic proteins (BMPs) use for the treatment of bone fractures, non-union, and osteonecrosis, through a review of the clinical literature, underlying potential and limitations in terms of cost effectiveness and risk of complications.

METHODS

A systematic review was performed on the PubMed database using the following string: (bone morphogenetic proteins OR BMPs) and (bone repair OR bone regeneration) including papers from 2000 to 2016. The search focused on clinical trials dealing with BMPs application to favor bone regeneration in bone fractures, non-union, and osteonecrosis, in English language, with level of evidence I, II, III, and IV. Relevant data (type of study, number of patients, BMPs delivery material, dose, site, follow-up, outcome, and adverse events) were extracted and analyzed.

RESULTS

Forty-four articles met the inclusion criteria: 10 randomized controlled trials (RCTs), 7 comparative studies, 18 case series, and 9 case reports. rhBMP-2 was documented mainly for the treatment of fractures, and rhBMP-7 mainly for non-unions and osteonecrosis. Mixed results were found among RCTs and comparative papers: 11 reported positive results for BMPs augmentation, 3 obtained no significant effects, and 2 showed negative results. The only study comparing the two BMPs showed a better outcome with rhBMP-2 for non-union treatment.

CONCLUSION

Clinical evidence on BMPs use for the treatment of fractures, non-union, and osteonecrosis is still controversial, with the few available reports being mainly of low quality. While positive findings have been described in many studies, mixed results are still present in the literature in terms of efficacy and adverse events. The difficulties in drawing clear conclusions are also due to the studies heterogeneity, mainly in terms of different BMPs applied, with different concomitant treatments for each bone pathology. Therefore, further research with well-designed studies is needed in order to understand the real potential of this biological approach to favour bone healing.

A three-dimensional block structure consisting exclusively of carbon nanotubes serving as bone regeneration scaffold and as bone defect filler

Many recent studies have been conducted to assess the ability of composite materials containing carbon nanotubes (CNTs) with high bone affinity to serve as scaffolds in bone regenerative medicine. These studies have demonstrated that CNTs can effectively induce bone formation. However, no studies have investigated the usefulness of scaffolds consisting exclusively of CNTs in bone regenerative medicine. We built a three-dimensional block entity with maximized mechanical strength from multi-walled CNTs (MWCNT blocks) and evaluated their efficacy as scaffold material for bone repair. When MWCNT blocks containing recombinant human bone morphogenetic protein-2 (rhBMP-2) were implanted in mouse muscle, ectopic bone was formed in direct contact with the blocks. Their bone marrow densities were comparable to those of PET-reinforced collagen sheets with rhBMP-2. On day 1 and day 3, MC3T3-E1 preosteoblasts were attached to the scaffold surface of MWCNT blocks than that of PET-reinforced collagen sheets. They also showed a maximum compression strength comparable to that of cortical bone. Our MWCNT blocks are expected to serve as bone defect filler and scaffold material for bone regeneration.

Is there a role of coral bone substitutes in bone repair?

Xenogeneic bone graft materials are an alternative to autologous bone grafting. Among such implants, coralline-derived bone grafts substitutes have a long track record as safe, biocompatible and osteoconductive graft materials. In this review, we present the available literature surrounding their use with special focus on the commercially available graft materials. Corals thanks to their chemical and structural characteristics similar to those of the human cancellous bone have shown great potential but clinical data presented to date is ambiguous with both positive and negative outcomes reported. Correct formulation and design of the graft to ensure adequate osteo-activity and resorption appear intrinsic to a successful outcome.

Complications With the Use of BMP-2 in Scaphoid Nonunion Surgery

PURPOSE

In an effort to improve fracture healing and decrease the need for autologous bone graft, products such as recombinant human bone morphogenetic protein (rhBMP-2) have been developed and used in both spine and nonspine surgery. There is a paucity of literature regarding the use of rhBMP-2 in scaphoid nonunion surgery with very little reporting on the complications associated with its use. The objective of this study was to retrospectively review the complications documented for a case series of patients treated with revision fixation, bone graft, and rhBMP-2 in revision scaphoid nonunion surgery.

METHODS

We retrospectively reviewed 6 cases of scaphoid nonunion revision surgery comprising open reduction and internal fixation (ORIF). All cases were performed for persistent nonunion after a previous scaphoid ORIF. All patients were treated with revision screw fixation, bone graft, and rhBMP-2. Union was determined by computed tomography in all cases. Complications of nonunion, heterotopic bone formation, delayed wound healing, functional loss of motion, and need for revision surgery are reported.

RESULTS

Between 2011 and 2014, 6 cases in which rhBMP-2 was used in revision scaphoid nonunion surgery were identified. All patients had failed an initial attempt at ORIF after delayed union or nonunion. The time from injury to index ORIF ranged from 3 months to 4 years (mean, 24 months). Revision surgery with rhBMP-2 was performed at an average of 6 months from the index ORIF. Of the 6 cases, 2 had resultant persistent nonunion. Both underwent scaphoid excision and midcarpal arthrodesis. Four cases developed notable heterotopic ossification (one of which required revision surgery). One patient had a loss of functional motion after the revision surgery. There were no cases of delayed wound healing. Only one of the 6 patients healed without complications.

CONCLUSIONS

In this case series, the use of rhBMP-2 in scaphoid nonunions was associated with a higher complication rate than reported in previous studies. Surgeons performing off-label use of rhBMP-2 should be aware of the potential for complications including heterotopic ossification.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Bone Morphogenetic Proteins: structure, biological function and therapeutic applications

Bone Morphogenetic Proteins (BMPs) are multifunctional secreted cytokines, which belong to the TGF-β superfamily. These glycoproteins act as a disulfide-linked homo- or heterodimers, being potent regulators of bone and cartilage formation and repair, cell proliferation during embryonic development and bone homeostasis in the adult. BMPs are promising molecules for tissue engineering and bone therapy. The present review discusses this family of proteins, their structure and biological function, their therapeutic applications and drawbacks, their effects on mesenchymal stem cells differentiation, and the cell signaling pathways involved in this process.

Cochrane corner: bone morphogenetic protein (BMP) for fracture healing in adults

BACKGROUND

Delay in fracture healing is a complex clinical and economic issue for patients and health services.

OBJECTIVES

To assess the incremental effectiveness and costs of bone morphogenetic protein on fracture healing in fractures and nonunions compared with standards of care.

SEARCH STRATEGY

We searched The Cochrane Library (2008, Issue 4), MEDLINE, and other major health and health economics databases (to October 2008).

SELECTION CRITERIA

Randomized controlled trials (RCTs) and full or partial economic evaluations of bone morphogenetic protein for fracture healing in skeletally mature adults.

DATA COLLECTION AND ANALYSIS

All clinical and economic data were extracted by one author and checked by another.

Related Biological Research in the Interface between Bone Cement and Bone after Percutaneous Vertebroplasty

Percutaneous vertebroplasty (PVP) is widely used in the treatment of painful osteoporotic vertebral compression fractures with the injection of PMMA cement, and the controversy for PMMA damage to the osteoporotic bone tissue and to affect the fractures repairing never stops. 72 old female rabbits, each age 3.0~3.5 y, rabbits were assigned randomly to two groups of thirty-six each; PMMA cement were injected into vertebral body in rabbits via mimic PVP, sacrificed at 1 h, 24 h, 3 d, 7 d, 4 w, and 12 w. The expression VEGF and collagen type I, the tissue response, and repair reaction in the interface between PMMA and bone tissue were observed dynamically with RT-PCR and western blot technique; the osteocalcin expression were studied by immunohistochemistry. Compared with the control group, the expression of collagen I increased at 1 hour and was higher from 24 h to 3 d. From 4 weeks to 12 weeks after injection of PMMA. The expression of VEGF decreased at 1 hour and 24 hours, significantly increased at 3 days, decreased once again at 7 days, then increased significantly at 4-12 weeks. The osteocalcin expression continued to increase during 4 to 12 week. PMMA would not cause local bone permanent necrosis, and interface injury repairing cycle could be prolonged in a vertebroplasty.

Bone Substitute Effect on Vascularization and Bone Remodeling after Application of phVEGF165 Transfected BMSC

VEGF (vascular endothelial growth factor) promotes vascularization and remodeling of bone substitutes. The aim of this study was to examine the effect of distinct resorbable ceramic carriers on bone forming capacities of VEGF transfected bone marrow stromal cells (BMSC). A critical size defect of the radius in rabbits was filled either by a low surface scaffold called beta-TCP (tricalciumphsphate) or the high surface scaffold CDHA (calcium deficient hydroxy-apatite) loaded with autologous BMSC, which were either transfected with a control plasmid or a plasmid coding for phVEGF165. They were compared to unloaded scaffolds. Thus, six treatment groups (n = 6 in each group) were followed by X-ray over 16 weeks. After probe retrieval, the volume of new bone was measured by micro-CT scans and vascularization was assessed in histology. While only minor bone formation was found in both carriers when implanted alone, BMSC led to increased osteogenesis in both carriers. VEGF promoted vascularization of the scaffolds significantly in contrast to BMSC alone. Bone formation was increased in the beta-TCP group, whereas it was inhibited in the CDHA group that showed faster scaffold degradation. The results indicate that the interaction of VEGF transfected BMSC with resorbable ceramic carrier influences the ability to promote bone healing.

Allograft bone matrix versus synthetic bone graft substitutes

Autologous bone is used very often in the treatment of fresh fractures, delayed unions and non-unions. Alternatives have included allografts and in recent years also demineralized bone matrix. The growing availability of good synthetic bone grafts and their advantages in safety and avoiding donor-site morbidity are the reasons that these products are being used more and more. There are on the market a wide variety of substitutes with different capabilities. Nevertheless autologous bone graft is still considered as the gold standard and will be discussed here in that context. Osteoconductive, osteogenic and osteoinductive products will also be classified and their advantages and disadvantages described.

Bioglass as a carrier for reindeer bone protein extract in the healing of rat femur defect

Bioactive glasses have been developed as scaffolds for bone tissue engineering but combination with reindeer bone protein extract has not been evaluated. We investigated the effects of bone protein extract implants (5-40 mg dosages) with bioglass (BG) carrier on the healing of rat femur defects. Bioglass implants and untreated defects served as controls. All doses of extract increased bone formation compared with the control groups, and bone union was enhanced with doses of 10 mg or more. In comparison with untreated defect, mean cross-sectional bone area at the defect site was greater when implants with BG + 15 mg of extract or bioglass alone were used, bone density at the defect site was higher in all bioglass groups with and without bone extract, and the BG + 15 mg extract dosage marginally increased bone torsional stiffness in mechanical testing. Bioglass performed well as a carrier candidate for reindeer bone protein extract.

Use of bone morphogenetic proteins for augmentation of bone regeneration

A large body of preclinical and clinical data now documents that recombinant BMPs can be used for skeletal regeneration in humans and animals. Recombinant human BMP-2 and BMP-7 have been approved for use in human patients with long-bone fractures and nonunions and in patients undergoing lumbar fusion or various maxillofacial and dental regenerative procedures. These products have also been made available for veterinary use.

VEGF producing bone marrow stromal cells (BMSC) enhance vascularization and resorption of a natural coral bone substitute

Bone graft substitutes often exhibit poor bone regeneration in large defects because of inadequate vascularization. Studies have shown that if blood supply is compromised, application of osteogenic factors alone could not induce successful healing. This study was to evaluate the effects of vascular endothelial growth factor, which combined with a coralline scaffold, on vascularization, scaffold resorption and osteogenesis in a rabbit radius critical size defect model. The scaffold was either coated with a control-plasmid DNA (group 1), coated with VEGF-plasmid DNA (group 2), loaded with mesenchymal stem cells (BMSC) transfected with control plasmid (group 3) or with both stem cells and the VEGF plasmid (group 4). X-rays were taken every 4 weeks up to week 16, when animals were euthanized. The volume of new bone was measured by mu-CT scans and blood vessels were counted after anti-CD31 staining of endothelial cells. The results from the solitary VEGF- and VEGF-transfected cells (groups 2 and 4) demonstrated significantly enhanced vascularization, osteogenesis and resorption of the carrier when compared to the control group. The highest degree of osteogenesis was found when the carrier was loaded with BMSC (group 3), whereas VEGF-transfected cells led to the highest vascularization and fastest resorption of the bone substitute. Additionally, VEGF-transfected BMSC led to a more homogenous vascularization of the defect. The results indicate that VEGF can be a helpful factor to improve healing in large bone defects, in which bone substitutes will otherwise not be vascularized and replaced by fresh bone.

Comparative study between coral-mesenchymal stem cells-rhBMP-2 composite and auto-bone-graft in rabbit critical-sized cranial defect model

Tissue engineered bone has become a bone substitute for the treatment of bone defects in animal research. This study investigated the osteogenesis capacity of coral-MSCs-rhBMP-2 composite with the auto-bone-graft as control. Coral-MSCs-rhBMP-2 composite were fabricated by coral (as main scaffold), rhBMP-2 (as growth factor), and MSCs (cultured from iliac marrow as seed cells). Critical-sized defects (d = 15 mm) were made on forty rabbits crania and treated by different composite scaffolds: iliac autograft (n = 8), coral (n = 8), rhBMP-2/coral (n = 8), and MSCs/rhBMP-2/coral (n = 8). The defects were evaluated by gross observation, radiographic examination, histological examination, and histological fluorescence examinations after 8 and 16 weeks. The results showed that repair of bone defect was the least in coral group, and significant ingrowth of new bone formation and incorporation could be seen with 77.45% +/- 0.52% in radiopacity in MSCs/rhBMP-2/coral group, which was similar to that in iliac autograft group (84.61% +/- 0.56% in radiopacity). New bone formation in MSCs/rhBMP-2/coral group was more than that in rhBMP-2/coral group. And osteogenesis rate in MSCs/rhBMP-2/coral group (10.23 +/- 1.45 microm) was much faster than that in rhBMP-2/coral group (5.85 +/- 2.19 microm) according to histological fluorescence examination. Newly formed bone partly came from induced MSCs in composite scaffold according to bromodeoxyuridine immunohistochemical examination. These data implicated that MSCs could produce synergic effect with coral-rhBMP-2, and the tissue engineered bone of coral-MSCs-rhBMP-2 is comparable to auto-bone-graft for the repair of critical-sized bone defect.

Use of bone morphogenetic proteins in traumatology

An estimated 5-10% of all fractures show impaired healing, leading to delayed union, or non-union. Chemical, or physical methods to accelerate bone healing are of great interest to the orthopaedic and trauma community. Research over the last 20 years has established that successful fracture healing is steered by specific growth factors. Of these, the bone morphogenetic proteins (BMPs) are probably the most important. The signalling pathway of these proteins is tightly regulated, overseeing a finely orchestrated cascade of events that occur after a fracture. The promising results of BMPs in preclinical studies have recently cleared the way for their use in specific fractures, or non-unions in clinical practice. The purpose of this work is to give a brief overview of BMPs and to review the clinical data currently available on the use of BMPs in fracture healing.

Critical analysis and efficacy of BMPs in long bones non-union

Non-union of long bone fractures is considered as multifactorial. The management of this entity continues to be difficult often requiring multiple procedures with unpredictable results. Bone morphogenetic proteins (BMPs) are power agents being used in the clinical setting for a variety of pathological conditions where tissue regeneration is required. This article analyses the currently existing evidence of the efficacy of BMPs for the management of non-union of long bone fractures.

Prosthetic devices shaped as tubular chambers for the treatment of large diaphyseal defects by guided bone regeneration

Guided tissue regeneration is based on the hypothesis that the different tissues have unequal abilities to penetrate a wounded area during the healing process. The use of a device acting as a chamber allows the growth of a particular tissue and prevents the ingrowth of other tissues which impair the healing process. At the same time the chamber protects and maintains in situ the intrinsic growth factors so that they may perform their specific activity. Guided tissue regeneration currently plays a well-recognized role mostly in dentistry and peripheral nerve surgery but interesting perspectives have also opened up in orthopedics. Considering the possibility of using guided bone regeneration in the repair of diaphyseal bone defects, this updated survey highlights some critical points and pathways related to the state-of-the-art of this promising procedure, focusing particularly on the properties of the material to make the tubular chamber, the use of osteopromotive factors and the most appropriate animal model to be used for the experimental evaluation.

Effect of gamma irradiation on the osteoinductivity of morphogenetic protein extract from reindeer bone

BACKGROUND

Bone morphogenetic proteins (BMPs), which are capable of stimulating the production of new bone, must be sterilized before preclinical and clinical use to reduce the risk of infections and associated complications. In this study, we investigated the effects of gamma sterilization on the osteoinductivity of native reindeer BMP extract in the Balb/C mouse thigh muscle pouch model.

METHODS

5 mg of native reindeer BMP extract and 5 mg of bovine serum albumin were administered separately either in gelatine capsules or mixed with gelatine as injections. The dose of gamma irradiation was 4.1 Mrad. Unsterile capsules and injections served as controls. New bone formation was evaluated based on the incorporation of Ca45 and also radiographically 3 weeks after implantation.

RESULTS

Albumin-containing implants and injections did not induce new bone formation, as monitored in radiographs. Gamma sterilization did not reduce the osteoinductivity of native BMP extract in capsules, but a significant decrease in osteoinductivity--measured as area (50%) and Ca45 incorporation of new bone (27%)--was seen after injection. Gamma sterilization had no effect on the optical density of new bone induced by native BMP extract administered in capsules or by injection.

INTERPRETATION

We conclude that, as gamma irradiation did not reduce the osteoinductivity of reindeer BMP extract in gelatine capsules, this method appears to be suitable for sterilization of BMPs to be given in capsule form. Native reindeer BMP extract was more sensitive to irradiation in soluble collagen (gelatine) than BMP in gelatine capsules. This finding must be given serious consideration regarding treatment of patients, but the remaining activity may be sufficient for the induction of bone formation in preclinical and clinical situations.