Recombinant human bone morphogenetic protein-2 stimulates the osteogenic potential of the Schneiderian membrane: a histometric analysis in rabbits

Development of a new critical size defect model in the paranasal sinus and first approach for defect reconstruction-An in vivo maxillary bone defect study in sheep

Fractures of the paranasal sinuses often require surgical intervention. Persisting bone defects lead to permanent visible deformities of the facial contours. Bone substitutes for reconstruction of defects with simultaneous induction of new bone formation are not commercially available for the paranasal sinus. New materials are urgently needed and have to be tested in their future area of application. For this purpose critical size defect models for the paranasal sinus have to be developed. A ≥2.4 cm large bilateral circular defect was created in the anterior wall of the maxillary sinus in six sheep via an extraoral approach. The defect was filled with two types of an osteoconductive titanium scaffold (empty scaffold vs. scaffold filled with a calcium phosphate bone cement paste) or covered with a titanium mesh either. Sheep were euthanized after four months. All animals performed well, no postoperative complications occured. Meshes and scaffolds were safely covered with soft tissue at the end of the study. The initial defect size of ≥2.4 cm only shrunk minimally during the investigation period confirming a critical size defect. No ingrowth of bone into any of the scaffolds was observed. The anterior wall of the maxillary sinus is a region with low complication rate for performing critical size defect experiments in sheep. We recommend this region for experiments with future scaffold materials whose intended use is not only limited to the paranasal sinus, as the defect is challenging even for bone graft substitutes with proven osteoconductivity. Graphical abstract.

Evaluation of Bone Response to a Nano HA Implant Surface on Sinus Lifting Procedures: Study in Rabbits

The aim of this study was to evaluate the bone response to two different implant surfaces on sinus lift procedures in rabbits. Bilateral sinus lifting with inorganic bovine bone associated with collagen membrane and immediate implantation were performed in 16 rabbits. Custom mini-implants were randomly installed in the prepared sites: one side received a double acid-etched (DAE) surface and the other a nano-hydroxyapatite (NHA) surface. The animals were euthanized 30 and 60 days after surgery, and biopsies were collected for microtomographic and histomorphometric analysis. After 30 days, no intra- and inter-group statistical differences were observed in microtomographic analysis, while at 60 days, bone analysis showed statistically significant differences between groups (p < 0.05) for all the evaluated parameters. Histomorphometric analysis showed, after 30 days, mean % of Bone-to-Implant Contact (BIC) for DAE and NHA of 31.70 ± 10.42% vs. 40.60 ± 10.22% (p > 0.05), respectively; for % of Bone Area Fraction Occupancy (BAFO), mean values were 45.43 ± 3.597% for DAE and 57.04 ± 5.537% for NHA (p < 0.05). After 60 days, mean %BIC and %BAFO for DAE and NHA implants were statistically significant (p < 0.05). The NHA surface showed superior biological features compared to the DAE treatment, promoting higher bone formation around the implants in an experimental model of bone repair in a grafted area.

Core Ossification of Bone Morphogenetic Protein-2-Loaded Collagenated Bone Mineral in the Sinus

The objective of this study was to investigate in vitro release kinetics and ossification patterns of bone morphogenetic protein-2-soaked collagenated porcine bone mineral (BMP-2/CPBM) in rabbit sinuses. Release kinetics of BMP-2/CPBM was determined in vitro up to 56 days. In 16 rabbits, BMP-2/CPBM (BMP group) and CPBM alone (control group) were bilaterally grafted in both sinuses. After 4 (N = 8) and 12 (N = 8) weeks, radiographic and histologic analyses were performed. Approximately 40% of BMP-2 was released from CPBM during 3 days in vitro; release maintained at a reduced level until day 56. In vivo, new bone formation in BMP group was dominant at the center and decreased toward the borders of the sinus, while it mainly possessed close to the sinus membrane and basal bone in control group. At the center, significantly more new bone was found in BMP group compared to control group at 4 weeks (29.14% vs. 16.50%; p < 0.05). The total augmented volume of BMP group was significantly greater than control group at 4 (370.13 mm³ vs. 299.32 mm³) and 12 (400.40 mm³ vs. 290.10 mm³) weeks (p < 0.05). In conclusion, BMP-2/CPBM demonstrated a core ossification with a greater augmented volume and new bone formation in the center of the sinus compared to CPBM alone. Impact statement The center of the augmented maxillary sinus tends to show a slower and inferior new bone formation compared to the sites near the sinus membrane and basal bone. In this study, bone morphogenetic protein-2 (BMP-2) loaded onto collagenated porcine bone mineral (CPBM) resulted in a greater augmented volume and new bone formation at the center of the grafted sinus compared to CPBM alone. Therefore, BMP-2-added CPBM in maxillary sinus augmentation may potentially be beneficial to the clinicians, in terms of accelerating the new bone formation at the center area where the apical half of the implant fixture usually places.

Void space and long-term volumetric changes of maxillary sinus floor augmentation with comparison between hydroxyapatite soaked with bone morphogenetic protein 2 and anorganic bovine xenograft alone

PURPOSE

We hypothesized that the void volume after maxillary sinus floor augmentation (MSFA) with recombinant human bone morphogenetic protein-2 (rhBMP-2) would be larger than that without rhBMP-2, and filled with bone in the long term. The aim of this study was to analyze the occurrence of void space and long-term volumetric changes after MSFA with rhBMP-2 and hydroxyapatite (BMP-2/H).

MATERIAL AND METHODS

In 25 subjects, MSFA was performed with BMP-2/H (group I) or an anorganic bovine xenograft (group II). Computed tomography scans were taken twice, at 3 months (T1) and at least 24 months (T2) after surgery. Total volume (TV), bone volume (BV), and void volume (VV) were measured and analysed statistically.

RESULTS

While similar amounts of graft material were used, the TV was significantly larger in group I than in group II (p = 0.014). The VV showed a tendency to be larger in group I than in group II. VV reduction up to T2 was significantly greater in group I than in group II. Consequently, the BV at T2 was significantly greater in group I than in group II by 36% (p = 0.014).

CONCLUSION

This study showed that our hypothesis was valid. rhBMP-2 is effective for long-term bone regeneration after MSFA.

Long Noncoding RNA Sponges miR-454 to Promote Osteogenic Differentiation in Maxillary Sinus Membrane Stem Cells

OBJECTIVE

Although increasing evidence has shown that long noncoding RNAs (lncRNAs) play an important regulatory role in pluripotency and differentiation of mesenchymal stem cells, little is known about the role of lncRNA in maxillary sinus membrane stem cells (MSMSCs). The goal of this study was to investigate the expression profile and function of lncRNAs on osteogenic differentiation of MSMSCs.

MATERIALS AND METHODS

By using lncRNA microarray, we identify a novel osteogenesis differentiation-related lncRNA of MSMSCs (lncRNA-MODR). The functional role of lncRNA-MODR in regulating osteogenesis was evaluated by quantitative real-time polymerase chain reaction, western blot, and alizarin red staining. Bioinformatic analyses of the predicted target genes (gene ontology, pathway, and network analysis) were applied for further study of lncRNA-MODR.

RESULTS

We show that lncRNA-MODR is gradually upregulated during osteogenic differentiation. lncRNA-MODR overexpression upregulated, whereas lncRNA-MODR silencing decreased the expression of the osteogenic key marker, runt-related transcription factor 2 (RUNX2). In-depth analyses showed that lncRNA-MODR acts as a molecular sponge for microRNA-454 (miR-454) and that prevents RUNX2 from mi-454-mediated suppression.

CONCLUSION

The lncRNAs act as a competing endogenous RNA to sequester microRNA-454 (miR-454), leading to heightened RUNX2 expression and thus promotes osteogenesis of MSMSCs.

Proof-of-concept study of vertical augmentation using block-type allogenic bone grafts: A preclinical experimental study on rabbit calvaria

This study aimed to quantify the healing following vertical augmentation of allogenic bone blocks with/without recombinant human bone morphogenetic protein-2 (rhBMP-2) on rabbit calvaria. Experiments were performed using allogenic bone blocks which were grafted bilaterally with or without rhBMP-2 on 20 rabbit calvaria, and these animals were divided to four groups according to the use of rhBMP-2 and healing periods (2 and 8 weeks; n = 10 in each group). Onlay-type bone blocks (8 mm in diameter and 5 mm high) were fixed with a self-tapping screw after removing the cortex in the control group, and the same protocol was applied with the addition of soaking the bone blocks with rhBMP-2 for 15 min in the test group. Radiographic and histologic analyses were performed after 2 or 8 weeks to evaluate the volumetric stability and bone regeneration within the grafted area. The radiographic analysis revealed that the height of the allogenic bone block decreased but its volume was maintained from 2 to 8 weeks in both the control and test groups. The histologic results demonstrated a statistically significant increase in new bone area in the test group, especially in the lower region adjacent to the preexisting calvarial floor. The amount of newly formed bone in all regions of the augmented bone blocks in both the control and test groups was greater at 8 weeks than at 2 weeks. In conclusion, the vertically grafted allogenic bone block maintained its volume with new bone formation, and this was accelerated by the addition of rhBMP-2. These findings indicate that allogenic bone block soaked with rhBMP-2 could be a useful candidate biomaterial for vertical augmentation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2700-2707, 2018.

Bone Regeneration Using N-Methyl-2-pyrrolidone as an Enhancer for Recombinant Human Bone Morphogenetic Protein-2 in a Rabbit Sinus Augmentation Model

The aim of this study was to determine whether N-methyl-2-pyrrolidone (NMP) can decrease the dose of recombinant human bone morphogenetic protein-2 (rhBMP-2) in sinus augmentation of rabbits. In each of 15 rabbits, 2 sinuses were randomly grafted using 1 of 3 treatment modalities: (i) biphasic calcium phosphate (BCP; control), (ii) rhBMP-2-coated BCP (BMP), or (iii) rhBMP-2-coated BCP soaked in NMP solution (BMP/NMP). The rabbits were sacrificed 2 weeks postoperatively. Histologic and histomorphometric analyses were performed. Bone formation in all groups was predominantly located close to the access window and the lateral walls. Newly formed bone within the total augmented area (NB_TA) was greatest in BMP/NMP (1.94 ± 0.69 mm²), followed by BMP (1.50 ± 0.72 mm²) and BCP (1.28 ± 0.52 mm²) (P > 0.05). In the center of the augmentation (NB_{ROI_C}) and the area close to the sinus membrane (NB_{ROI_M}), BMP/NMP produced the largest area of NB (NB_{ROI_C}: 0.10 ± 0.11 mm²; NB_{ROI_M}: 0.17 ± 0.08 mm²); the corresponding NB values for BCP were 0.05 ± 0.05 mm² and 0.08 ± 0.09 mm², respectively (P > 0.05 for all comparisons). The effect of NMP on bone regeneration was inconsistent between the specimens. Adding NMP as an adjunct to rhBMP-2-coated BCP produced inconsistent effects on bone regeneration, resulting in no significant benefit compared to controls.

Sinus augmentation using rhBMP-2-loaded synthetic bone substitute with simultaneous implant placement in rabbits

PURPOSE

The aim of this study was to determine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2)-loaded synthetic bone substitute on implants that were simultaneously placed with sinus augmentation in rabbits.

METHODS

In this study, a circular access window was prepared in the maxillary sinus of rabbits (n=5) for a bone graft around an implant (Ø 3×6 mm) that was simultaneously placed anterior to the window. Synthetic bone substitute loaded with rhBMP-2 was placed on one side of the sinus to form the experimental group, and saline-soaked synthetic bone substitute was placed on the other side of the sinus to form the control group. After 4 weeks, sections were obtained for analysis by micro-computed tomography and histology.

RESULTS

Volumetric analysis showed that the median amount of newly formed bone was significantly greater in the BMP group than in the control group (51.6 mm³ and 46.6 mm³, respectively; P=0.019). In the histometric analysis, the osseointegration height was also significantly greater in the BMP group at the medial surface of the implant (5.2 mm and 4.3 mm, respectively; P=0.037).

CONCLUSIONS

In conclusion, an implant simultaneously placed with sinus augmentation using rhBMP-2-loaded synthetic bone substitute can be successfully osseointegrated, even when only a limited bone height is available during the early stage of healing.

Increased osteoinductivity and mineralization by minimal concentration of bone morphogenetic protein-2 loaded onto biphasic calcium phosphate in a rabbit sinus

Purpose

The purpose of the present study was to evaluate the effectiveness of a minimal concentration of bone morphogenetic protein-2 (BMP-2) in terms of quantitative and qualitative analyses of newly formed bone in a rabbit maxillary sinus model.

Methods

In 7 rabbits, sinus windows were prepared bilaterally. Biphasic calcium phosphate (BCP) loaded with 0.05 mg/mL BMP-2 was grafted into one sinus (the BMP group) and saline-soaked BCP was placed into the other (the control group) in each animal. The animals were allowed an 8-week healing period before being sacrificed. Specimens including the augmented area and surrounding tissues were then removed and evaluated both radiographically and histologically.

Results

There was a difference in the mineralization of new bone between the groups. In the BMP group, the greater part of the new bone consisted of mature lamellar bone with an evident trabecular pattern, whereas the control group showed mostly woven bone, consisting only partially of lamellar bone. Histometrically, the area of new bone was significantly greater (4.55±1.35 mm² vs. 2.99±0.86 mm²) in the BMP group than in the control group (P<0.05); however, the total augmentation volumes were not significantly different between the groups.

Conclusions

Within the limitations of this study, it can be suggested that a minimal concentration of BMP-2 (0.05 mg/mL) had an osteoinductive effect with accelerated mineralization in a rabbit sinus model using a BCP carrier.

Bone formation around rhBMP-2-coated implants in rabbit sinuses with or without absorbable collagen sponge grafting

PURPOSE

The purpose of this study was to evaluate bone formation around recombinant human bone morphogenetic protein (rhBMP-2)-coated implants placed with or without absorbable collagen sponge (ACS) in rabbit maxillary sinuses.

METHODS

The Schneiderian membrane was elevated and an implant was placed in 24 sinuses in 12 rabbits. The space created beneath the elevated membrane was filled with either blood (n=6) or ACS (n=6). In the rabbits in which this space was filled with blood, rhBMP-2-coated and non-coated implants were alternately placed on different sides. The resulting groups were referred to as the BC and BN groups, respectively. The AC and AN groups were produced in ACS-grafted rabbits in the same manner. Radiographic and histomorphometric analyses were performed after eight weeks of healing.

RESULTS

In micro-computed tomography analysis, the total augmented volume and new bone volume were significantly greater in the ACS-grafted sinuses than in the blood-filled sinuses (P<0.05). The histometric analysis showed that the areas of new bone and bone-to-implant contact were significantly larger in the AC group than in the AN group (P<0.05). In contrast, none of the parameters differed significantly between the BC and BN groups.

CONCLUSIONS

The results of this pilot study indicate that the insertion of ACS after elevating the Schneiderian membrane, simultaneously with implant placement, can significantly increase the volume of the augmentation. However, in the present study, the rhBMP-2 coating exhibited limited effectiveness in enhancing the quantity and quality of regenerated bone.

Reduction of Adipose Tissue Formation by the Controlled Release of BMP-2 Using a Hydroxyapatite-Coated Collagen Carrier System for Sinus-Augmentation/Extraction-Socket Grafting

The effects of hydroxyapatite (HA)-coating onto collagen carriers for application of recombinant human bone morphogenetic protein 2 (rhBMP-2) on cell differentiation in vitro, and on in vivo healing patterns after sinus-augmentation and alveolar socket-grafting were evaluated. In vitro induction of osteogenic/adipogenic differentiation was compared between the culture media with rhBMP-2 solution and with the released rhBMP-2 from the control collagen and from the HA-coated collagen. Demineralized bovine bone and collagen/HA-coated collagen were grafted with/without rhBMP-2 in sinus-augmentation and tooth-extraction-socket models. Adipogenic induction by rhBMP-2 released from HA-coated collagen was significantly reduced compared to collagen. In the sinus-augmentation model, sites that received rhBMP-2 exhibited large amounts of vascular tissue formation at two weeks and increased adipose tissue formation at eight weeks; this could be significantly reduced by using HA-coated collagen as a carrier for rhBMP-2. In extraction-socket grafting, dimensional reduction of alveolar ridge was significantly decreased at sites received rhBMP-2 compared to control sites, but adipose tissue was increased within the regenerated socket area. In conclusion, HA-coated collagen carrier for Escherichia coli-derived rhBMP-2 (ErhBMP-2) may reduce in vitro induction of adipogenic differentiation and in vivo adipose bone marrow tissue formation in bone tissue engineering by ErhBMP-2.

Investigation of multipotent postnatal stem cells from human maxillary sinus membrane

Maxillary sinus membrane (MSM) elevation is a common surgical technique for increasing bone height in the posterior maxilla prior to dental implant placement. However, the biological nature of bone regeneration in MSM remains largely unidentified. In this study, MSM tissue was obtained from 16 individuals during orthognathic surgery and used to isolate MSM stem cells (MSMSCs) by single-colony selection and STRO-1 cell sorting. The cell characteristics in terms of colony-forming ability, cell surface antigens, multi-differentiation potential and in vivo implantation were all evaluated. It was found that MSMSCs were of mesenchymal origin and positive for mesenchymal stem cell (MSC) markers such as STRO-1, CD146, CD29 and CD44; furthermore, under defined culture conditions, MSMSCs were able to form mineral deposits and differentiate into adipocytes and chondrocytes. When transplanted into immunocompromised rodents, MSMSCs showed the capacity to generate bone-like tissue and, importantly, maintain their MSC characteristics after in vivo implantation. These findings provide cellular and molecular evidence that MSM contains stem cells that show functional potential in bone regeneration for dental implant.

A high concentration of recombinant human bone morphogenetic protein-2 induces low-efficacy bone regeneration in sinus augmentation: a histomorphometric analysis in rabbits

OBJECTIVES

The aim of the study was to elucidate the efficacy of bone regeneration at the early stage of healing in rabbit sinuses grafted with a biphasic calcium phosphate (BCP) carrier soaked in a high concentration of recombinant human bone morphogenetic protein-2 (rhBMP-2).

MATERIALS AND METHODS

Both maxillary sinuses of eight male rabbits were used. The sinus on one side (assigned randomly) was grafted with BCP loaded with rhBMP-2 (1.5 mg/ml; test group) using a soaking method, while the other was grafted with saline-soaked BCP (control group). After a 2-week healing period, the sinuses were analyzed by micro-computed tomography and histomorphometry.

RESULTS

The total augmented area and soft tissue space were significantly larger in the test group than in the control group, whereas the opposite was true for the area of residual material and newly formed bone. Most of the new bone in the test group was localized to the Schneiderian membrane (SM), while very little bone formation was observed in the window and center regions of the sinus. New bone was distributed evenly in the control group sinuses.

CONCLUSION

Within the limitations of this study, it appeared that application of a high concentration of rhBMP-2 soaked onto a BCP carrier inhibited bone regeneration from the pristine bone and increased soft tissue swelling and inflammatory response at the early healing stage of sinus augmentation, although osteoinductive potential was found along the SM.

Lumbar interbody fusion with porous biphasic calcium phosphate enhanced by recombinant bone morphogenetic protein-2/silk fibroin sustained-released microsphere: an experimental study on sheep model

Biphasic calcium phosphate (BCP) has been investigated extensively as a bone substitute nowadays. However, the bone formation capacity of BCP is limited owing to lack of osteoinduction. Silk fibroin (SF) has a structure similar to type I collagen, and could be developed to a microsphere for the sustained-release of rhBMP-2. In our previous report, bioactivity of BCP could be enhanced by rhBMP-2/SF microsphere (containing 0.5 µg rhBMP-2) in vitro. However, the bone regeneration performance of the composite in vivo was not investigated. Thus, the purpose of this study was to evaluate the efficacy of BCP/rhBMP-2/SF in a sheep lumbar fusion model. A BCP and rhBMP-2/SF microsphere was developed, and then was integrated into a BCP/rhBMP-2/SF composite. BCP, BCP/rhBMP-2 and BCP/rhBMP-2/SF were implanted randomly into the disc spaces of 30 sheep at the levels of L1/2, L3/4 and L5/6. After sacrificed, the fusion segments were evaluated by manual palpation, CT scan, biomechanical testing and histology at 3 and 6 months, respectively. The composite demonstrated a burst-release of rhBMP-2 (39.1 ± 2.8 %) on the initial 4 days and a sustained-release (accumulative 81.3 ± 4.9 %) for more than 28 days. The fusion rates, semi-quantitative CT scores, fusion stiffness in bending in all directions and histologic scores of BCP/rhBMP-2/SF were significantly greater than BCP and BCP/rhBMP-2 at each time point, respectively (P < 0.05). These findings indicate that the SF microspheres containing a very low dose of rhBMP-2 improve fusion in sheep using BCP constructs.

Tissue engineering for bone regeneration and osseointegration in the oral cavity

OBJECTIVE

The focus of this review is to summarize recent advances on regenerative technologies (scaffolding matrices, cell/gene therapy and biologic drug delivery) to promote reconstruction of tooth and dental implant-associated bone defects.

METHODS

An overview of scaffolds developed for application in bone regeneration is presented with an emphasis on identifying the primary criteria required for optimized scaffold design for the purpose of regenerating physiologically functional osseous tissues. Growth factors and other biologics with clinical potential for osteogenesis are examined, with a comprehensive assessment of pre-clinical and clinical studies. Potential novel improvements to current matrix-based delivery platforms for increased control of growth factor spatiotemporal release kinetics are highlighting including recent advancements in stem cell and gene therapy.

RESULTS

An analysis of existing scaffold materials, their strategic design for tissue regeneration, and use of growth factors for improved bone formation in oral regenerative therapies results in the identification of current limitations and required improvements to continue moving the field of bone tissue engineering forward into the clinical arena.

SIGNIFICANCE

Development of optimized scaffolding matrices for the predictable regeneration of structurally and physiologically functional osseous tissues is still an elusive goal. The introduction of growth factor biologics and cells has the potential to improve the biomimetic properties and regenerative potential of scaffold-based delivery platforms for next-generation patient-specific treatments with greater clinical outcome predictability.

Pre-clinical evaluation of the osteogenic potential of bone morphogenetic protein-2 loaded onto a particulate porcine bone biomaterial

AIM

The objective of study was to determine the osteogenic potential of bone morphogenetic protein-2 (BMP-2) loaded onto a particulate porcine bone mineral (PBM) biomaterial using a sinus augmentation model.

METHODS

Release kinetics of BMP-2/PBM was determined in vitro. Eight rabbits received BMP-2/PBM or PBM alone into contra-lateral sinus sites. The animals were killed following a 2-week healing interval for micro-CT and histometrical analysis.

RESULTS

Approximately 40% of the BMP-2 was released from PBM over the first 3 days in vitro; release maintained at a reduced level through day 21. In vivo, total augmented implant volume did not differ significantly between treatments. However, local bone formation was enhanced in the BMP-2/PBM group compared with PBM control (10.5% versus 6.6%; p = 0.03), specifically in the central aspect of the PBM implant (14.2% versus 5.5%; p < 0.01) and adjoining the Schneiderian membrane (11.9% versus 5.0%; p < 0.05). There were no significant overall differences in residual biomaterial and fibrovascular tissue.

CONCLUSION

Bone morphogenetic protein-2 enhanced local bone formation in the rabbit maxillary sinus model following implantation using a PBM carrier.

Controlled release of BMP-2 using a heparin-conjugated carrier system reduces in vivo adipose tissue formation

There is growing concern about unwanted effects associated with the clinical use of recombinant human bone morphogenetic protein-2 (rhBMP-2) at high concentrations, including cyst-like bone formation and excessive fatty marrow formation. We, therefore, evaluated the induction of mineralized/adipose tissue formation and the bone-healing pattern associated with the controlled release of E. coli-derived rhBMP-2 (ErhBMP-2) by a heparin-conjugated fibrin (HCF) system using ectopic and orthotopic in vivo models, respectively. In the ectopic transplantation model, mineralized tissue formed at the most superficial layer of the transplanted area and on the surfaces of grafted materials, and most of the interstitial space within the transplanted area was filled with excessive adipose tissue specifically at sites that received ErhBMP-2. However, sites that received ErhBMP-2 and HCF showed significantly increased mineralized tissue formation and decreased adipose tissue formation compared to the normal fibrin system with ErhBMP-2. In the orthotopic (calvarial defect) model, controlled release of ErhBMP-2 induced by HCF significantly reduced adipose tissue formation within the defect area compared to the clinically approved absorbable collagen sponge. From these results, it can be concluded that the use of a HCF system loaded with ErhBMP-2 may reduce adipose tissue formation and enhance mineralized tissue formation.

Low-dose recombinant human bone morphogenetic protein-2 to enhance the osteogenic potential of the Schneiderian membrane in the early healing phase: in vitro and in vivo studies

PURPOSE

The objectives of this study were to confirm the osteogenic potential of the Schneiderian membrane and to elucidate the early healing pattern of low-dose recombinant human bone morphogenetic protein-2 (rhBMP-2)-coated biphasic calcium phosphate (BCP).

MATERIALS AND METHODS

The osteogenic potential of the Schneiderian membrane and enhancement by rhBMP-2 were evaluated by in vitro analysis. RhBMP-2-coated BCP (experimental group) and BCP soaked with saline (control group) were applied to the maxillary sinus in rabbits. After 2 weeks, micro-computed tomographic and histometric analyses were performed.

RESULTS

Enhanced osteogenic potential was found when cells from the Schneiderian membrane were treated with rhBMP-2. Micro-computed tomographic analysis showed that the total augmented volume was significantly larger in the experimental group. Different healing patterns were observed in 3 regions, although the area of new bone did not differ significantly. Although more newly formed bone appeared, particularly along the Schneiderian membrane in the experimental group, the difference was not statistically significant.

CONCLUSIONS

RhBMP-2 enhanced the osteogenic potential of the Schneiderian membrane in vitro. However, low-dose rhBMP-2-coated BCP failed to exert a statistically significant effect in vivo, although it appeared to be effective in sinus augmentation specifically for the volumetric increase in the early phase.

Sinus augmentation using BMP-2 in a bovine hydroxyapatite/collagen carrier in dogs

AIM

The objective of this study was to determine the efficacy of bone morphogenetic protein 2 (BMP-2) in a bovine hydroxyapatite/collagen (BHC) carrier to augment bone formation in a canine nasal sinus model.

METHODS

Eight mongrel dogs, approximately 12 months old and 30 kg in weight were used. Following preparation of bilateral sinus access windows, BHC alone (control) or loaded with E. coli-derived BMP-2 at 0.1 mg/ml was implanted in four animals, and BHC loaded with E. coli-derived BMP-2 at 0.5 and 1.5 mg/ml was implanted in four animals. The animals were euthanized at 20 weeks when block sections were obtained for micro-computed tomography and histometric analyses.

RESULTS

Total augmented volumes did not differ significantly between groups. Histometric analysis showed significantly enhanced bone formation for the BMP-2 groups compared with control.

CONCLUSION

BMP-2 in a BHC carrier, even at the low 0.1-mg/ml concentration, induces osteogenic activity, enhancing local bone formation in a canine sinus model.