The reaction of the dura to bone morphogenetic protein (BMP) in repair of skull defects

Investigation of the Effects of Ozon and Propolis on the Healing of Bone Defects: An Experimental Study

BACKGROUND/AIM

This study explores the effects of ozone and propolis on the healing of critically sized bone defects at both the histologic and molecular levels, and the locations and concentrations of osteopontin and osteonectin during healing; both proteins play roles during bone healing.

MATERIALS AND METHODS

This study used 56 adult male Sprague-Dawley rats of an average weight of 350 g, divided into four groups of 14: a control group, a topical ozone group (O), a topical ozone + systemic propolis (O + PO) group, and a systemic propolis group (PO). Seven rats from each group were sacrificed at the end of week 4 and the other seven at the end of week 6. Tissues were subjected to histologic and immunohistochemical examinations in a fixative solution. The results were analyzed using the statistical software package SPSS 23 (Statistical Package for the Social Sciences-IBM). Results were considered significant at the 95% confidence level (P<0.05).

RESULTS

Graft sections were immunostained for osteonectin. Staining was low in the control group but moderate in the other three groups; the differences were significant. The three experimental groups did not differ significantly. Graft sections were also immunostained for osteonectin. At 4 weeks, staining was low in the control group but moderate in the other 3 groups. At 6 weeks, stronger staining was apparent in the 3 experimental groups. At both 4 and 6 weeks, the differences between the control and experimental groups were significantly different, but the differences among the experimental groups were not.

CONCLUSION

The authors' results are compatible with the literature. Ozone and propolis, given separately or together, improved bone healing, increased bone formation, and reduced bone destruction. However, further research is required.

Evaluation of Biocomposite Cements for Bone Defect Repair in Rat Models

Repairing or reconstructing significant bone defects is typically challenging. In the present study, two composite cements were used as scaffolds in a sub-critical femoral defect in rats. A control group and two experimental batches were used to compare the outcomes. This research aimed to investigate the osteogenic potential and toxicological tolerance of the bioproducts through histopathology and computed tomography imaging analysis at 14, 28, 56, and 90 days post-implantation. The biomaterials used in the investigation consisted of a 65% bioactive salinized inorganic filler and a 25% weight organic matrix. The organic part of the biomaterial was composed of Bis-GMA (bisphenol A-glycidyl methacrylate), UDMA (urethane dimethacrylate), HEMA (2-Hydroxyethyl methacrylate), and TEGDMA (triethylene glycol dimethacrylate), while the inorganic filler was composed of silica, barium glass, hydroxyapatite, and fluor aluminosilicate glass. The first findings of this research are encouraging, revealing that there is a slight difference between the groups treated with biomaterials, but it might be an effective approach for managing bone abnormalities. Material C1 exhibited a faster bone defect healing time compared to material C2, where bone fractures occurred in some individuals. It is unclear if the fractures were caused by the presence of the biomaterial C2 or whether additional variables were to blame. By the end of the research, the mice appeared to tolerate the biomaterials without exhibiting any inflammatory or rejection responses.

In Vivo Evaluation of Regenerative Osteogenic Potential Using a Human Demineralized Dentin Matrix for Dental Application

BACKGROUND

The use of a demineralized dentin matrix (DDM) has garnered substantial importance in dentistry. This study was carried out to evaluate the osteoinductive performance of DDM in comparison to nano-hydroxyapatite (n-HA) on calvarial critical-sized bone defect.

METHODS

Two critical-sized defects (CSDs) were bilaterally trephined in the calvarium of sixteen healthy white rabbits. The rabbits were categorized into four groups: in group 1, the defect was left empty; in group 2, defects were filled with sodium alginate (SA) hydrogel as a sole material; in group 3, defects were treated with nano-hydroxyapatite hydrogel (NHH); in group 4, defects were treated using demineralized dentin matrix hydrogel (DDMH). Histological and immunohistochemical analyses were carried out to evaluate the total areas of newly formed bone.

RESULTS

The DDMH group showed that new woven bone tissue progressively bridged the defect area while there was no bone in the control group. Collagen expression was significantly different in the DDMH- and NHH-treated groups compared to in the SA group at 4 and 8 weeks (p < 0.01). OCN expression was significantly higher in the DDMH group in comparison to in the NHH or SA groups at 8 weeks (p < 0.01).

CONCLUSIONS

The DDMH group exhibited significantly higher levels of new bone formation compared to the NHH group at both 4 and 8 weeks post-surgically.

BMP-2 promotes fracture healing by facilitating osteoblast differentiation and bone defect osteogenesis

OBJECTIVE

To investigate the role of bone morphogenetic protein-2 (BMP-2) in promoting fracture healing in animal models.

METHODS

Mouse models with muscle bag heterotopic osteogenesis (HO) were divided into a HO control group (not implanted with 250 μg rhBMP-2 bone repairing material), and a HO observation group (implanted with 250 μg rhBMP-2 bone repairing material); while rat models with bone defect (BD) were divided into a BD control group (not implanted with 250 μg rhBMP-2 bone repairing material) and a BD observation group (implanted with 250 μg rhBMP-2 bone repairing material). At 4 weeks after HO establishment, the new bone formation at the operation site was observed through visual inspections and X-ray scanning. The content of serum alkaline phosphatase (ALP) was detected by automatic biochemical analyzer. The formation of new bone at the operative sites was observed by Hematoxylin and eosin staining and Masson staining. At 0, 2, 4 and 8 weeks after operation, the growth of the defect area and its surrounding callus were observed by X-ray scanning. At 4 and 8 weeks after bone defect establishment in the mouse models, the histological changes and osteogenesis of the bone defect site were observed.

RESULTS

The heterotopic osteogenesis experiment showed that at 4 weeks after operation, the mass at the muscle bag in the HO observation group became larger in contrast to the HO control group. X-ray scanning showed that there was obvious irregular bone shadow at the back muscle bag of mice from the HO observation group. The content of serum ALP in the HO observation group was significantly higher than that in the HO control group (all P<0.05). The muscle pocket in the HO observation group showed higher ectopic osteogenic activity comparing with the HO control group. Histological staining showed that bone tissue structure was visible in the newly regenerated bone, forming bone trabeculae and bone marrow tissue. Under the microscope, a large number of osteoblasts arranged neatly in a cubic shape presented at the edge of the new bone, and there were bone lacunae formed, and the bone tissue was in a relatively mature stage. In the rat bone defect models, X-ray scanning showed that the high-density development area was further increased. There was a large amount of callus formation in the bone defect area of the BD observation group, while the BD control group still had no high-density development. At 8 weeks after operation, the high-density development area decreased, indicating that there was partial absorption of callus, while there was still no high-density development in the BD control group. The callus of the bone defect area in the BD observation group was reduced and the defect area was gradually repaired, while the bone defect in the BD control group was still obvious and the bone repair was not completed.

CONCLUSIONS

BMP-2 could promote osteoblast differentiation and bone defect osteogenesis in vivo. Thus, it is worthy of clinical application.

Antimicrobial and Pro-Osteogenic Coaxially Electrospun Magnesium Oxide Nanoparticles-Polycaprolactone /Parathyroid Hormone-Polycaprolactone Composite Barrier Membrane for Guided Bone Regeneration

Introduction

An antibacterial and pro-osteogenic coaxially electrospun nanofiber guided bone regeneration (GBR) membrane was fabricated to satisfy the complicated and phased requirements of GBR process.

Methods

In this study, we synthesize dual-functional coaxially electrospun nanofiber GBR membranes by encapsulating parathyroid hormone (PTH) in the core layer and magnesium oxide nanoparticles (MgONPs) in the shell layer (MgONPs-PCL/PTH-PCL). Herein, the physicochemical characterization of MgONPs-PCL/PTH-PCL, the release rates of MgONPs and PTH, and antibacterial efficiency of the new membrane were evaluated. Furthermore, the pro-osteogenicity of the membranes was assessed both in-vitro and in-vivo.

Results

We successfully fabricated a coaxially electrospun nanofiber MgONPs-PCL/PTH-PCL membrane with the majority of nanofibers (>65%) ranged from 0.40~0.60μm in diameter. MgONPs-PCL/PTH-PCL showed outstanding antibacterial potential against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) through the release of MgONPs. We also discovered that the incorporation of MgONPs significantly prolonged the release of PTH. Furthermore, both the in-vivo and in-vitro studies demonstrated that high dosage of PTH promoted pro-osteogenicity of the membrane to improve bone regeneration efficacy with the presence of MgONPs.

Conclusion

The new composite membrane is a promising approach to enhance bone regeneration in periodontitis or peri-implantitis patients with large-volume bone defects.

Sustained local ionic homeostatic imbalance caused by calcification modulates inflammation to trigger heterotopic ossification

Heterotopic ossification (HO) is a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues. Despite being a frequent complication of orthopedic and trauma surgery, brain and spinal injury, the etiology of HO is poorly understood. The aim of this study is to evaluate the hypothesis that a sustained local ionic homeostatic imbalance (SLIHI) created by mineral formation during tissue calcification modulates inflammation to trigger HO. This evaluation also considers the role SLIHI could play for the design of cell-free, drug-free osteoinductive bone graft substitutes. The evaluation contains five main sections. The first section defines relevant concepts in the context of HO and provides a summary of proposed causes of HO. The second section starts with a detailed analysis of the occurrence and involvement of calcification in HO. It is followed by an explanation of the causes of calcification and its consequences. This allows to speculate on the potential chemical modulators of inflammation and triggers of HO. The end of this second section is devoted to in vitro mineralization tests used to predict the ectopic potential of materials. The third section reviews the biological cascade of events occurring during pathological and material-induced HO, and attempts to propose a quantitative timeline of HO formation. The fourth section looks at potential ways to control HO formation, either acting on SLIHI or on inflammation. Chemical, physical, and drug-based approaches are considered. Finally, the evaluation finishes with a critical assessment of the definition of osteoinduction. STATEMENT OF SIGNIFICANCE: The ability to regenerate bone in a spatially controlled and reproducible manner is an essential prerequisite for the treatment of large bone defects. As such, understanding the mechanism leading to heterotopic ossification (HO), a condition triggered by an injury leading to the formation of mature lamellar bone in extraskeletal soft tissues, would be very useful. Unfortunately, the mechanism(s) behind HO is(are) poorly understood. The present study reviews the literature on HO and based on it, proposes that HO can be caused by a combination of inflammation and calcification. This mechanism helps to better understand current strategies to prevent and treat HO. It also shows new opportunities to improve the treatment of bone defects in orthopedic and dental procedures.

Bone regeneration of demineralized dentin matrix with platelet-rich fibrin and recombinant human bone morphogenetic protein-2 on the bone defects in rabbit calvaria

BACKGROUND

This study was to evaluate the bone formation ability of demineralized dentin matrix (DDM) combined with platelet-rich fibrinogen (PRF) and DDM combined with recombinant human bone morphogenetic protein-2 (rhBMP-2) to improve the osteoinductive ability of DDM.

METHODS

After four bone defects with a diameter of 8mm were created in the calvarium of each rabbit, DDM was grafted into the first defect (experimental groups 1), a combination of DDM and PRF was grafted into the second defect (experimental groups 2), and DDM with absorbed rhBMP-2 was grafted into the third defect (experimental groups 3). The fourth defect was used as the control group. Twelve healthy male rabbits (New Zealand, white rabbits) weighing around 3.0-4.0 kg were used. Among 12 rabbits, 3 rabbits were sacrificed immediately after surgery and at 2, 4, and 8 weeks after surgery, respectively. Histopathologic analysis and histomorphometric analysis were conducted to evaluate bone formation in each group.

RESULTS

The PRF/DDM group did not show a significantly higher degree of new bone formation in calvarial bone defects than the DDM group at 2, 4, and 8 weeks postoperatively in histopathological findings and histomorphometric results. On the other side, the rhBMP-2/DDM group showed higher degrees of new bone formation and calcification, and the lamellae of bone matrix, which are observed in mature bone tissue, were more distinctly visible in the rhBMP-2/DDM group. Moreover, the rhBMP-2/DDM group showed a significantly higher amount of new bone formation, compared to the DDM group at 4 and 8 weeks postoperatively (P<0.05) in histomorphometric results.

CONCLUSION

The DDM has great potential as a carrier for the maintenance and sustained release of rhBMP-2, which has been recently receiving wide attention as a type of signaling molecules to promote bone formation.

Bone regeneration using Wollastonite/β-TCP scaffolds implants in critical bone defect in rat calvaria

In order to provide favorable conditions for bone regeneration, a lot of biomaterials have been developed and evaluated, worldwide. Composite biomaterials have gained notoriety, as they combine desirable properties of each isolated material. Thus, in this research, bone repair capacity of three developed formulations of ceramic scaffolds were evaluated histomorphometrically, after implantation. Scaffolds were based on wollastonite (W) andβ-tricalcium phosphate (β-TCP) composites in three different ratios (wt.%). ThirtyWistarrats were randomly assigned to three experimental groups: W-20 (20 W/80β-TCP wt.%), W-60 (60 W/40β-TCP wt.%), and W-80 (80 W/20β-TCP wt.%), evaluated by optical microscopy at biological tests after 15 and 45 days of implantation. Throughout the study, the histological results evidenced that the scaffolds remained at the implantation site, were biocompatible and presented osteogenic potential. The percentage of neoformed mineralized tissue was more evident in the W-20 group (51%), at 45 days. The composite of the W-80 group showed more evident biodegradation than the biomaterials of the W-20 and W-60 groups. Thus, it is concluded that the scaffold containing 20 W/80β-TCP (wt.%) promoted more evident bone formation, but all composites evaluated in this study showed notorious bioactivity and promising characteristics for clinical application.

Evaluation of the regenerative potential of decellularized skeletal muscle seeded with mesenchymal stromal cells in critical-sized bone defect of rat models

Background

The morbidities and complications reported in the reconstruction of large bony defects have inspired progression in the field of bioengineering, with a recent breakthrough for the use of decellularized skeletal muscle grafts (DSMG).

Aim

To assess the osteogenic potentials of seeded DSMG in vitro and to investigate bone regeneration in critical size defect in vivo.

Materials and Methods

Assessment of cell viability and characterization was carried out on seeded DSMG for different intervals in vitro. For in vivo experiments, histological analysis was performed for rat cranial defects for the following groups: (A) non-treated DSMG and (B) seeded DSMG after a period of 8 weeks.

Results

The in vitro experiment demonstrated the lack of cytotoxicity and inert properties of seeded DSMG; these facilitated the osteogenic differentiation and significant gene expressions, particularly of COL1A1, RUNX2, and OPN (1.9174 ± 0.11673, 1.1806 ± 0.02383, and 1.1802 ± 0.00775, respectively). In the in vivo experiment, superior results were detected in the seeded DSMG group which showed highly vascularized and cellular dense connective tissue with deposited bone matrix and multiple scattered islets of newly formed bone.

Conclusion

Our results demonstrated the promising aspects of DSMG; however, there is a lack of studies to support further implications.

Heterotopic Ossification of the Vascular Pedicle after Maxillofacial Reconstructive Surgery Using Fibular Free Flap: Introducing New Classification and Retrospective Analysis

Heterotopic ossification (HO) is one of the described phenomena after maxillofacial reconstructive surgery using fibular free flap (FFF) at the reception-site. The aim of this study was to determine the radiological incidence and form of HO along the fibular vascular pedicle as well as the rate of clinical symptoms if present. CT-scans of 102 patients who underwent jaw reconstructive surgery by using FFF from January 2005 to December 2019 were evaluated concerning the presence of HO. Subsequently, the patient files were evaluated to identify the cases with clinical signs and complications related to the presence of HO. A radiological classification of four different HO types was developed. Out of 102 patients, 29 (28.43%) presented radiological findings of HO. Clinical symptoms were recorded in 10 cases (9.8%) (dysphagia (n = 5), trismus (n = 3), bony masses (n = 2)) and from these only five (4.9%) needed surgical removal of calcified structures. HO occurs significantly in younger patients (mean 52.3 year). In maxillary reconstructions, HO was radiologically visible six months earlier than after mandibular reconstruction. Furthermore, HO is observed after every third maxilla and every fourth mandible reconstruction. This study developed for the first time a classification of four distinct HO patterns. HO types 1 and 2 were mostly observed after mandible reconstruction and type 4 predominantly after maxilla reconstruction.

Effect of Honeycomb β-TCP Geometrical Structure on Bone Tissue Regeneration in Skull Defect

The effect of the geometric structure of artificial biomaterials on skull regeneration remains unclear. In a previous study, we succeeded in developing honeycomb β-tricalcium phosphate (β-TCP), which has through-and-through holes and is able to provide the optimum bone microenvironment for bone tissue regeneration. We demonstrated that β-TCP with 300-μm hole diameters induced vigorous bone formation. In the present study, we investigated how differences in hole directions of honeycomb β-TCP (horizontal or vertical holes) influence bone tissue regeneration in skull defects. Honeycomb β-TCP with vertical and horizontal holes was loaded with BMP-2 using Matrigel and Collagen gel as carriers, and transplanted into skull bone defect model rats. The results showed that in each four groups (Collagen alone group, Matrigel alone group, Collagen + BMP group and Matrigel + BMP-2), vigorous bone formation was observed on the vertical β-TCP compared with horizontal β-TCP. The osteogenic area was larger in the Matrigel groups (with and without BMP-2) than in the Collagen group (with and without BMP-2) in both vertical β-TCP and horizontal β-TCP. However, when BMP-2 was added, the bone formation area was not significantly different between the Collagen group and the Matrigel group in the vertical β-TCP. Histological finding showed that, in vertical honeycomb β-TCP, new bone formation extended to the upper part of the holes and was observed from the dura side to the periosteum side as added to the inner walls of the holes. Therefore, we can control efficient bone formation by creating a bone microenvironment provided by vertical honeycomb β-TCP. Vertical honeycomb β-TCP has the potential to be an excellent biomaterial for bone tissue regeneration in skull defects and is expected to have clinical applications.

Evaluation of New Octacalcium Phosphate-Coated Xenograft in Rats Calvarial Defect Model on Bone Regeneration

Bone graft material is essential for satisfactory and sufficient bone growth which leads to a successful implant procedure. It is classified into autogenous bone, allobone, xenobone and alloplastic materials. Among them, it has been reported that heterogeneous bone graft material has a porous microstructure that increases blood vessels and bone formation, and shows faster bone formation than other types of bone graft materials. We observed new bone tissue formation and bone remodeling using Ti-oss^® (Chiyewon Co., Ltd., Guri, Korea), a heterologous bone graft material. Using a Sprague–Dawley rat calvarial defect model to evaluate the bone healing effect of biomaterials, the efficacy of the newly developed xenograft Ti-oss^® and Bio-Oss^® (Geistilch Pharma AG, Wolhusen, Switzerland). The experimental animals were sacrificed at 8 and 12 weeks after surgery for each group and the experimental site was extracted. The average new bone area for the Ti-oss^® experimental group at 8 weeks was 17.6%. The remaining graft material was 22.7% for the experimental group. The average new bone area for the Ti-oss^® group was 24.3% at 12 weeks. The remaining graft material was 22.8% for the experimental group. It can be evaluated that the new bone-forming ability of Ti-oss^® with octacalcium phosphate (OCP) has the bone-forming ability corresponding to the conventional products.

In vivo evaluation of bilayer ORC/PCL composites in a rabbit model for using as a dural substitute

OBJECTIVE

After a neurosurgical procedure, dural closure is commonly needed to prevent cerebrospinal fluids (CSF) leakage and to reduce the risk of complications, including infections and chronic inflammatory reactions. Although several dural substitutes have been developed, their manufacturing processes are complicated and costly and that many of them have been implicated in causing postoperative complications. This study aimed to assess the effectiveness and safety of new bilayer ORC/PCL composites in a rabbit model.

METHODS

Two formulations of bilayer oxidized regenerated cellulose (ORC)/poly ε-caprolactone (PCL) knitted fabric-reinforced composites and an autologous graft (pericranium) were employed for dural closure in forty-five male rabbits. Systemic reaction and the local reaction of the samples were assessed and compared at one-, three- and six-months post-implantation by blood chemistry and gross, and microscopic assessment using hematoxylin-eosin and Masson's trichrome stains.

RESULTS

No signs of CSF leakage or systemic infection were seen for all samples. All samples demonstrated minimal adhesion to adjacent tissues. The degree of host fibrous connective tissue ingrowth into both composites was comparable to that of the autologous group, but bone formation and osteoclast activities were significantly greater. Both composites progressively degraded over times and the residual thickness of the nonporous layer was 50% of the initial thickness at six months post-implantation.

DISCUSSION

Bilayer ORC/PCL composites were successfully employed for dural closure in the rabbit model. They were biocompatible and could support dural regeneration comparable to that of the autologous group, but induced greater osteogenesis.

Calvaria critical-size defects in rats using piezoelectric equipment: a comparison with the classic trephine

Calvarial critical-size defects in rats are used to study regeneration of both craniofacial bone and long-bones. For decades, the trephine technique has been used with no notable refinements in the procedure. The use of piezoelectric surgical equipment has increased in human clinical oral and maxillofacial surgery, neurosurgery, traumatology, and orthopedics, because the devices are easy to handle, and can cut bone without damaging sensitive soft tissues such as blood vessels, nerves, and membranes. This study evaluated and compared the surgical technique and bone regeneration process between a traditional hand-drill trephine and piezoelectric equipment in a critical-size calvaria defect in a rat model. Thirty SD male rats were randomly divided into two groups and had either a 7.9mm diameter circular defect created with trephine or a 7.0mm square defect using the piezoelectric device, both creating 49 mm2 defect areas. MicroCT and histology were performed at 45 and 75d after surgery. While trephine surgeries were performed faster than piezoelectric (25.5 minutes vs 38.5 minutes), the rate of complications was much higher, with 36% of trephine rats taking 20 minutes to achieve hemostasis. Although the extent of new bone formation was similar between the two surgical groups, the piezoelectric technique resulted in 50% less variability. No additional new bone formation was observed from 45 to 75d in both techniques. Piezoelectric technique represents a refined and more reproducible technique for calvarial defect generation in comparison to classic trephine methods.

Treatment of Critical-Sized Calvarial Defects in Rats with Preimplanted Transplants

The local environment and the defect features have made the skull one of the most difficult regions to repair. Finding alternative strategies to repair large cranial defects, thereby avoiding the current limitations of autograft or polymeric and ceramic prostheses constitute an unmet need. In this study, the regeneration of an 8 mm critical-sized calvarial defect treated by autograft or by a monetite scaffold directly placed in the defect or preimplanted (either cranial bone transplant or subcutaneous pocket) and then transplanted within the bone defect is compared. The data reveal that transplantation of preimplanted monetite transplant scaffolds greatly improves the skull vault closure compared to subcutaneously preimplanted or directly placed materials. Autografts, while clearly filling the defect volume with bone appear effective since bone volume inside the defect volume is obviously high, but are not well fused to the skull. The preimplantation site has a large influence on the regeneration of the defect. Transplantation of induced bone inside materials has the potential to reduce the need for autograft harvest without damaging the skeleton. This first demonstration indicates that cranial repair may be possible without recourse to bioactives or cultured cell therapies.

Vertical ridge augmentation using a porous composite of uncalcined hydroxyapatite and poly-DL-lactide enriched with types 1 and 3 collagen

BACKGROUND

Previous studies have shown that porous composite blocks containing uncalcined hydroxyapatite (u-HA; 70 wt%) with a scaffold of poly-DL-lactide (PDLLA, 30 wt%) are biodegradable, encourage appropriate bone formation, and are suitable for use as a bone substitute in vertical ridge augmentation. The present study aimed to accelerate osteogenesis in vertical ridge formation by adding types 1 and 3 collagen to the u-HA/PDLLA blocks and assessing the effect.

MATERIAL AND METHODS

The bone substitute in the present study comprised porous composite blocks of u-HA (70 wt%) with a PDLLA (27-29 wt%) scaffold and enriched with types 1 and 3 collagen (1.7 ~ 3.4 wt%). The control blocks were composed of u-HA (70 wt%) and PDLLA (30 wt%). The materials were formed into 8-mm diameter, 2-mm high discs and implanted onto the cranial bones of six rabbits. The animals were sacrificed 4 weeks after implantation, and histological and histomorphometrical analyses were performed to quantitatively evaluate newly formed bone.

RESULTS

New bone formation occurred with both block types, showing direct contact with the original bone. Mean ± standard deviation bone formation was significantly greater in the experimental blocks (25.6% ± 4.8%) than in the control blocks (17.0% ± 4.7%).

CONCLUSIONS

Histological and histomorphometrical observations indicated that new bone was formed with both block types. The u-HA/PDLLA block with types 1 and 3 collagen is a more promising candidate for vertical ridge augmentation than the u-HA/PDLLA alone block.

Bone Regeneration Effect of Hyperbaric Oxygen Therapy Duration on Calvarial Defects in Irradiated Rats

Objective

In this study, we evaluated changes in bone remodeling in an irradiated rat calvarial defect model according to duration of hyperbaric oxygen therapy.

Materials and Methods

The 28 rats were divided into four groups. Radiation of 12 Gy was applied to the skull, and 5-mm critical size defects were formed on both sides of the skull. Bone grafts were applied to one side of formed defects. From the day after surgery, HBO was applied for 0, 1, and 3 weeks. At 6 weeks after bone graft, experimental sites were removed and analyzed for radiography, histology, and histomorphometry.

Results

Micro-CT analysis showed a significant increase in new bone volume in the HBO-3 group, with or without bone graft. When bone grafting was performed, BV, BS, and BS/TV all significantly increased. Histomorphometric analysis showed significant increases in %NBA and %BVN in the HBO-1 and HBO-3 groups, regardless of bone graft.

Conclusion

Hyperbaric oxygen therapy was effective for bone regeneration with only 1 week of treatment.

Osteogenic Enhancement Between Icariin and Bone Morphogenetic Protein 2: A Potential Osteogenic Compound for Bone Tissue Engineering

Icariin, a typical flavonol glycoside, is the main active component of Herba Epimedii, which was used to cure bone-related diseases in China for centuries. It has been reported that Icariin can be delivered locally by biomaterials and it has an osteogenic potential for bone tissue engineering. Biomimetic calcium phosphate (BioCaP) bone substitute is a novel drug delivery carrier system. Our study aimed to evaluate the osteogenic potential when Icariin was internally incorporated into the BioCaP granules. The BioCaP combined with Icariin and bone morphogenetic protein 2 (BMP-2) was investigated in vitro using an MC3T3-E1 cell line. We also investigated its efficacy to repair 8 mm diameter critical size bone defects in the skull of SD male rats. BioCaP was fabricated according to a well-established biomimetic mineralization process. In vitro, the effects of BioCaP alone or BioCaP with Icariin and/or BMP-2 on cell proliferation and osteogenic differentiation of MC3T3-E1 cells were systematically evaluated. In vivo, BioCaP alone or BioCaP with Icariin and/or BMP-2 were used to study the bone formation in a critical-sized bone defect created in a rat skull. Samples were retrieved for Micro-CT and histological analysis 12 weeks after surgery. The results indicated that BioCaP with or without the incorporation of Icariin had a positive effect on the osteogenic differentiation of MC3T3-E1. BioCaP with Icariin had better osteogenic efficiency, but had no influence on cell proliferation. BioCap + Icariin + BMP-2 showed better osteogenic potential compared with BioCaP with BMP-2 alone. The protein and mRNA expression of alkaline phosphatase and osteocalcin and mineralization were higher as well. In vivo, BioCaP incorporate internally with both Icariin and BMP-2 induced significantly more newly formed bone than the control group and BioCaP with either Icariin or BMP-2 did. Micro-CT analysis revealed that no significant differences were found between the bone mineral density induced by BioCaP with icariin and that induced by BioCaP with BMP-2. Therefore, co-administration of Icariin and BMP-2 was helpful for bone tissue engineering.

Efficacy of Octacalcium Phosphate and Octacalcium Phosphate/Gelatin Composite on the Repair of Critical-Sized Calvarial Defects in Rats

OBJECTIVES

The healing of bone defects in the craniofacial region is an important clinical issue. We aimed to compare the effects of octacalcium phosphate (OCP) and the combination of OCP/gelatin (OCP/Gel) on calvarial bone regeneration in rats.

MATERIALS AND METHODS

In this study, 72 male Sprague Dawley rats were randomly assigned to the OCP (n=24), OCP/Gel (n=24), and control groups (n=24). Lesions with a diameter of 9 mm were created in the parietal bone and were filled with 9-mg OCP and OCP/Gel disks. In the control group, no substance was implanted in the defect. Sampling was performed on days 10, 14, 21, and 28 after the implantation. After tissue processing, 5-μm sections were prepared and stained by hematoxylin and eosin (H&E) stain. The sections were studied, and the volume fraction of the newly formed bone was assessed by Kruskal-Wallis test at a significance level of 0.05.

RESULTS

In the experimental groups, new bone formation was detected at the margins of the defects 10 days after the implantation. With the progression of the healing process, the newly formed bone covered greater areas of the defects and developed a more mature structure. In the control group, the defects were primarily filled with a dense connective tissue with small islands of new bone. The results of histomorphometric assessments showed that the volume of the newly formed bone in the experimental groups had a significant statistical difference with that in the control group (P<0.001).

CONCLUSIONS

The OCP/Gel composite can be useful in the healing process of calvarial bone defects.

Comparison of Resorbable Mesh (Poly L-Lactide/Glycolic Acid) and Porous Polyethylene in Orbital Floor Fractures in an Experimental Model

BACKGROUND

Resorbable mesh and porous polyethylene are frequently used alloplastic materials for the treatment of the orbital blowout fractures. The literature lacks reports comparing their long-term effects on experimental models.

OBJECTIVE

Our aim was to radiologically and histologically evaluate the effectiveness and safety of porous polyethylene and resorbable mesh in a rabbit orbital blowout fracture model.

METHODS

Twelve New Zealand white rabbits (24 orbits) were randomized to 4 groups. In group 1, only orbital floor dissection was done. In group 2, following orbital floor dissection, a 10-mm defect was created without any extra procedure. In group 3, following a 10-mm defect creation, a 12-mm-round cut porous polyethylene was placed on the defect. In group 4, following a 10-mm defect creation, a 12-mm-round cut resorbable mesh was placed on the defect. Computed tomographic analysis was performed during follow-up period. Orbital floors were evaluated histologically at month 6.

RESULTS

No clinical complications were observed during follow-up period. In radiological evaluation, there was no statistically significant difference between groups regarding bone formation. In histological evaluation, the connective tissue was denser, and organized and better bone formation was observed in group 3 and 4 when compared with other groups.

CONCLUSION

Although no significant radiological changes were present, porous polyethylene and resorbable mesh performed better histologically. They were effective and well tolerated for reconstruction of the isolated orbital floor defects.

Effects of Rat Bone Marrow-Derived Mesenchymal Stem Cells and Demineralized Bone Matrix on Cranial Bone Healing

BACKGROUND

Studies in tissue engineering about mesenchymal stem cells (MSCs) provide promising results for bone regeneration. The aim of this study was to evaluate the effects of rat bone marrow-derived MSCs (rMSCs) alone and when combined with demineralized bone matrix (DBM) on critical-sized cranial defects of rats.

METHODS

Ten rats were used to obtain allogeneic rMSCs. Forty rats were separated equally into 4 groups. A full-thickness circular bone defect was created in the frontal bone of the rats. Group 1 was an operative control group. In group 2 DBM, in group 3 rMSCs, and in group 4 DBM combined with rMSCs were applied into the defects. Bone regeneration was evaluated by computed tomographic analysis and immunohistochemistry.

RESULTS

In radiological evaluation, the percentage of area healed in group 3 at the 12th week was statistically significantly greater than in group 1. In group 3 and group 4, distributed healing patterns were observed more than in group 2 and in group 1. Immunohistochemical evaluation revealed that group 4 had the best osteoinductive potential. Osteoinductive potential of group 3 was similar to group 2 and was better than group 1.

CONCLUSIONS

Allogeneic rMSC applications have created a statistically significant radiologic reduction of the bone defect areas at the end of the 12 weeks. The MSC applications have also increased the bone density and changed the healing patterns. Combined use of the DBM and rMSCs has created more osteoinductive responses. This combination can provide better results in craniofacial bone reconstruction.

The traumatic bone: trauma-induced heterotopic ossification

Heterotopic ossification (HO) is a common occurrence after multiple forms of extensive trauma. These include arthroplasties, traumatic brain and spinal cord injuries, extensive burns in the civilian setting, and combat-related extremity injuries in the battlefield. Irrespective of the form of trauma, heterotopic bone is typically endochondral in structure and is laid down via a cartilaginous matrix. Once formed, the heterotopic bone typically needs to be excised surgically, which may result in wound healing complications, in addition to a risk of recurrence. Refinements of existing diagnostic modalities, like micro- and nano-CT are being adapted toward early intervention. Trauma-induced HO is a consequence of aberrant wound healing, systemic and local immune system activation, infections, extensive vascularization, and innervation. This intricate molecular crosstalk culminates in activation of stem cells that initiate heterotopic endochondral ossification. Development of animal models recapitulating the unique traumatic injuries has greatly facilitated the mechanistic understanding of trauma-induced HO. These same models also serve as powerful tools to test the efficacy of small molecules which specifically target the molecular pathways underlying ectopic ossification. This review summarizes the recent advances in the molecular understanding, diagnostic and treatment modalities in the field of trauma-induced HO.

The Effects of Nigella Sativa Seed Extract on Bone Healing in an Experimental Model

The purpose of this study was to histologically evaluate the effects on bone healing of nigella sativa seed extract applied on calvarial defects in an ovariectomized rat model. The study included 32 female rats weighing 280 to 310 g with an average age of 3 months. A defect was created with a trephine burr on each rat calvarium. The rats were divided into 2 groups (control and study) of 8 animals each. All the defects were grafted with a gelatin sponge mixed with normal saline. In the study group, nigella sativa seed extract was applied systemically using an oro-gastric tube. Half of the animals in each group were sacrificed after 2 weeks, and the others after 4 weeks. In the control groups, the defects were not completely filled with regenerated bone. Osteoblast cells were observed more in the study groups. A higher rate of osteoclasts was determined in the control groups. In addition, the nigella sativa group had a statistically greater amount of bone formation than the others group at both 2 weeks and 4 weeks (P <0.05). The systemic application of nigella sativa seed extract demonstrated incredibly positive effects on enhanced bone healing in this experimental osteoporotic model.

Effect of Resorbable Collagen Plug on Bone Regeneration in Rat Critical-Size Defect Model

OBJECTIVE

The purpose of this investigation was to examine the effect of resorbable collagen plug (RCP) on bone regeneration in rat calvarial critical-size defects.

METHODS

About 5-mm-diameter calvarial defects were created in forty 12-week-old male Sprague-Dawley rats and implanted with or without RCP. Animals were killed at 1, 2, 4, and 8 weeks postoperatively. After being killed, specimens were collected and subjected to micro-computed tomography (μCT) and histological analysis.

RESULTS

The μCT showed a significant increase of newly formed bone volume/tissue volume in RCP-implanted defect compared with controls at all designated time points. After 8 weeks, the defects implanted with RCP displayed almost complete closure. Hematoxylin and eosin staining of the decalcified sections confirmed these observations and evidenced active bone regeneration in the RCP group. In addition, Masson's trichrome staining demonstrated that RCP implantation accelerated the process of collagen maturation.

CONCLUSIONS

The RCP enhances bone regeneration in rat critical-size cranial defects, which suggest it might be a desired material for bone defect repair.

A composite critical-size rabbit mandibular defect for evaluation of craniofacial tissue regeneration

Translational biomaterials targeted toward the regeneration of large bone defects in the mandible require a preclinical model that accurately recapitulates the regenerative challenges present in humans. Computational modeling and in vitro assays do not fully replicate the in vivo environment. Consequently, in vivo models can have specific applications such as those of the mandibular angle defect, which is used to investigate bone regeneration in a nonload-bearing area, and the inferior border mandibular defect, which is a model for composite bone and nerve regeneration, with both models avoiding involvement of soft tissue or teeth. In this protocol, we describe a reproducible load-bearing critical-size composite tissue defect comprising loss of soft tissue, bone and tooth in the mandible of a rabbit. We have previously used this procedure to investigate bone regeneration, vascularization and infection prevention in response to new biomaterial formulations for craniofacial tissue engineering applications. This surgical approach can be adapted to investigate models such as that of regeneration in the context of osteoporosis or irradiation. The procedure can be performed by researchers with basic surgical skills such as dissection and suturing. The procedure takes 1.5-2 h, with ∼2 h of immediate postoperative care, and animals should be monitored daily for the remainder of the study. For bone tissue engineering applications, tissue collection typically occurs 12 weeks after surgery. In this protocol, we will present the necessary steps to ensure reproducibility; tips to minimize complications during and after surgery; and analytical techniques for assessing soft tissue, bone and vessel regeneration by gross evaluation, microcomputed tomography (microCT) and histology.

Evaluation of bone regenerative capacity in rats claverial bone defect using platelet rich fibrin with and without beta tri calcium phosphate bone graft material

Aim

To compare bone regeneration in noncritical rat calvarial bone defects filled with platelet-rich fibrin (PRF), alone or combined with beta-tricalcium phosphate (β-TCP), using micro-computed tomographic (MCT) evaluation.

Animals and methods

Two calvarial bone defects were created in each of 45 male Sprague–Dawley rats (age: 20–22 weeks, weight: 350–450 g), using a dental trephine with an external diameter of 3 mm. The 90 defects were randomly allocated among three groups, each containing 30 unilateral defects in a total of 30 rats. Defects in the control group were allowed to heal spontaneously. Defects in the PRF group received PRF alone. Defects in the PRF/β-TCP group received PRF mixed with β-TCP in a 50⧹50 percentage. Nine animals (three per group) were killed after 1, 2, 3, 4, and 6 postoperative weeks, and 18 calvarial defects from each period were analyzed for new bone formation and bone mineral density using MCT. Results were compared by a one-way Analysis of Variance with the POST HOC Least Significant Difference test.

Results

The volume and mineral density of bone formed in the control group were significantly different from those of the other two groups. Greater bone regeneration was observed in defects receiving PRF with β-TCP compared to defects receiving PRF alone in the first 2 weeks (P < 0.001). However, differences in the volume and density of newly formed bone between the PRF and PRF/β-TCP groups were not significant at 3, 4, and 6 postoperative weeks (P > 0.005).

Conclusion

The addition of β-TCP to PRF significantly improved bone regeneration in the first 2 weeks after surgery. Although the differences between results with and without the addition of β-TCP to PRF were statistically insignificant from weeks 3 to 6, it was nevertheless apparent that the group receiving the combination showed better results. We suggest a synergistic mechanism for this effect.

Tissue segregation restores the induction of bone formation by the mammalian transforming growth factor-β(3) in calvarial defects of the non-human primate Papio ursinus

A diffusion molecular hypothesis from the dura and/or the leptomeninges below that would control the induction of calvarial membranous bone formation by the recombinant human transforming growth factor-β3 (hTGF-β3) was investigated. Coral-derived calcium carbonate-based macroporous constructs (25 mm diameter; 3.5/4 mm thickness) with limited hydrothermal conversion to hydroxyapatite (7% HA/CC) were inserted into forty calvarial defects created in 10 adult Chacma baboons Papio ursinus. In 20 defects, an impermeable nylon foil membrane (SupraFOIL(®)) was inserted between the cut endocranial bone and the underlying dura mater. Twenty of the macroporous constructs were preloaded with hTGF-β3 (125 μg in 1000 μl 20 mM sodium succinate, 4% mannitol pH4.0), 10 of which were implanted into defects segregated by the SupraFOIL(®) membrane, and 10 into non-segregated defects. Tissues were harvested on day 90, processed for decalcified and undecalcified histology and quantitative real-time polymerase chain reaction (qRT-PCR). Segregated untreated macroporous specimens showed a reduction of bone formation across the macroporous spaces compared to non-segregated constructs. qRT-PCR of segregated untreated specimens showed down regulation of osteogenic protein-1 (OP-1), osteocalcin (OC), bone morphogenetic protein-2 (BMP-2), RUNX-2 and inhibitor of DNA binding-2 and -3 (ID2,ID3) and up regulation of TGF-β3, a molecular signalling pathway inhibiting the induction of membranous bone formation. Non-segregated hTGF-β3/treated constructs also showed non-osteogenic expression profiles when compared to non-segregated untreated specimens. Segregated hTGF-β3/treated 7% HA/CC constructs showed significantly greater induction of bone formation across the macroporous spaces and, compared to non-segregated hTGF-β3/treated constructs, showed up regulation of OP-1, OC, BMP-2, RUNX-2, ID2 and ID3. Similar up-regulated expression profiles were seen for untreated non-segregated constructs. TGF-β signalling via ID genes creates permissive or refractory micro-environments that regulate the induction of calvarial bone formation which is controlled by the exogenous hTGF-β3 upon segregation of the calvarial defects. The dura is the common regulator of the induction of calvarial bone formation modulated by the presence or absence of the SupraFOIL(®) membrane with or without hTGF-β3.

Sequential delivery of BMP-2 and BMP-7 for bone regeneration using a heparinized collagen membrane

To investigate the effect of the sequential delivery of bone morphogenetic proteins BMP-2 and BMP-7 on bone regeneration in rat calvarial defects (40 Sprague-Dawley rats, 8mm defect size), all animals were treated with a hydroxyapatite (HA)/tricalcium phosphate (TCP) bone graft covered with a collagen membrane. The experimental groups were as follows: (1) control group: unmodified collagen (no treatment); (2) BMP-2 group: 5 μg of BMP-2; (3) hep-BMP-7 group: 5 μg BMP-7 chemically bound to heparinized collagen; and (4) BMP-2/hep-BMP-7 group: 2.5 μg BMP-7 bound to heparinized collagen and subsequently treated with 2.5 μg BMP-2. Defect healing was examined at 2 and 8 weeks after surgery. The BMP-2 group showed the largest new bone area at week 2 (29.3 ± 7.3%; P = 0.009); new bone areas in the hep-BMP-7 and BMP-2/hep-BMP-7 groups were similar (11.8 ± 3.4% and 12.9 ± 5.71%, respectively; P = 0.917). After 8 weeks, the BMP-2/hep-BMP-7 group showed the largest new bone area (43.3 ± 6.2%), followed by the BMP-2 and hep-BMP-7 groups (P = 0.013). Accordingly, in comparison with single deliveries of BMP-2 and BMP-7, sequential delivery of BMP-2 and BMP-7 using a heparinized collagen membrane significantly induced new bone formation with a smaller quantity of BMP-2 in rat calvarial defects.

Effects of caffeic acid phenethyl ester on wound healing in calvarial defects

OBJECTIVE

The aim of this study is to analyze histologically the effect of CAPE on bone healing of Critical Size Defect (CSD) in rat calvaria.

STUDY DESIGN

Thirty-two 3-month-old male rats were used. The animals were randomly divided into four groups. Group A received isotonic saline solution, Group B received CAPE (50 mmol/kg) locally, Group C received CAPE (100 mmol/kg) locally and Group D received CAPE (10 mmol/kg/day i.p. for 28 days) systematically. A 5-mm diameter calvarial defect was created in the right side of the parietal bone without damaging the underlying dura mater. Twenty-eight days after the surgery, all the animals were sacrificed. The original defect area was removed from the animal's calvarium bone en bloc. Beginning at the center of the surgical defect, serial sections of 6 µm thick were cut longitudinally. The sections were stained with hematoxylin and eosin for analysis under a light microscope. The sections were analyzed for the presence of inflammatory infiltrate, connective tissue formation and new bone formation. Computer-assisted histomorphometic measurements were carried out with an automated image analysis system.

RESULTS

The total new bone areas were significantly greater in group D than in all groups and group C was statistically insignificant from the other groups (p < 0.05). Group B had a greater, but not statistically significant (p > 0.05), amount of total regenerated bone area than the control group.

CONCLUSION

The results indicate that 100 mmol/kg topical and 10 mmol/kg/day systemic application of CAPE increases bone healing, especially with systemic application.

An in vivo murine model for screening cranial bone regenerative materials: testing of a novel synthetic collagen gel

Rapid and efficient animal models are needed for evaluating the effectiveness of many new candidate bone regenerative materials. We developed an in vivo model screening for calvarial bone regeneration in lipopolysaccharide (LPS)-treated mice, in which materials were overlaid on the periosteum of the calvaria in a 20 min surgery and results were detectable in 1 week. Intraperitoneal LPS injection reduced spontaneous bone formation, and local application of basic fibroblast growth factor (bFGF) increased the bone-forming activities of osteoblasts. A novel synthetic collagen gel, alkali-treated collagen (AlCol) cross-linked with trisuccinimidyl citrate (TSC), acted as a reservoir for basic substances such as bFGF. The AlCol-TSC gel in conjunction with bFGF activated osteoblast activity without the delay in osteoid maturation caused by bFGF administration alone. The AlCol-TSC gel may slow the release of bFGF to improve the imbalance between osteoid formation and bone mineralization. These findings suggest that our model is suitable for screening bone regenerative materials and that the AlCOl-TSC gel functions as a candidate reservoir for the slow release of bFGF.

Missing Concepts in De Novo Pulp Regeneration

Regenerative endodontics has gained much attention in the past decade because it offers an alternative approach in treating endodontically involved teeth. Instead of filling the canal space with artificial materials, it attempts to fill the canal with vital tissues. The objective of regeneration is to regain the tissue and restore its function to the original state. In terms of pulp regeneration, a clinical protocol that intends to reestablish pulp/dentin tissues in the canal space has been developed--termed revitalization or revascularization. Histologic studies from animal and human teeth receiving revitalization have shown that pulp regeneration is difficult to achieve. In tissue engineering, there are 2 approaches to regeneration tissues: cell based and cell free. The former involves transplanting exogenous cells into the host, and the latter does not. Revitalization belongs to the latter approach. A number of crucial concepts have not been well discussed, noted, or understood in the field of regenerative endodontics in terms of pulp/dentin regeneration: (1) critical size defect of dentin and pulp, (2) cell lineage commitment to odontoblasts, (3) regeneration vs. repair, and (4) hurdles of cell-based pulp regeneration for clinical applications. This review article elaborates on these missing concepts and analyzes them at their cellular and molecular levels, which will in part explain why the non-cell-based revitalization procedure is difficult to establish pulp/dentin regeneration. Although the cell-based approach has been proven to regenerate pulp/dentin, such an approach will face barriers--with the key hurdle being the shortage of the current good manufacturing practice facilities, discussed herein.

Stimulation of bone regeneration following the controlled release of water-insoluble oxysterol from biodegradable hydrogel

Recently bone graft substitutes using bone morphogenetic proteins (BMPs) have been heralded as potential alternatives to traditional bone reconstruction procedures. BMP-based products, however, are associated with significant and potentially life-threatening side effects when used in the head and neck region and furthermore, are exorbitantly priced. Oxysterols, products of cholesterol oxidation, represent a class of molecules that are favorable alternatives or adjuncts to BMP therapy due to their low side effect profile and cost. In order to establish the optimal clinical utility of oxysterol, an optimal scaffold must be developed, one that allows the release of oxysterol in a sustained and efficient manner. In this study, we prepare a clinically applicable bone graft substitute engineered for the optimal release of oxysterol. We first solubilized oxysterol in water by making use of polymeric micelles using l-lactic acid oligomer (LAo) grafted gelatin. Then, the water-solubilized oxysterol was incorporated into a biodegradable hydrogel that was enzymatically degraded intracorporeally. In this manner, oxysterol could be released from the hydrogel in a degradation-driven manner. The water-solubilized oxysterol incorporated biodegradable hydrogel was implanted into rat calvarial defects and induced successful bone regeneration. The innovative significance of this study lies in the development of a bone graft substitute that couples the osteogenic activity of oxysterol with a scaffold designed for optimized oxysterol release kinetics, all of which lead to better repair of bone defects.

Injectable gel graft for bone defect repair

Aim: To examine the performance of an injectable gel graft made of transglutaminase (Tg)-crosslinked gelatin gel with BMP-2 (BMP-2–Tg–Gel) for bone defect repair in animal models. Materials & methods: BMP-2 mixed with gelatin gel was crosslinked using Tg. The release of tethered BMP-2 through autocrine and paracrine pathways was demonstrated by using C2C12 and NIH 3T3 cells, respectively. BMP-2–Tg–Gel was injected into the induced cranial defect site. After 14 days, the sample was removed for x-ray imaging and histological evaluation. Results: Our in vivo results demonstrated that the injectable Tg–Gel with its osteoconductivity and controllable BMP-2 activity induced bone formation in our rat models when tethered with BMP-2. Conclusion: Tg–Gel as an injectable functional bone graft may enable the use of minimally invasive surgical procedures to treat irregular-shaped bone defects. Furthermore, this novel approach is capable of incorporating and controlling the release of therapeutic agents that may advance the science of tissue regeneration.

Poly(vinylidene-trifluoroethylene)/barium titanate composite for in vivo support of bone formation

In this study, we evaluated the effect of poly(vinylidene fluoride-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT) membrane on in vivo bone formation. Rat calvarial bone defects were implanted with P(VDF-TrFE)/BT and polytetrafluoroethylene (PTFE) membranes, and at 4 and 8 weeks, histomorphometric and gene expression analyses were performed. A higher amount of bone formation was noticed on P(VDF-TrFE)/BT compared with PTFE. The gene expression of RUNX2, bone sialoprotein, osteocalcin, receptor activator of nuclear factor-kappa B ligand, and osteoprotegerin indicates that P(VDF-TrFE)/BT favored the osteoblast differentiation compared with PTFE. These results evidenced the benefits of using P(VDF-TrFE)/BT to promote new bone formation, which may represent a promising alternative to be employed in guided bone regeneration.