Combination of a Synthetic Bioceramic Associated with a Polydioxanone-Based Membrane as an Alternative to Autogenous Bone Grafting

The purpose of this study was to evaluate the repair process in rat calvaria filled with synthetic biphasic bioceramics (Plenum® Osshp-70:30, HA:βTCP) or autogenous bone, covered with a polydioxanone membrane (PDO). A total of 48 rats were divided into two groups (n = 24): particulate autogenous bone + Plenum® Guide (AUTOPT+PG) or Plenum® Osshp + Plenum® Guide (PO+PG). A defect was created in the calvaria, filled with the grafts, and covered with a PDO membrane, and euthanasia took place at 7, 30, and 60 days. Micro-CT showed no statistical difference between the groups, but there was an increase in bone volume (56.26%), the number of trabeculae (2.76 mm), and intersection surface (26.76 mm2) and a decrease in total porosity (43.79%) in the PO+PG group, as well as higher values for the daily mineral apposition rate (7.16 µm/day). Histometric analysis presented material replacement and increased bone formation at 30 days compared to 7 days in both groups. Immunostaining showed a similar pattern between the groups, with an increase in proteins related to bone remodeling and formation. In conclusion, Plenum® Osshp + Plenum® Guide showed similar and sometimes superior results when compared to autogenous bone, making it a competent option as a bone substitute.

Sudoku of porous, injectable calcium phosphate cements – Path to osteoinductivity

With the increase of global population, people's life expectancy is growing as well. Humans tend to live more active lifestyles and, therefore, trauma generated large defects become more common. Instances of tumour resection or pathological conditions and complex orthopaedic issues occur more frequently increasing necessity for bone substitutes. Composition of calcium phosphate cements (CPCs) is comparable to the chemical structure of bone minerals. Their ability to self-set and resorb in vivo secures a variety of potential applications in bone regeneration. Despite the years-long research and several products already reaching the market, finding the right properties for calcium phosphate cement to be osteoinductive and both injectable and suitable for clinical use is still a sudoku. This article is focused on injectable, porous CPCs, reviewing the latest developments on the path toward finding osteoinductive material, which is suitable for injection.

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Phase separation is an essential factor to be improved to obtain injectable material; several methods have been proposed.

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Osteoinductive bone substitutes – possible solution for bad mechanical performance of CPCs.

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Osteoinductivity of CPC could be attained even without the addition of different supplements.

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Less complex composition of CPC – potentially reduced price of the final product and wider availability on the market.

Loading of erythropoietin on biphasic calcium phosphate bioceramics promotes osteogenesis and angiogenesis by regulating EphB4/EphrinB2 molecules

Improving osteogenesis and angiogenesis using different cells and drugs is critical in the field of bone tissue engineering. Recent research has found that erythropoietin (EPO) plays an important role in both osteogenesis and angiogenesis. In this study, we grafted polydopamine and EPO onto the surface of biphasic calcium phosphate. The characterization and release property of the modified bioceramics were assessed. Cell proliferation, expression of osteoblastic and endothelial markers, and EphB4/EphrinB2 molecules were investigated while employing co-cultures of two different cells [rat vein endothelial cells (VECs) and rat bone marrow mesenchymal stromal cells (BMSCs)]. The modified bioceramics were finally implanted into the SD rats' femurs and followed by investigating the bone defect repair efficacy and the expression of EphB4/EphrinB2 molecules in vivo. The results indicated that the modified bioceramics could control the release of EPO continuously. The osteogenesis and angiogenesis were improved along with the increased expression of EphB4/EphrinB2 molecules. The expression of EphB4/EphrinB2 molecules was also significantly increased in vivo and the bone defect was repaired effectively. Overall, our findings demonstrated that EPO loading on biphasic calcium phosphate bioceramics could promote both osteogenesis and angiogenesis. The results suggest that EphB4/EphrinB2 may be crucial in the process. Graphical abstract.

Effectiveness of treating segmental bone defects with a synergistic co-delivery approach with platelet-rich fibrin and tricalcium phosphate

Several studies have applied tricalcium phosphate (TCP) or autografts in bone tissue engineering to enhance the clinical regeneration of bone. Unfortunately, there are several drawbacks related to the use of autografts, including a risk of infection, blood loss, limited quantities, and donor-site morbidities. Platelet-rich fibrin (PRF) is a natural extracellular matrix (ECM) biomaterial that possesses bioactive factors, which can generally be used in regenerative medicine. The goal of the present investigation was to develop osteoconductive TCP incorporated with bioactive PRF for bio-synergistic bone regeneration and examine the potential biological mechanisms and applications. Our in vitro results showed that PRF plus TCP had excellent biosafety and was favorable for initiating osteoblast cell attachment, slow release of bioactive factors, cell proliferation, cell migration, and ECM formation that potentially impacted bone repair. In a rabbit femoral segmental bone defect model, regeneration of bone was considerably augmented in defects locally implanted by PRF plus TCP according to radiographic and histologic examinations. Notably, the outcomes of this investigation suggest that the combination of PRF and TCP possesses novel synergistic and bio-inspired functions that facilitate bone regeneration.

Preliminary Animal Study on Bone Formation Ability of Commercialized Particle-Type Bone Graft with Increased Operability by Hydrogel

The purpose of this study was to evaluate the bone-generating ability of a new bovine-derived xenograft (S1-XB) containing hydrogel. For control purposes, we used Bio-Oss and Bone-XB bovine-derived xenografts. S1-XB was produced by mixing Bone-XB and hydrogel. Cell proliferation and differentiation studies were performed to assess cytotoxicities and cell responses. For in vivo study, 8 mm-sized cranial defects were formed in 16 rats, and then the bone substitutes were transplanted into defect sites in the four study groups, that is, a Bio-Oss group, a Bone-XB group, an S1-XB group, and a control (all n = 4); in the control group defects were left empty. Eight weeks after surgery, new bone formation areas were measured histomorphometrically. In the cell study, extracts of Bio-Oss, Bone-XB, and S1-XB showed good results in terms of the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and no cytotoxic reaction was evident. No significant difference was observed between mean new bone areas in the Bio-Oss (36.93 ± 4.27%), Bone-XB (35.07 ± 3.23%), and S1-XB (30.80 ± 6.41%) groups, but new bone area was significantly smaller in the control group (18.73 ± 5.59%) (p < 0.05). Bovine-derived bone graft material containing hydrogel (S1-XB) had a better cellular response and an osteogenic effect similar to Bio-Oss.

Histological Comparison between Biphasic Calcium Phosphate and Deproteinized Bovine Bone on Critical-Size Bone Defects

The limited options for bone repair have led to an extensive research of the field and the development of alloplastic and xenogeneic grafts. The purpose of this study was to evaluate bone repair with two bone substitutes: deproteinized bovine bone (DBB) and biphasic calcium phosphate ceramic (BCP) in critical-size defect. A total of 8-mm defects were made in the parietal bones of rabbits (n=12). The animals were divided into three experimental groups: sham (defect filled with a blood clot), DBB (defect filled with DBB), and BCP (defect filled with BCP). After the experimental periods of 15 and 45 days, the animals were euthanized and submitted to histomorphometric analysis. The total defect area, mineralized tissue area, biomaterial area, and soft tissue area were evaluated. A greater amount of immature bone tissue and biomaterial particles were observed in the BCP group compared to DBB and sham at 45 days (p<0.05). There was no difference in the qualitative pattern of bone deposition between DBB and BCP. However, the sham group did not show osteoid islands along with the defect, presenting a greater amount of collagen fibers as well in relation to the DBB and BCP groups. There was a greater number of inflammatory cells in the DBB at 45 days compared to BCP and sham groups. In conclusion, BCP and DBB are options for optimizing the use of bone grafts for maxillofacial rehabilitation. Bone defects treated with BCP showed greater deposition of bone tissue at 45 days.

Bone formation in custom-made cranioplasty: evidence of early and sustained bone development in bioceramic calcium phosphate implants. Patient series

BACKGROUND

Implant failure (IF) rates in cranioplasty remain high despite efforts to reduce the incidence. New biomaterials may be part of the solution for this problem. Formation of autologous bone in implants may reduce rates of infection and subsequent failure.

OBSERVATIONS

Four patients with calcium phosphate implants supported by titanium mesh and undergoing surgery for reasons unrelated to IF were included in this series. Samples from the implants were microscopically examined. Pathological studies proved the formation of autologous bone in the calcium phosphate implants.

LESSONS

Bone and blood vessel formation in the implants and diminished foreign body reaction to autologous bone may reduce the rates of IF.