Scaffolds For Bone Defects Research Articles

A review: In vivo studies of bioceramics as bone substitute materials

AbstractThe critical size of bone defects resulting from disease or fractures is a medical problem, usually unable to repair spontaneously by the body's healing mechanisms. Bioceramics are being used for bone tissue regeneration to stimulate the growth of bone cells and guide osseous remodeling. The three most common types of bioceramics used in bone tissue engineering (hydroxyapatite, bioactive glass, and tricalcium phosphate) were selected and studied in vivo animal models, exhibiting favorable bone formation with positive biocompatibility reactions for several animal models. In the study, an extensive review of research was conducted to assess the bone‐forming capabilities of scaffolds in bone defects and remodeling in vivo. This review aims to support a large‐scale assessment of the capabilities of in vivo studies to generate an optimal regenerative process based on an analysis of the results. In addition to providing an essential reference for the applications of bone tissue engineering, the review will assist in developing novel in vivo investigations.

Local injection of angiopoietin 2 promotes angiogenesis in tissue engineered bone and repair of bone defect with autophagy induction in vivo

To investigate the mechanism of early vascularization of the tissue engineered bone in the treatment of rabbit radial bone defect by local injection of angiopoietin 2 (Ang-2). A single 1.5 cm long radius defect model (left and right sides randomised) was constructed from 48 New Zealand white rabbits. After implantation of hydroxyapatite/collagen scaffolds in bone defects, the rabbits were randomly divided into 2 groups: control group (group A) and Ang-2 group (group B) were injected with 1 mL normal saline and 1 mL saline-soluble 400 ng/mL Ang-2 daily at the bone defect within 2 weeks after operation, respectively. Western blot was used to detect the expressions of autophagy related protein [microtubule associated protein 1 light chain 3 (LC3), Beclin-1], angiogenesis related protein [vascular endothelial growth factor (VEGF)], and autophagy degradable substrate protein (SQSTMl/p62) in callus. X-ray films examination and Lane-Sandhu X-ray scoring were performed to evaluate the bone defect repair at 4, 8, and 12 weeks after operation. The rabbits were sacrificed at 12 weeks after operation for gross observation, and the angiogenesis of bone defect was observed by HE staining. Western blot assay showed that the relative expression of LC3-II/LC3-I, Beclin-1, and VEGF in group B was significantly higher than that in group A, and the relative expression of SQSTMl/p62 was significantly lower than that in group A ( P<0.05). Radiographic and gross observation of specimens showed that only a small number of callus were formed in group A, the bone defect was not repaired; more callus were formed and complete repair of bone defect was observed in group B. The Lane-Sandhu scores in group B were significantly higher than those in group A at 4, 8, and 12 weeks after operation ( P<0.05). HE staining showed that the Harvard tubes in group B were well arranged and the number of new vessels was significantly higher than that in group A ( t=-11.879, P=0.000). Local injection of appropriate concentration of Ang-2 may promote early vascularization and bone defect repair of rabbit tissue engineered bone by enhancing autophagy.

Fabrication and evaluation of silica-based ceramic scaffolds for hard tissue engineering applications

In recent decades, bone scaffolds have received a great attention in biomedical applications due to their critical roles in bone tissue regeneration, vascularization, and healing process. One of the main challenges of using scaffolds in bone defects is the mechanical strength mismatch between the implant and surrounding host tissue which causes stress shielding or failure of the implant during the course of treatment. In this paper, space holder method was applied to synthesize diopside/forsterite composite scaffolds with different diopside content. During the sintering process, NaCl, as spacer agent, gradually evaporated from the system and produced desirable pore size in the scaffolds. The results showed that adding 10wt.% diopside to forsterite can enormously improve the bioactivity, biodegradability, and mechanical properties of the composite scaffolds. The size of crystals and pores of the obtained scaffolds were measured to be in the range 70–100nm and 100–250μm, respectively. Composite scaffolds containing 10wt.% diopside showed similar compressive strength and Young's modulus (4.36±0.3 and 308.15±7MPa, respectively) to that of bone.