High-strength mineralized collagen artificial bone

Mineralized collagen （MC） is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal＇s cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in v/vo implantation assay demonstrated good biocompatibility of the material, and in v/vo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load- bearing sites.

Mineralized collagen artificial bone repair material products used for fusing the podarthral joints with internal fixation—a case report

In this study,we reported a case with collapse and subluxation of metatarsal-cuneiform joint,navicular-cuneiform joint with subluxed the right first metatarsophalangeal joint.The injured medial column was internally fixed with compression arthrodesis.The fusion site was firmed up with BonGoldVR Bone Sponge and Bone Putty.The prognosis of fused navicular-cuneiform joint and metatarsal-cuneiform joint were examined by X-ray shortly after surgical operation and followed up 2,4,6,9 and 13 weeks after the surgical operation.Themedial column was perfectly fused by compression arthrodesis.These results justified and favored the application of mineralized collagen as an excellent alternative to autograft in fusing the podarthral joints with internal fixation.

The role of crystallinity on differential attachment/ proliferation of osteoblasts and fibroblasts on poly （caprolactone-co-glycolide） polymeric surfaces

The objective of the present study is to systematically evaluate the role of polymer crystallinity on fibroblast and osteoblast adhesion and proliferation using a series of poly（caprolactone-co-glycolide） （PCL/PGA） polymers. PCL/PGA polymers were selected since they reflect both highly crystalline and amorphous materials. PCL/PGA polymeric materials were fabricated by compression molding into thin films. Five compositions, from PCL or PGA to intermediate copolymeric compositions of PCL/PGA in ratios of 25：75, 35：65 and 45：55, were studied. Pure PCL and PGA represented the crystalline materials while the copolymers were amorphous. The polymers/copolymers were characterized using DSC to assess crystallinity, contact angle measurement for hydrophobicity, and AFM for nanotopography. The PCL/PGA films demonstrated similar hydrophobicity and nanotopography whereas they differed significantly in crystallinity. Cell adhesion to and proliferation on PCL/PGA films and proliferation studies were performed using osteoblasts and NIH-3T3 fibroblasts. It was observed that highly crystalline and rigid PCL and PGA surfaces were significantly more efficient in supporting fibroblast growth, whereas amorphous/flexible PCL/PGA 35：65 was significantly more efficient in supporting growth of osteoblasts. This study demonstrated that while chemical composition, hydrophobicity and surface roughness of PCL/PGA polymers were held constant, crystallinity and rigidity of PCL/PGA played major roles in determining cell responses.