Abstract: BACKGROUND: The shapable bone filling materials currently used in clinic are mainly composite materials composed with xenogeneic bone derived from calf bone and collagen. However, there is an animal ethical controversy because its inorganic ingredients are derived from slaughtered calves. It is necessary to find a safe, effective and shapable bone scaffold material, which not only can avoid ethical problems but also has excellent osteogenic properties.
OBJECTIVE: To prepare composite scaffolds with excellent plasticity and ability in repairing bone by chemically cross-linking collagen with granules of calcined antler cancellous bone. 
METHODS: Calcined antler cancellous bone granules were prepared by defatted and deproteinized process and combined with calcination after removal of the antler cortical bone. Calcined antler cancellous bone/type I collagen composite scaffolds were fabricated with the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide/N-Hydroxysuccinimide cross-linking method. In 10 adult Sprague-Dawley rats, a 5-mm sized full-thick bone defect was prepared on both sides of the sagittal suture of the skulls. Bio-Oss/Collagen® composite scaffolds were implanted into the defect on the left side (control group) and calcined antler cancellous bone/collagen composite scaffolds were implanted into the defect on the right side (experimental group). Hematoxylin-eosin staining and Masson’s trichrome staining were performed in skull specimens at 4 and 12 weeks after the implant operation. 
RESULTS AND CONCLUSION: (1) Four weeks after the operation, hematoxylin-eosin staining showed that new bone was formed in the bone defects in both groups, but not completely healed. Osteoblasts were seen around the implanted materials, and there were more osteoblasts around the materials in the experimental group. Masson’s trichrome staining showed that there were new collagen fibers arranged regularly and irregular bone marrow cavity around the materials of the two groups. (2) At 12 weeks after the operation, hematoxylin-eosin staining showed that the bone defects healed well in both groups; the edge of the defect was completely fused with the new bone; and the residual material was surrounded by the new bone. The new bone structure in the experimental group was dense and the degree of remodeling was high. (3) To conclude, our findings revealed that the calcined antler cancellous bone/collagen composite scaffolds are provided with good plasticity, osteoconductivity, histocompatibility and excellent bone repair effect, and can be used as a potential shapable bone filling scaffold material.

Key words: bone defect repair, bone regeneration, antlers, calcined bone, collagen, plasticity, scaffold, bone filling material