Osteoinduction following Implantation of Collagen Hydrogel-sponge Composite

Objectives: We prepared a collagen hydrogel-sponge composite which would serve as a regenerative scaffold. The aim of this study was to examine the osteoinductive ability and biocompatibility of the collagen hydrogel-sponge composite after implantation in rat.

Methods: The collagen hydrogel-sponge composite consisted of 1.5% collagen hydrogel cross-linked by ascorbate and Copper ion and 4% FC-HAC sponge prepared by mixing fibrillar collagen with heat-denatured collagen at a ratio of 9:1 in weight (5󬊃 mm). The collagen hydrogel was injected into the FC-HAC sponge, and the construct was then immersed in PBS to acquire viscoelastic property at neutral pH. Sixteen rats were divided into two groups in this study. In the experimental group, collagen hydrogel-sponge composite was implanted in a cranial bone defect (5󬊀.3mm). In the control group, no implantation was performed. Three days and 2 weeks after surgery, the specimens were prepared for histologic analysis.

Results: In the experimental group at day 3, proliferation of osteoblastic and fibroblastic cells was observed in the implanted collagen material. Inflammatory cells and macrophages were scantily observed around the defect area. At week 2, the area of new bone in experimental and control groups was 6.27 mm² and 3.25 mm², respectively. New bone formation in the experimental group was significantly promoted as compared to the control group (p<0.01). Height of new bone at week 2 was 1.22 mm in the experimental group, compared to 0.68 mm in the control group (p<0.01). No remnants of the collagen material were observed in the experimental group at week 2.

Conclusion: Application of collagen hydrogel-sponge composite stimulated bone augmentation with high biocompatibility. The collagen material may serve as a scaffold for bone engineering.