Scaffold degradation during bone tissue reconstruction in Macaca nemestrina mandible

Objective: To examine the degradation of three scaffolds composed of hydroxyapatite/tricalcium phosphate (HA/TCP) with 70:30 ratio, HA/TCP with 50:50 ratio, and HA/TCP/chitosan scaffold as analyzed by the RNA expression of matrix metalloprotease 2 (MMP2), interleukin 13 (IL13), and tartrate-resistant acid phosphatase (TRAP) genes. Methods: The three tested scaffolds and dental pulp stromal cells (DPSCs) were transplanted into the mandibular bone defect of six young male Macaca nemestrina. Defect on the left mandible served as the experimental group and the right mandible served as control group (split mouth design). The biopsies were retrieved at 0, 2, and 4 weeks after cell-scaffold transplantation. The expression of MMP2, IL13, and TRAP was analyzed by real-time PCR (RT-PCR). Results: The inflammatory cells were still detected in areas where active bone and blood vessel formation occurred. The remnants of scaffold biomaterials were rarely seen. The expression of MMP2, IL13, and TRAP was observed in all samples. Their expressions were increased at week 4 and the decrease of TRAP gene expression in the experimental group was found higher than the control group. TRAP gene in the HA/TCP/chitosan group was found to be the highest at week 2 and lowest at week 4. Conclusions: Degradation of the scaffold did not induce higher inflammatory response compared to the control yet it induced more osteoclast activity.