Abstract
OBJECTIVE: To study the ectopic osteogenesis and biocompatibility of bone morphogenetic protein 2 (BMP-2)-derived peptide P24 loaded chitosan-4-thio-butylamidine (CS-TBA) hydrogel. METHODS: First, the CS-TBA/hydroxyapatite (HA) solution was prepared by using chitosan, 2-iminothiolane hydrochloride, and HA. Then, the different amount of P24 peptides were added to the CS-TBA/HA to prepare the CS-TBA/5%P24/HA and CS-TBA/10%P24/HA solutions. Finally, β-glycerophosphate disodium (β-GP) was added to the CS-TBA/HA, CS-TBA/5%P24/HA, and CS-TBA/10%P24/HA to prepare the CS-TBA/HA/β-GP, CS-TBA/5%P24/HA/β-GP, and CS-TBA/10%P24/HA/β-GP hydrogels, respectively. Eighteen Sprague Dawley female rats were randomly divided into 3 groups ( n=6), which were injected into the back muscle pouches with equal volume CS-TBA/HA/β-GP hydrogel (group A), CS-TBA/5%P24/HA/β-GP hydrogel (group B), and CS-TBA/10%P24/HA/β-GP hydrogel (group C). The animals were sacrificed at 4 and 8 weeks and conducted micro-CT. The ability of biodegradation and osteogenesis of hydrogl was detected by trabecular thickness (Tb.Th), trabecular number (Tb.N), bone mineral density (BMD), and histological staining (HE and Masson). RESULTS: All the rats in 3 groups survived to the time point of the harvest. Micro-CT results showed that the new bones gradually increased in each group after operation. At the same time, the new bone formation was more obvious in groups B and C than in group A, and with the increase of P24 concentration, new bone formation in group C was much more than that in group B. The Tb.Th, Tb.N, and BMD increased gradually in 3 groups, and the differences between 4 and 8 weeks were significant ( P<0.05) except the Tb.Th in group A. At different time points, the Tb.Th, Tb.N, and BMD were significantly higher in groups B and C than in group A ( P<0.05), and in group C was higher than in group B ( P<0.05), showing significant differences between groups. Histological staining showed that the materials of groups B and C were biodegradable, and the osteogenic effect was increased with the increase of P24 concentration. CONCLUSION: P24 peptide can improve the ectopic osteogenesis of CS-TBA hydrogel, and the 10% concentration is more effective.