RESUMO
BACKGROUND:The physiochemical properties and bioactivity of composite scaffolds can be altered by different crosslinkers.OBJECTIVE:To compare the physiochemical properties and bioactivity of composite scaffolds composed of β-tricalcium phosphate and gelatin,which are crosslinked by 1％ genipin or gluteraldehyde,respectively.METHODS:Porous scaffolds composed of β-tricalcium phosphate and gelatin were made by phase separation/freeze-drying technique.Crosslinking time was 72 hours when genipin acted as a crosslinker and 24 hours when glutaraldehyde as a crosslinker.Physiochemical properties including porosity,degree of cross-linking,in vitro swelling ratio,degradation rate and compressive strength were detected.Bioactivities analyses were performed through co-culturing rabbit periosteal osteoblasts with 25％,50％ and 100％ scaffold extracts for 24,48,72 hours.The proliferation rate and cytotoxicity gradation were evaluated.In addition,bilateral 8-mm skull defects were made in 18 rabbits and repaired with scaffolds crosslinked by genipin or gluteraldehyde,respectively.Gross observation,X-ray analysis and histological observation were performed at 4,8 and 12 postoperative weeks.RESULTS AND CONCLUSION:(1) The porosity,compressive strength and maximum compressive force showed no statistical difference between the two crosslinker groups.Compared with the gluteraldehyde group,higher degree of crosslinking and lower swelling ratio and degradation rate were observed in the genipin group (P ＜ 0.05).(2) In the genipin group,less than 50％ growth inhibition was observed when co-cultured with 100％ scaffold extract for 24 hours.Thus,the cytotoxicity was graded as 2,and the remains were graded as 1 or 0.In the gluteraldehyde group,excessive 50％ growth inhibition was observed when co-cultured with 100％ scaffold extract for 24 hours,and the cytotoxicity was graded as 3.For 25％ and 50％ subgroups (culture for 24 hours) and 100％ subgroup (culture for 48 hours),the cytotoxicity was graded as 2,and the remains were graded as 1.(3) X-ray and histological observation showed the in-growth of new bone tissues from the periphery of the defect and the scaffold degraded centripetally.New bone formation was better in the genipin group than the gluteraldehyde group at 8 and 12 postoperative weeks (P ＜ 0.05).To conclude,both genipin and gluteraldehyde can be used as crosslinkers to prepare the composite bone scaffold composed of β-tricalcium phosphate and gelatin.Two scaffolds have similar physicochemical properties;however,the former has a superior bioactivity except for a longer time for crosslinking with genipin.