| objective: To explore the effect on degradation and osteogenesis of CPC/PLGA composite contaning RANKL in vivo.Methods: PLGA microspheres were prepared by a double emulsion technique,and RANKL was absorbed into PLGA microspheres by incubation of 0.2g PLGA microspheres with 5?g RANKL solution for 30 minutes with subsequent lyophilization for 24 hours,and then mixed to CPC at the mass ratio of CPC:PLGA=4:1.18 male and adult SD rats(weighting between 290 and 310grams)were used to establish femoral condyle lacunar defects and divided into 3groups via different implantation: A :experimental group(bone defects implanted CPC/PLGA composited with RANKL),B: control group(bone defects impla-nted CPC/PLGA),C: blank control group(did not implanted any material in bone defects).The femoral condyle were separately collected after 4,8 and 12 weeks,to analyze the intracorporal degradation and new bone reaction via gener-al observation and histological analyses.New bone tissue ratio was statistically analyzed by softwares of Image pro plus 6.0 and SPSS16.0 respectively.Result : During experiments,all SD rats had a normal postoperative recovery,the implantation's foreign body reaction was weak and there were no sign of inflammation of swelling and purulency on incision and no noticeable suppressed appetite,anomalous activities was observed.Histological examination :(1)At 4 weeks post-operation: In CPC/PLGA+RANKL group,abundant of CPC had degraded at the edge of the defect,and replaced by newly formed bone,cord-like new bone tissue intertwined into a network,and growed into the defect center.It was observed that a small amount of CPC was degraded at the edge of the defect,and the amount of new bone tissue produced was less and only at the margin in the CPC/ PLGA group.There is only a small amount of cord-like or island-like new bone tissue scattered in the blank group.(2)At8 weeks post-operation: In CPC/PLGA+RANKL group,PLGA microspheres were degraded,CPC degradation is more obvious than 4weeks,and the internal CPC of the material has also been degraded,replaced by new bone tissue,making the original boundary difficult to identify.In CPC/PLGA group,PLGA microspheres were also degraded,the new bone tissue growed to the defect center,and the bone mass is significantly increased than 4weeks.The amount of new bone tissue generated in the blank group was increas-ed,which was cord-like or small pieces.(3)At 12 weeks post-operation: In CPC/PLGA+ RANKL group,most of the implant materials had degraded,only little part of CPC was remained in the center or with diffused distribution on the edges and regenerated new bone was cord-like arrangement or Connected into a net.Its similar to CPC/PLGA+RANKL group,just part of CPC was remained among the compound,the structure of implant materials were so loosened that its original completeness was disappeared in CPC/PLGA group.In blank controlgroup,much more newly formed bone which grow to the center was observed when compared to the 8 weeks,but the defect was not healing completely.Analysis of new bone area ratio:(1)after 4 weeks: the ratio of new born area CPC/PLGA+RANKL group(9.66±3.84)% > blank control group(5.76±1.58)%>CPC/ PLGA group(4.01±3.51)%,CPC/PLGA+RANKL group and CPC/PLGA group had significant different(P<0.05),blank control group had no significant different compared to CPC/PLGA+RANKL group and CPC/PLGA group respectively(P>0.05).(2)after 8 weeks: the ratio of new born area CPC/PLGA+RANKL group(25.01±7.32)% > CPC/PLGA group(23.37±4.13)%>blank control group(6.11±5.37)%,CPC/PLGA+ RANKL group and CPC/PLGA group had significant different(P>0.05),blank control group had significant different compared to CPC/PLGA +RANKL group and CPC/PLGA group respectively(P<0.05).(3)after 12 weeks: the ratio of new born area CPC/PLGA+RANKL group(23.54±15.12)% > CPC/PLGA group(16.78±7.86)% > blank control group(11.73±6.53)%,there were no significant different among the three groups(P>0.05).Conclusion: The addition of RANKL promoted the early degradation and osteogenesis of CPC / PLGA composite. |
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