Mechanical Property And Bone Response In Vivo Of The Calcium Phosphate Cement/electrospun Plga Nanofiber Membrane Composite

OBJECTIVE To explore the new method of composite the calciumphosphate cement and the PLGA electrospun nanofiber membrane,and then toexplore the mechanical property、biocompatibility and bone response of theCPC/PLGA composite.METHODS Vitro experiment:Used a method of coaxial involvement,composited the CPC and the PLGA membrane.Prepared specimens respectivelyof CPC/PLGA and CPC two groups, the size of specimens was6mm×6mm×20mm, tested the mechanical properties of the materials by the three-point flexuraltest.Vivo experiment:27Newzealand white rabbits，prepared the diameter of4.4mm,8mm deep cylindrical bone defect in two sides of femoral condyles，divided into CPC/PLGA composite group, CPC group and the blank controlgroup. each group of9rabbits.Animals were sacrifice at4、8、12weeks postoperation, made general observation、X-ray、histological and SEM observationon the biocompatibility and bone response of the polymer PLGA electrospunnanofiber membrane/CPC composite.RESULTS Vitro experiment:Compared with the CPC group, the WOF of CPC/PLGA group was improved, the Modulus of elasticity and bending strengthcompared with the CPC group, the difference was no statistically significant（P＞0.05）.The WOF of CPC/PLGA was1820J/m2,the bending strength was3.98MPa，Modulus of elasticity was1.97GPa, the WOF of CPC was25.13J/m2，thebending strength was3.09MPa, modulus of elasticity was3.17GPa.Vivo experiment: General observation: The Animals recovered smoothly,without wound infection. Life habits were normal during healing process.Animal taking food, moving were normal, body weight examination were alsoregular, and it was not discovered toxicity and other abnormal reaction.Histological analysis,Basic Fuchsin staining of sections shown that:(1)Blank control group:4Weeks, a small bone tissue grow along the bone defectedge;8weeks, trabecular was scattered in the bone defect;After12weeks,lamellar trabecular was observed in the bone defect, but it failed to completelyheal.(2)CPC group:4weeks,CPC has no degradation, new bone tissue growthalong the surface of the CPC;8weeks, CPC has no obvious degradation, thesurface of the CPC was overgrown by new bone tissue;in12weeks, CPCcombined tightly with the new bone tissues, but just a small amount ofdegradation in the edge of CPC.(3) CPC/PLGA group:4Weeks, most of themembrane of the CPC/PLGA composite were degraded, a small amount of thebelt-like new bone tissue growth along the surface of the CPC;8weeks, the newbone tissue increased obviously,gradually filled up the empty spaces whichcreated by membrane degradation;12weeks, the matured new bone tissue filledup all empty spaces in the composite. There was no obvious tissue inflammatoryreaction during the three observation points.New bone volume (NBV) analysis showed:(1) CPC/PLGA group: From4weeks to12weeks, with the increase of observation time, new bone volume showed a decreasing trend. The NBV:12W was42.16%＞8W was41.03%＞4W was28.58%,the difference was statistically significant in4W、8W（P＜0.01), the difference was no statistically significant in8W、12WCPC（P＞0.05）;(2)CPC group：in4weeks,The NBV was9.10%;8weeks, the quantity of newbone were down a bit;12weeks,bone tissue generated a little,the NBVwas17.66%.The difference was no statistically significant in4W、8WCPC（P＞0.05）, the difference was statistically significant in8W、12W（P＜0.01);(3)Blank control group:from4weeks to12weeks, with the increase of observationtime,the NBVwas increased.4weeks was15.67%＜8weeks was23.64%＜12weeks was24.92%.The difference was statistically significant in4W、8W（P＜0.01). The difference was no statistically significant in8W、12W（P＞0.05）.Analysis between groups showed:From4weeks to12weeks, the NBV wasCPC/PLGA group＞blank control group＞CPC group, the difference wasstatistically significant in3groups（P＜0.01).CONCLUSION1. Use a method of coaxial involvement, composited the CPC and the PLGAelectrospun nanofiber membrane, the PLGA membrane could effectivelyimproved the toughness of CPC, and the composite has good mechanicalproperty.2. The PLGA electrospun nanofiber membrane/CPC composite has goodbiocompatibility and bone repair ability. It promised to be a good artificial bonesubstitute materials.