| Objective To evaluate the effect of repair with PVA/n-HA+PA66biological composite material on articular cartilage andsubchondral bone.Methods①preparation and function of biological compositematerials: New type biological composite materials (PVA/n-HA+PA66)were prepered by in situ preparation and freezing-melting circleway. Inner structure,mechanical property,friction coefficientwere measured by mechanical test instrument,KRD and SEM.②Biocompatibility on biological composite material in animalbodies: The animal models of defect of articular cartilage andsubchondral bone were made up, PVA or PVA/n-HA+PA66 weretransplanted into articular cartilage defects of rabbit kneejoints. The defects with no implants were used as blank controlgroups.The macroscopic, histologial evaluation were performedat 4,8,12,24 weeks postoperatively.In the meantime,the interfaceof implants with articular cartilage and subchondreal bone wasobserved by SEM,Ⅱcollage andⅡcollage mRNA were measured byimmunolly tissue chemical method and situ hybridization method at 12,24 weeks, Mechanical properties in vivor were measured atthe same time.③Biological security of biological compositematerial after implanting into animal bodies: TO investigate theacute or chronic toxic reaction on the whole badyaboutPVA/n-HA+PA66 byabdominalcavity injection,intradermalinjection and subcutaneous implantation,then to evaluate thebiocompatibility security of new type biological compositematerial.④Transpalntation inmunoreaction on biologicalcomposite material after implanting into animal bodies: Compositematerials were impalnted into mouse subcutaneous tissue. Theamount of CD4~+,CD8~+ in spleen cells and IL-1,IL-6,TNF-αin bloodwas measured at 2,4,6 weeks,and compared with the amount offoreoperationResult①preparation and function of biological compositematerial:Composite metarials were 3D porous structure by SEMobservation, pore size was 5-400um, the upper layer connectedtightly with the lower layer by interlocking way, water-loctedrate of the upper layer was 71.6%. The upper layer materialstrength of resisting-draw is 3.42Mpa under 100mm/min pullingforce and strength of resisting press is 3.12Mpa under 3mm/minpressing force. The lower layer material was equal crystalstructure, its porosity was 61.8%. Its strength of resisting pressis 5.3Mpa under 3mm/min pressing force.②Biocompatibility onbiological composite material in animal bodies:All animalssurvived and all knee joints moved freely. Composite materials were stable and not drop. Inflammatory cells and fibroblastsexisted surround the materials at 4 week. At 8,12,24 weeksbone tissue were found growing into lower layer materials. Theupper layer materials got well with surrounding cartilage,surrounding cartilage grew into the surface of the metarials andwere not degenerat. The upper layer materials conneeted tightywith the lower layer materials; The strength of resisting lash ofcomposite materiass were 72.31N at 12week, 76.45N at 24 week underthe state of 5mm/min lashing force and reach to the level ofstrength of normal bone's resisting lash at 12 week.③Biologicalsecurity of biological composite material after implanting intoanimal body: The rats activity was normal in the acute toxicreaction on the whole body. The intradermal injection experimentwas normal. In chronic toxic reaction, rats liver and kidneyfunction was not different, compared with the control groups at12 week. The fibrous tissue and some blood vessels were foundgrowing into the porous materials and became the whole structurewith the composite materials. The rejecting reaction was not found.This indicated that composite materials have goodbiocompatibility with the surrounding tissue.④Transpalntationinmunoreaction on biological composite material after implantinginto animal body: The amount of CD4~+,CD8~+ in mouse spleen cellswas not different with the control groups at 2,4,6 weeks(P＞0.05). The amount of IL-1,IL-6,TNF-αin mouse blood was notdifferent with the control groups at2,4,6weeks (P＞0.05). Condusion: The initial experiment showed that the new typebiological composite materials PVA/n-HA+PA66 have good functionfor replacing articular cartilage and subchondral bone and havegood biocompatibility and biological security. The compositematerial have no poisonous influence and side-effect onanimals, and have no abnormal transplantation immunoreaction. Sothe new type composite materials have potential appicaltion valuein clincal works. But the mechanical properties and wearing problemof PVA are necessary to be solved.
|
PDF Full Text Request