Experiment Study For Resurfacing Cartilage Defect With New Biphasic Biomaterials

As the economic improvement,the incidence of severe trauma accelerate so rapidly, as a result, cartilage defect influence about millions patients. According estimate,there are several hundred thousand people need artificial joint replacement.The development of Cartilage materials and tissue engineering will improve patients' life quality,delay the time of surgery and enhance cost-effect of medicine resource. All these advantages is more meaningfully for the economic level and medical service status .So, keep up with the update of the development direction of cartilage materials, research biomaterial for repair or resurface cartilage lesion with good quality and high cost-effect rate will be a bright future for the clinical application.On the basis of reviewed the literature, we concluded that a lot of research demonstrate the long-term outcome will last until the subchondral bone be repaired and the whole architecture and composite be restored. In fact, we should review the articular cartilage and subchondral bone as a complete functional unit ,not two kind separate or isolate tissues. The biphasic material of cartilage and bone not only can refill the defect, but also act as the physical function of cartilage and subchondral bone. Since, this kind of material get high light of researcher and doctors. Based the architecture and characters of cartilage, the perfect resurface material must has quality as following, friendly biomechanic qulity , low friction and anti-wear feature, induce capability of chondrocytes and good bone ingrowth potential ,biocompatibility.So, we try some step to do the research about the preparation and biomechanic test of biphasic material ;experiment of resurface defect in vivo; subcutaneous implant test to assess the biocompatibility. There are the result as following:1. Preparation and Biomechanic test of Biphasic material1 .PVA is a kind of permeable material with muti-microporous structure similar to natural cartilage and a lot of water located in the micropores. With the load-bearing, liquid in the pores can easily influx and efflux and becomes lubricant when effluxes.PVA hydrogel was obtained with repeated freeze-drying. The freeze-drying treatment can increase the crystalinity and the mechanical property of PVA.For example, when the concentration of PVA was 20%, the tensile strength reached 5.9MPa after 12 hours dehydration, which is similar to human cartilage.2. n-HA/PVA composite hydrogel is prepared by in situ preparation. By controlling the content of PVA, n-HA and water, composite hydrogels with differentproportion were prepared. n-HA was distributed in the PVA matrix uniformly, and the composite had goodstability and processability.3. The integrative interlocked biomaterial for bone and cartilage repair was made by combining bone tissue-engineered 60%n-HA/PA66 composite scaffold with PVA and n-HA/PVA hydrogels used as cartilage prosthesis. The material was prepared by penetrating the n-HA/PA66 scaffolds with PVA hydrogel under the condition of high temperature and pressure.2. Experiment of Resurface Defect in vivoWe divided thirty Newzeland Rabbit into three group and creat cartilage defect of diameter 4 mm on bilateral knee femoral trochlea groove: Group A,unilateral implant with PVA/n-HA combine n-HA/PA66 cylinder prosthesis, the other lateral leave untreated; Group B,unilateral implant with PVA/n-HA cylinder prosthesis, the other lateral leave untreated; Group C,unilateral implant with PVA/n-HA combine n-HA/PA66 cylinder prosthesis,, the other lateral implant PVA/n-HA cylinder prosthesis. According the HE,MASSON,toluidine blue stain and immunohistochemical of type I and II collagen ,situ hybrid of type II collagen, and histological score system of modified Pineda score and ICRS system, we demonstrate the biphasic material have better resurface outcome than the monophasic and control.We assure the good repair result due to repair the cartilage and subchondral bone spontaneously.3. subcutaneous implant test to test the biocompatibility and correlation between the material and inflammatory cytokinesWe separate 24Wistar mouse into implant group,surgery intervention group and control group.After 1 and 3 weeks ,we test th IL-1 and Il-6 level in the spleen and tissue stain. The tissue result shows that the material have friendly biocompatibility,no signs of infection,no wound delay healing. The result of IL-1 and IL-6 display that during the early stage of implant ,the inflammatory reaction is slight,the level between the three group has significance difference,P<0.05. The difference between the implant group and surgery intervention group should be due to the material. The material have good biocompatibility.