A New Type Of Calcium Phosphate Granules In The Treatment Of Rabbit Femoral Head Necrosis

BackgroundOsteonecrosis of femoral head(ONFH)is a common orthopedic disease.In surgical treatment,bone grafting is usually carried out by fulfilling autogenous bone,allogeneic bone or bone substitution materials into necrosis areas to facilitate healing.Because calcium phosphate ceramic consists of calcium and phosphorus and is similar to bone tissue in chemical composition,it is regarded as a potential graft and has good prospect.In this study,we try to create a new calcium phosphate ceramic which has suitable composition,appropriate pore size and satisfied degradation rate,to provide another effective therapy for ONFH.MethodsWe select ?/?-tricalcium phosphate and polyethylene glycol as main ingredients to make calcium phosphate particles.Thereafter,we use X-ray diffraction,scanning electron microscopy and Micro-computer tomography to detect particles' component and properties.Model of ONFH is established in rabbits and particles are filled into necrosis areas.At the time of one month and two months postoperatively,Micro-computer tomography is conducted to evaluate the imaging situation and calculate the bone density of femoral head.Histopathological examination is completed by hematoxylin-eosin staining and Sirius Red staining.Extract liquid made from particles is used to culture mouse preosteoblasts MC3T3-E1 to detect the influence on proliferation by CCK-8 method.Extract liquid is also used to culture human mesenchymal stem cells,and followed by alkaline phosphatase staining and alizarin red staining,the ability of osteogenic differentiation can be observed.Results1.X-ray diffraction indicates particle is formed by hydroxyapatite,a-tricalcium phosphate and ?-tricalcium phosphate.Under scanning electron microscopy,we find hydroxyapatite crystalloid around the rugged surface of particles,and pores exist not only in the inside,but also at the surface of the particles.Micro-computer tomography shows most pore size is near 0.11mm.2.In vivo experiments:The establishment of the model of ONFH in rabbits is successful,and from radiography we can see a channel reaches femoral head exactly.From the imaging shown by Micro-computer tomography,there are newborn trabeculae growing gradually in necrosis areas in treatment group,but nearly no newborn trabeculae are found in control group.Meanwhile through calculation we get the conclusion the bone density of treatment group is much higher than that of control group both at one month and two months postoperatively.As a result of hematoxylin-eosin staining,in treatment group we find a lot of trabeculae where many bone lacunae and osteocytes exist;in control group only a few trabeculae could be observed and empty lacunae are obvious.For Sirius Red staining,in treatment group we can see plenty of highlighted orange fibers with strong refractivity;in control group the amount of such fibers decreases significantly.3.In vitro experiments:After testing by CCK-8 method,the optical density of control group is much higher than that of treatment group and this result has significant statistical difference.Meanwhile we notice the optical density of treatment group is increasing gradually day by day(P<0.05).After alkaline phosphatase staining and alizarin red staining,the positive rate of treatment group is significantly higher than that of control group.ConclusionThis new type of calcium phosphate particles can improve the ability of osteogenic differentiation of human mesenchymal stem cells,and is effective to cure osteonecrosis of femoral head in rabbits.Besides it has appropriate biocompatibility and has great potential to treat osteonecrosis of femoral head in humans.