Effect Of POC-HA Tissue-engineering Bone On Rabbits Posterolateral Spinal Fusion

Background:The regeneration of the bone tissue is very strong.In a good biological micro environment,the vast majority of bone injury can fully heal[1].Over the past ten years,the cure rate of bone injury has been greatly improved.But,there are still some bone diseases those cure rate remains to be improved.The reason of restricting the cure rate of diseases is lack of proper bone graft materials[2].Taking the bone from iliac bone is easily leading to complications.We urgently need to develop a kind of tissue-engineering bone that is cheap and safety.In the past,a large number of tissue-engineering biomaterial created and applied to clinical study.We can be divided into three generations[3].Firstly,inert biological materials,are used to fill the tissue defect.They contain stainless steel,cobalt-chromium alloy,titanium alloy,nickel-titanium memory alloy,acrylic resin,silica gel,PE,PP and PMMA[4].The first generation of tissue-engineering biomaterials applied to clinical study has a history of more than half a century.There are much more nonspecific protein deposition on the biomaterial surface after transplantation.It is very hard to restore.In order to overcome the lack of the first generation of biological materials,the second generation of biological materials were created in 1980s.They could be gradually absorbed with the degradation of biomaterial in tissue repair process[5].They certain glass ceramic,PGA,PL A,PCL[6].The third generation of tissue engineering biomaterial comprehensive previous biological activity of biological materials and biological characteristics of absorbability.Their degradation products also has biological activity and induce cell specificity reaction in molecular level.In the past 60 years,With the progress and mutual cooperation of material science,engineering,physics,chemistry,physiology and medicine,there are a lot of new bone tissue engineering biomaterial were created.They were widely used in the clinical treatment of repairing bone defect,such as HA,TCP,PGA-HA,PLA-HA and PCL-HA.They were created through the simulation of the human bone.Regretfuuly,with the continuous improvement of synthetic technology,inorganic polymer composite materials is still faced with some problems.Firstly,restricted by the chemical structure of polymer materials,they can composite only 30%HA[10].They are more different from human bones.Secondly,they degrade slowly and their degradation products cause inflammation[11].Biological materials cannot be completely integrated and the surrounding bone tissue preferably.To find out the way to overcome the above disadvantages polymer composites,the experimental design of the citric acid and hydroxyapatite as the main raw material for polymer composites POC-HA,was observed with the tissue-engineering bone in vitro and in vivo characteristics,to explore whether there are good prospects for development in the field of orthopedics.Objectives:Through synthetic bone tissue engineering based on POC-HA,we observe the ultrastructure of the surface properties,degradation ability in vitro and cell biocompatibility.We use it for rabbit spinal posterolateral fusion,observe the fusion effect,and compared with autologous bone graft.The purpose of this study is looking for a tissue-engineering bone which can replace autologous bone.Methods:Using SEM to test the POC-HA tissue-engineering bone after cleaning,fixing,drying,spraying metal.Useing SEM to observe the BMSC which adhesion on surface of POC-HA tissue-engineering bone that was treated by cobalt-60 sterilization technique.Puting the POC-HA tissue-engineering bone into the PBS for 20 weeks and observing its degradation.Testing the PLF effect of the rabbits through Micro-CT scanning,bone analysis and biomechanics.Observing the growth of new bone and its nourish blood vessels through HE staining and Masson staining.Results:1.The microcosmic surface structure of POC-HA tissue-engineering bone The POC-HA tissue-engineering bone has porous microstructure and 70%porosity.The pore diameter is 200-500mm.The microstructure of surface is rough,and it is benefit for cell adhesion.2.The ability to composite cells of POC-HA tissue-engineering bone BMSC of rabbits was co-cultured with POC-HA tissue-engineering bone.The viability of BMSC which is on the surface of tissue-engineering bone is very good.We can see the rabbit BMSC completely attached to the surface of the POC-HA tissue-engineering bone,a spindle flat and stretched out a large number of filopodia attached to the surface of the material through SEM scanning.3.The degradation of POC-HA tissue-engineering bone in vitro Testing the quality of a tissue-engineered bone which was put into the PBS in 2 weeks,6 weeks,12 weeks and 20 weeks.The degradation rate calculated by the formula:Mass lose(%)=wo-wt/wo × 100%.The weight of POC-HA tissue-engineering bone is lost volume of about 8.4%in 20 weeks.4.Effect evaluation of rabbit PLF by Micro-CT scanning The newborn callus of tissue-engineered bone is little in 5 weeks.There is no bony fusion between the transverse.New bone callus of tissue-engineered bone increased slightly,and tissue-engineering bone becomes spars and degradation in 10 weeks.The PLF is not completely.New bone callus of tissue-engineered bone is the most of all,and it is significantly reduced in 15 weeks.The bony fusion of intertransverse is very strong.Most of the ilium is absorbed reconstruction,and The bony fusion of intertransverse is very strong in 15 weeks.We choose BMD and BV/TV from bone analysis of selected areas to evalute the new bone.By comparing the 5 weeks,10 weeks,15 weeks tissue-engineering experimental group,BMD and BV/TV are significantly different among the three groups(P<0.05).By comparing the 15 weeks bone tissue engineering group and 15 weeks autogenous bone graft group,BMD and BV/TV are significantly different between the two groups(P<0.05).5.Effect evaluation of rabbit PLF by biomechanicsThrough three-point bending tests on samples,we can get the maximum stress.By comparing the 5 weeks,10 weeks,15 weeks tissue-engineering experimental group,the stress is significantly different among the three groups(P<0.05).By comparing the 15 weeks bone tissue engineering group and 15 weeks autogenous bone graft group,the stress is not significantly different between the two groups(P=0.064).6.Histological evaluation of POC-HA tissue-engineered boneHE staining A large number of cells can be seen crawling on tissue engineering bone,and the cells secrete a large number of extracellular matrix in 5 weeks.Its vitality is very good.We can see an increase in the number of cells which are around the tissue-engineering bone,and some cells in the exuberant phase of cell division in 10 weeks.There are a lot of new bone and nourish the blood vessels around the tissue-engineering bone in 15 weeks.The emergence of new bone can prove a strong osteoinductive of POC-HA tissue-engineering bone.Masson staining There are cells attached to the bone tissue engineering and there appear woven bone in 5 weeks.The cell division is very exuberant in 10 weeks.The new bone which was stained dark blue tightly chelated with residual tissue-engineering bone in 15 weeks.Conclusion:Our findings suggest that POC-HA tissue engineering bone has porous structure,good biocompatibility and tissue compatibility.From the PLF of rabbits,POC-HA tissue engineering bone has obvious osteoconductive and osteoinductive,and it is a very good development prospects of the bone graft substitute.