| ObjectiveTransforming growth factor beta1(TGF-beita1)/chitosan hydrogel microspheres,nano hydroxyapatite/collagen scaffold materials and nano hydroxyapatite/collagen scaffold materials combined with transforming growth factor beta 1(TGF-beita1)/chitosan hydrogel microspheres were prepared in the lab.Then respectively with simple support material and load transforming growth factor beta 1(TGF-beta 1)/chitosan scaffold materials of controlled-release microspheres used in rabbit radial bone defect repair.By observing the results of bone defect area osteogenesis repair,to confirm the ability of nano hydroxyapatite/collagen bone repairing rabbit radial bone defect and the effect of transforming growth factor-beta 1 in the process of bone repair.For application of bone tissue engineering methods to repair large bone defect in the clinical search for an effective method.Methods1.TGF-? 1/chitosan sustained release microspheres were prepared by the method of emulsion.Particle appearance,drug loading capacity and encapsulating efficiency were observed to study the properties of the microspheres.2.Preparation of nano hydroxyapatite/collagen bone and nanometer artificial bone/TGF-beta 1 composite chitosan hydrogel microspheres of artificial bone,and the two kinds of artificial bone scanning electron microscopy(sem)observation,porosity and mechanical properties were determined.3.Choose 45 ordinary New Zealand white rabbits,bilateral radial 10 mm bone defect model was established by operation.Will be pure nano hydroxyapatite/ collagen bone scaffold implanted on the left side of the radial bone defects,set as control group.Will load transforming growth factor beta 1(TGF-beta 1)/chitosan hydrogel microspheres of nano hydroxyapatite/collagen scaffold implanted on the right side of the radial bone defect,the setting of the experimental group.The 2nd weeks,4th weeks,6th weeks,8th weeks,12 nd weeks period after surgery,9 was selected randomly from 45 different animals to be put to death,X-ray pictures of double forelimbs,bone mineral density measurement of defect surgical area and analysis of pathological histology were done to assess the bone defect repair situations in different periods.Statistical analysis was done to the different data of the experimental group and the control group,and to confirm the different effects of the two different support materials in repairing bone defect.ResultsTGF-?1/chitosan sustained release microspheres were in powder form and the color was faint yellow.The microspheres were spherical in shape,had a smooth surface,and the diameter was 5 ? m by scanning electron microscopy.The encapsulation efficiency of TGF-?1 was 79.5% and the drug loading capacity was 22.9?g/g.From the release experiments,the rate was fast in 12 hours and became slowly step by step,the amount of release was 55.5% at the 6th day.General observation: 2 weeks after surgery,the surgical site in the experimental side outline of scaffold materials are clear,the feeling of touch its hardness increases,its and rabbit radius at both ends of the connecting parts connected firmly.Stent materials outline is clear,the control of local touch has no obvious harden and connection parts connection without the experimental side and firm,but not shift condition;4 weeks after the surgery,slit the outline of scaffold materials have not obvious,the experimental side have see outline the surgical site.Artificial bone with the host bone end between more closely,transplant material surface tactility more hard.Controlled side nanometer between bone and host bone compact connection degree and the degree of hard group is poor;6 weeks after surgery,the side of the artificial bone with the host bone end can touch and uplift between callus,quality of a material to harden.Control lateral support material and radius junction can also hit a newly formed callus,but its size and hardness are not as good as the experimental side;8 weeks after the surgery,the experimental side scaffold outside also harden and form a cladding sample structure,support material and radius on the border touches more hard callus formation and connection parts has very strong,controlled side also can touch and hard cladding and callus,but its hardness is not as good as the experimental side,the connection is strong;12 weeks after surgery,the side of the bracket Cai Liao Chu external contact has been very hard,at the junction of callus has not hit,the operation area of bone and host bone contact has very similar to that of control side is worse than the experimental side.Analysis of the X-ray examination: In the 2nd week after surgery,osteogenesis performance could be observed on the X ray in the experimental sides,the osteogenesis of bone defect part less than 25%,the junction has a few bone callus taking shape,boundaries blurred,bone reconstruction was not seen.In the 4th week after operation,the experimental sides had the osteogenesis of bone defect part more than 25%,the junction has some callus formation,boundaries more blurred,and the bone reconstruction was not seen.In the 6th week after operation,the experimental sides had the osteogenesis of bone defect part more than 50%,the junction has much callus formation,boundaries nearly disappeared,and the bone reconstruction was not seen.In the 8th week after operation,the experimental sides had the osteogenesis of bone defect part more than 75%,the junction has much more callus formation,boundaries disappeared,medullary cavity was seen.In the12 nd week after operation,the experimental sides bone defect were cured,medullary cavity and bone reconstruction were seen.In this several time points,the situation of the control sides were worse than the experimental sides.Observation of bone density: Bone mineral density is an important symbol of bone quality.The mineral density measurement in bone defect area of the experimental side was done to found that the density was higher than that of the timbering materials at 2nd weeks after operation,and the bone mineral density was getting higher and higher at the 4th,6th,8th weeks after operation,and at the 12 nd weeks the density of the implantation material in experimental sides was similar to the bone materials density of the rabbits.In experimental animal,bone mineral density of the bone defects on the control side was higher than in vitro nanometer stent materials bone mineral density in 4 weeks after surgery.In the following periods of the bone defect bone density values also increased over time,but even in the postoperative 12 nd week,the bone mineral density value in defect area was lower than the experimental animals radial bone mineral density value of itself.Histological results: The osteogenesis was active at the 2nd week after surgery in the experimental sides,experimental sides had local osteoblasts increased,and extracellular matrix began to deposite in a local.Control sides without the active.At the 4th-8th week after surgery,more and more bony callus was formed,and the bone unit began to form and get mature in the experimental sides,the gradual degradation of scaffold materials,osteoclasts on new bone reconstruction,medullary cavity structure appeared gradually.After surgery,at the 12 th week,a large number of mature callus formation and the new bone reconstruction was over,the bone defect cured in clinical.At the 4th week after operation,the control sides had signs of osteogenicity and the callus began to increase from the 6th to 8th weeks after operation.The medullary cavity and mature bony callus could be seen in the 12 th postoperative week.Conclusions1.Using emulsion crosslinking method of preparation of TGF-?1 chitosan sustained release microspheres method was simple and easy.Microspheres had good physical and chemical properties.2.TGF-?1 played an important role in trauma,tissue repair and promoting tissue regeneration.In terms of bone biological effect,TGF-?1 on osteoblast proliferation,differentiation,and microvascular formation and the formation of extracellular matrix had a certain role in promoting.In the application of bone tissue engineering had a broad prospect.3.NHAC/ TGF-?1/chitosan sustained release microspheres was a kind of good bone tissue engineering materials in repairing bone defects.4.NHAC had good biological activity and good bone conduction performance,was also a kind of biodegradable material.Not only could be simply used for bone defect treatment directly,was also a good bone tissue engineering scaffold material. |
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