Objective To observe the repairing effects of bone after nano-hydroxyapatite/collagen (nHAC)being implanted in and to study its prospect in clinical application.Methods Nano-hydroxyapatite/collagen composite was developed by biomimetic method. The material was used in clinical operation,the healing effects of bone defects were assessed by methods of radiography.Results The composite showed some features of natural bone in both composition and microstructure.After implanting,the patients were not hyperpyrexial,did not have extravasate and immunoreaction,the bone defects were healing well.Conclusion The composite can serve as one of the promising materials for bone repairing.

BACKGROUND:Selection of proper bone transplantation materials to substitute autogenous bone for treatment of jaw bone defect in patients has become the focus of current researches.OBJECTIVE:To observe the ability of tissue engineered bone constructed with nano-hydroxyapatite/collagen/poly(L-lactic acid)(nHAC/PLA)co-cultured with bone marrow stromal cells(BMSCs)in treatment of rabbit mandibular defect.and to make a comparison with autogenous bone and simple nHAC/PLA.DESIGN.TIME AND SETTING:A randomized controlled animal experiment was performed at the Animal Laboratory of Jinzhou Central Hospital between March and October 2007.MATERIALS:A total of 40 New Zealand rabbits were randomized to 4 groups.with 10 rabbits per group:nHAC/PLA co-cultured with rabbit BMSCs(BMSCs/nHAC/PLA),autogenous bone,nHAC/PLA,and control.METHODS:A 15 mm×15 mm full-thickness bone defect was created in rabbit mandible body.In the BMSCs/nHAC/PLA group.bone defect was repaired by nHAC/PLA co-cultured with BMSCs for 14 days in vitro;the bone defect in the autogenous bone and nHAC/PLA groups was treated by autogenous iliac bone and nHAC/PLA.respectively;while the control group received no any treatment.MAIN OUTCOME MEASURES:At 1,3,and 6 months after surgery,bone mineral density(BMD)measurement and histological examination were performed to evaluate the repairing effects of bone defect.RESULTS:The BMSCs/nHAC/PLA group exhibited the BMD similar to the autogenous bone group(P＞0.05),but it was significantly higher compared to the nHAC/PLA group and the blank control group(P＜0.01).At 6 months after surgery.newly formed bone tissue grew towards large bulk and bridged defected stumps.and the seaffold materials were hardly seen in the BMSCs/nHAC/PLA and autogenous bone groups;simultaneously.the nHAC/PLA group exhibited increased trabecular bone with many fibrous tissues and incompletely degraded seaffold materials.CONCLUSION:BMSCs/nHAC/PLA seaffold exhibits the effects similar to autogenous bone.but superior to nHAC/PLA seaffold in the treatment of mandibular defects.

BACKGROUND:Titanium implants as a safe biological material have been used to produce the artificial Russian titanium cornea, but complications stil exist, including artificial cornea shift, leakage, corneal tissue melting and artificial cornea discharge.
OBJECTIVE:To evaluate in vivo biocompatibility of hydroxyapatite modified titanium skirt for keratoprosthesis in alkali burn cornea.
METHODS:A total of 30 alkali burned New Zealand white rabbit corneas were divided into three group groups. Hydroxyapatite modified titanium skirt (experimental group) and titanium skirt (control group) were respectively inserted into the corneal stroma of rabbits. In the blank control group, only a lamel ar corneal incision was made.
RESULTS AND CONCLUSION:Al skirts were stable without necrosis, melting and exclusion during the observation period. The number of inflammatory cells in the experimental and control groups was significantly higher than that in the blank control group at 2 and 8 weeks postoperatively (P<0.05), but there was no difference in inflammatory cellinfiltration among different groups by the 16th week. The number of corneal fibroblasts increased significantly in the experimental group compared with the control and blank control group after 2, 8, 16 weeks (P<0.05). The extracellular matrix deposited on the surface of hydroxyapatite modified titanium skirt was denser and tighter than that on the surface of titanium skirt. It indicates that hydroxyapatite modified titanium skirt for keratoprosthesis can promote the interfacial biointegration of skirt and host cornea.

Objective To investigate the preparation of a biodegradable intravascular stent (BIS) with poly-l-lactic acid (PLLA), and to evaluate its physical and mechanical properties, as well as its biocompatibility. Methods The study of this BIS was first prepared by PLLA with molecular weight of 100 000 unit as the strut, and then the micro-porous structure was fabricated and the film was coated at the struts. Following the solidified shaping of BIS, the primary physical and mechanical properties of the BIS were tested, and 22 zigzag type BISs were implanted into the aorta and iliac arteries of 11 canines, then they were euthanized according to a fixed timetable for histopathological assessment. Results Two types of BIS (spiral and zigzag) were prepared, and the strut diameter of the BIS was 0.1-0.6 mm, stent diameter of BIS was 6-15 mm, and stent length was 30-80 mm. Of this BIS, the radial strength was 1.6-2.0 kPa (1 kPa=7.5 mm Hg), the dilatable rate was 6.0-6.5, the shortening rate was smaller than 8%-10%, and the proportion of stent surface area to open surface area was 0.16-0.18 (

Objective To define the effect of drug eluting BIS with antiproliferation agent-paclitaxel in preventing vascular restenosis.Methods Bare BIS and drug BIS with 60 ?g paclitaxel were prepared. Both types of the BIS were implanted into the infrarenal restenosis aortas in canine models, and the animals were euthanized 6 weeks after implantation for histopathological, morphometric and immunohistochemical assessment.Results The mean lumen area of bare BIS group was (77 586.5?66.0) ?m2, and lumen of paclitaxel eluting BIS group was (113 435.9?71.0) ?m2. The mean neointima area of bare BIS group was (24 803?56) ?m2, and paclitaxel eluting BIS group was (12 931?63) ?m2. The PCNA-positive ratio was (38?15)% in bare BIS group and (11?0.31)% in paclitaxel eluting BIS group. The statistically significant difference between the two groups were noted ( P

Objective:To study the feasibility of a new composite mineralized collagen membrane in alveolar ridge preservation.Methods:The third mandibular premolars on both sides were extracted from 12 dogs,the 24 alveolar sockets were randomly assigned into A,B and C groups(n =8).The distal alveolar sockets of group A was immediately implanted with the new composite mineralized collagen membrane and bone graft material,those of group B with bone graft material,group C was the blank control.The healing of sockets was evaluated by gross observation,morphological measurements,X-ray microscope and photographs of spiral CT.Results:The horizontal width of the alveolar process of group A was bigger than that of group B (P ＜ 0.05),that of group B was bigger than that of group C (P ＜ 0.05).The region of extraction interest in spiral CT value was higher in group A than that in group B and C (P ＜ 0.05).The extraction sockets were generated new bone and the degree of reconstruction measurements was higher in group A than that in group B and C (P ＜ 0.05).Conclusion:The new composite mineralized collagen membrane can induce the regeneration of new bone,and preserve the alveolar.

Objective To explore the possibility of repairing injured facial nerve with tissue engineering technology and neural stem cells(NSCs).The complex consisted of NSCs,scaffold and NT-3.NSCs were immature cells with the potential of self-renewal and multiple differentiation to neurons and glial cells.The scaffold with porous surface was made of hyaluronic acid and collagen(HA-Col gel) which degenerate in vivo after transplantation.NT-3 is the signal to promote neurons survival in vitro.Methods NSCs of S-D rat were co-cultured with scaffold and NT-3 in vitro.The two stumps of disconnected facial nerve of rabbit were re-connected with the complex.Electrophysiology and morphology tests were used to examine functional and morphological changes.Results Result] NSCs adhered to the HA-Col gel and survived.Injured facial nerve fixed by NSCs-HA-Col gel-NT-3 complex showed significant improvement in function and anatomical structure.Conclusion Combinative implant of NSCs,HA-Col gel and NT-3 may promote the regeneration of injured facial nerve.

ObjectiveTo evaluate the effectiveness of mesenchymal stem cell (MSC) in osteonecrosis of the femoral head defect(ONFH) repair. MethodsAniaml model of ONFH defect were established with rabbits, which were divided into 3 groups,group A did not infill anything as control, nano Hydroxyapatite/collagen(nHAC) as group B,nHAC+MSC as group C.Histology change were investigated 4,8,12 weeks after operation respectively.Results groups B and C were different with group A. The difference between groups A and C was more significant. ConclusionMesenchymal stem cell has a strong activity of osteoconduction,it has a value in repairing the bone defect of ONFH and the treatment of ONFH.

Biodegradable magnesium-alloy stents have been employed in animal experiments and clinical researches in recent years. Magnesium-alloy stents have been reported to be biocompatible, and degradable due to corrosion after being implanted into blood vessel. However, magnesium alloy is brittle compared with stainless steel. This may cause strut break under large deformation. In this paper, a finite element model of magnesium-alloy stent was set up, with reference to pictures from Biotronik Corporation, to simulate the expanding and bending processes. The results of analysis show that the maximum strain during expanding reaches 20%, being greater than the elongation limit of the commercially available magnesium alloys. Therefore, to avoid strut breakage during expanding, the magnesium alloys should be custom-made. The plasticity of the material should be improved by grain refinement processes before practicable magnesium-alloy stents could be developed.
Absorbable Implants ; Alloys ; Angioplasty, Balloon, Coronary ; instrumentation ; Finite Element Analysis ; Humans ; Magnesium ; Materials Testing ; Prosthesis Design ; Stents ; Stress, Mechanical ; Surface Properties