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BACKGROUND:The bioceramics has the ideal pore size, high porosity and the through-hole rate, can provide the ideal physiological activity space for the bone cel repair, and can obviously improve bone conduction. OBJECTIVE:To explore the bone conduction and bone induction in the repair of bone defects in the stage of bone defect of bionic biphasic ceramic bioactive bone. METHODS:A total of 20 New Zealand white rabbits were randomly divided into bioactive glass and biomimetic biphasic ceramic bioactive bone groups, and were used to construct the animal bone damage model. They were given the repair with bioactive glass and biomimetic biphasic ceramic bioactive bone. RESULTS AND CONCLUSION:At 4 weeks after model establishment, scanning electron microscopy demonstrated that dense periosteal tissue was observed in the biomimetic biphasic ceramic bioactive bone group. At 8 weeks, dense combination was found, and no obvious fissure existed. At 12 weeks, complete bone demarcation blurred, showing a natural transition. Moreover, the binding site was very dense. There were a large number of new bone tissues, bone trabecula was regular and connected to a piece. The bone material has been largely degraded. Bone defects were repaired completely. The bone density was close to normal bone. At 8 weeks, in the bioactive glass group, the binding site presented obvious fissure. At 12 weeks, the fissure had been connected, but the binding was not tight as compared with the bionic biphasic ceramic biologic active bone group. The bone defect got preliminary repair. A smal number of new bone formed trabecular bone, but could not connect or traverse. There was no recanalization of the marrow cavity. A few continuous bone cal us traversed the broken end. These data demonstrate that bionic biphasic ceramic bioactive bone has good bone conduction, bone induction and biocompatibility in the repair of segmental bone defects.
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BACKGROUND:Degradable polymer materials initiate the degradation process immediately after implantation. How to regulate the degradation of these materials is rarely reported at present. OBJECTIVE:To study the effect of ultrasonic wave on control ing the degradation of polymer materials. METHODS:The sample is made ofε-caprolactone/L-lactide copolymer, and its core was coated with low density polyethylene on the surface with the fol owing four different methods. (1) The core surface was firstly covered with CaCl 2 powder, and then coated with polyethylene. (2) The core was firstly coated with polyethylene and coarsened for 3 hours. (3) The core surface was firstly covered with CaCl 2 powder, and then coated with polyethylene, and coarsened for 3 hours. (4) The core was directly coated with polyethylene. The four kinds of specimens obtained were embedded in pork for ultrasonic bombardment experiment in vitro. RESULTS AND CONCLUSION:In the specimens prepared with methods 1 and 4, the lyophobic layer could protect core materials before ultrasonic treatment, and no absorption peak was found at 631 nm. After ultrasonic treatment, the lyophobic layer was destroyed, toluidine blue dye was released, leading to change the color of immersion solution and increase the absorption peak at 631 nm. In the specimens prepared with methods 2 and 3,the lyophobic layer cannot exhibit the protection effects, the absorption peak was found at 631 nm. Under electron microscope, the appearance of the specimens in four groups was changed obviously. It is feasible to control the starting of the degradation by coating the degradable copolymer with LDPE and using ultrasonic as a trigger.
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BACKGROUND:With the social and economic development and aging, coronary heart disease has become the primary cause of death endangering human life and health, while cardiovascular intervention (especial y stenting) in the treatment of cardiovascular disease is at a growing status. OBJECTIVE:To describe the development, research progress and latest clinical application of heart interventional materials as wel as advantages and disadvantages of biodegradable stents, and meanwhile to prospect for its future development and improvement. METHODS:A computer-based online search was conducted in PubMed for English language publications from January 1999 to April 2014 using the key words of“stent, scaffold, bioabsorbable, bioresorbable, biodegradable, biocompatibility, material properties”in English. RESULTS AND CONCLUSION:The new ful y biodegradable stents are considered as another major progress in the cardiac intervention, which brings a new gospel for patients with coronary heart disease. In the initial stage of implantation, biodegradable stents exhibit the same mechanical support as bare metal stents;after implantation, anti-proliferative drugs are released to prevent thrombosis and restenosis, and the stent is completely degraded within a specified period, which significantly reduces the late-stage and very late-stage thrombosis and the risk of in-stent restenosis. However, long-term safety and efficacy of biodegradable stents need further studies. Innovation of stent design and materials science is the key to overcome the current shortcomings of biodegradable stents.
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BACKGROUND:Cross-linking is a common method for the modification of bone tissue engineering materials, but there are few studies about the effect of cross-linking on properties of drug-loaded artificial bone. OBJECTIVE:To study the effect of glutaraldehyde cross-linking on mechanical strength, degradation rate and in vitro release behavior of chitosan/hydroxyapatite-gentamicin delayed materials. METHODS:The chitosan/hydroxyapatite-gentamicin drug-loaded artificial bone and the cross-linked chitosan/hydroxyapatite-gentamicin drug-loaded artificial bone were prepared at 10%, 20%and 30%chitosan mass ratio. The mechanical strength, absorption rate, degradation rate and in vitro release behavior of materials in each group were determined. RESULTS AND CONCLUSION:The compressive strength of 10%, 20%, 30%chitosan/hydroxyapatite-gentamicin drug-loaded artificial bone was (10.16±1.17) MPa, (28.4±0.64) MPa and (23.28±1.30) MPa, respectively. After cross-linking, the strength was increased to (36.3±1.20) MPa, (51.6±2.08) MPa and (36.9±3.22) MPa, respectively. The absorption rate and degeneration rate were reduced by cross-linking. In the first day of drug release in vitro, the rate of gentamicin released from non-cross-linked 30%chitosan/hydroxyapatite-gentamicin drug-loaded artificial bone was 42.2%, while the rate was decreased to 33.6%after cross-linking. At the fol owing 9 days, the total release of the cross-linked material was lower than that of non-cross-linked material. Glutaraldehyde cross-linking could improve the stability, reduce the degradation rate, and significantly ameliorate the release of artificial bone.
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BACKGROUND:The principle of lyophilization is to sublimate the solvent of frozen materials in vacuum and retain the solute, thus making a pore structure. OBJECTIVE: To produce a chitosan tubular scaffold by lyophilization, and to test its physicochemical properties. METHODS: The chitosan tubular material was prepared by lyophilization method, folowed by gross observation and electron microscopic observation. The chitosan tubular material samples were placed into PBS solution and pure water for 50 days, respectively, and then immersed in trypsin liquid for 1 day folowed by embedded into the muscle and dorsal skin of neonatal Sprague-Dawley rats for 30 days. The degradation rate and porosity of the material were observed and calculated. The breaking strength and compressive strength of the material were determined both under drying and soaking conditions using tensile instrument and pressure meter, respectively. RESULTS AND CONCLUSION:The external form of the chitosan tubular material was normaly tubular. Under the electron microscope, it was composited by different size pores, and the pore size was 50-200μm. The degradation rates of the material were (5.33±0.12)% in PBS, (11.26±0.15) in water, 0.012% in the trypsin liquid and (35.2±3.7)in vivo. The porosity rate was (97.5±1.5)%. The breaking strength and compressive strength of the material was higher under the drying state than under the soaking state (P < 0.05). These findings indicate that the lyophilization method can produce the chitosan tubular material with good porosity rate and degradation rate as wel as good tensile ability and compressive capability.
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BACKGROUND:Using degradable materials for bone tissue engineering to treat bone defects is the best choice at present. How to ensure adequate vascularization in materials in order to meet the need of blood supply and an exchange of nutrients for seed cells in the process of bone regeneration is becoming a critical problem reversed from basic research to clinical application. OBJECTIVE:To review the biodegradable materials for bone tissue engineering and the ways to promote vascularization in materials. METHODS:A computer-based search of PubMed and PMC databases was performed by the first author for the literature about biodegradable materials for bone tissue engineering and their vascularization published from 1993 to 2013. The key words were“degradable materials, bone tissue engineering, angiogenesis, vasculogenesis, osteogenesis”in English. RESULTS AND CONCLUSION:The commonly used biodegradable materials for bone tissue engineering include synthetic polymer materials, magnesium al oy, bioactive glass ceramics, calcium phosphate ceramics and composites. We can promote the vascularization of tissue-engineered bone by the fol owing aspects:scaffold fabrication, growth factors, the application of endothelial progenitor cells, cells co-culture and microsurgical techniques. Although the research on the vascularization of tissue-engineered bone has made a great progress, there is stil a lot of shortcomings. We believe that, with the development of mechanism of angiogenesis, the vascularized tissue-engineered bone wil have a promising prospect because of improving the structure and properties of materials, promoting the ability of release-control ed growth factors and their synergies, optimizing the selection and mixed culture of seed cells and improving the microsurgical techniques.
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BACKGROUND:Col agen suture is made of col agen from animals, and has been widely used because it is absorbable, non-rejection and easy to produce, and convenient in use. OBJECTIVE:To evaluate the effects of col agen suture and silk suture in wound healing after oral implant surgery. METHODS:100 patients undergoing oral implantation were randomly assigned into col agen suture group and silk suture group. A 2-0 circular needle with absorbable col agen sutures and a 4-0 circular needle with non-absorbable silk sutures were employed for tension-free suture in the two groups. After 3, 5, 7 days of oral implantation, suture threads and wound healing were observed. The suture was removed at 14 days, and patients were reviewed at 14 days. RESULTS AND CONCLUSION:The wound healing was better in the col agen suture group than the silk suture group at grade I (P<0.05). At 7 days postoperatively, the suture thread was mostly absorbed in the col agen group but not in the silk suture group. In addition, material alba was invisible in the col agen suture group but clear in the silk suture group. These results indicate that the col agen suture is more proper for tension-free suture than the silk suture, which is better matched to the healing time and keeps a better oral environment.