OBJECTIVE: From the point of view of material science, the methods of tissue repair and defect reconstruct were discussed, including mesenchymal stem cells (MSCs), growth factors, gene therapy and tissue engineered tissue. METHODS: The advances in tissue engineering technologies were introduced based on the recent literature. RESULTS: Tissue engineering should solve the design and preparation of molecular scaffold, tissue vascularization and dynamic culture of cell on the scaffolds in vitro. CONCLUSION: Biomaterials play an important role in the tissue engineering. They can be used as the matrices of MSCs, the delivery carrier of growth factor, the culture scaffold of cell in bioreactors and delivery carrier of gene encoding growth factors.
Objective To study the potential of a bioderived material combined with Pluronic F-127 in vitro as a delivery vehicle for WO-1 in the bone repair therapy. Methods Bio-derived materials were fabricated and loaded with WO-1 by Pluronic F-127. Micromorphology and porosity were detected by the scanning electron microscope and the digital image analysis system respectively. The WO-1 release from the system in vitro was studied by the high performance liquid chromatography. Results Bio-derived material-WO-1 drug delivery systems were created with the interconnected pore network. Theporosity and pore size of the system were 55% and 522.43±16.75 μm respectively, compared with those of bio-derived materials, which were 75% and 623.67±12.31 μm respectively. And the main composition of the system was HA. The in vitrorelease kinetics of WO-1 revealedthat an effective therapeutic concentration(0.2-0.8 μg/ml) of WO-1 was maintained for 6 days after a high initial burst release. Conclusion The bio-derived material-WO-1 drug delivery system can be used in the bone repair therapy. However, the in vivostudy on it is still needed.
Objective To illustrate the effect and complication of orthopedic applications for biodegradable and absorbable internal fixation of fractures, and to indicate the existent problem and research aspect currently. Methods The recent literatures on orthopedic applications and study of biodegradable and absorbable internal fixation for fractures were reviewed. The effect of biodegradable materials on bone healing was summarized. Results It is good for the stability of fracture fixation and result of treeatment. The biodegradable and absorbable internal fixation fractures had no adverse effect on bone healing. Conclusion There will be more widespread application for biodegradable and absorbable materials in orthopedics, but the intensive research should be carried out to prevent its complication.
OBJECTIVE: To construct tissue engineering bone with bio-derived materials and bone marrow stromal cells (MSCs), and to investigate the effect of allogeneic engineering bone implants on healing of segmental bone defects. METHODS: MSCs being aspirated aseptically from tibial tuberosities of young rhesus monkeys were induced into osteoblasts in vitro and then were cultured and marked with 5-bromo-2-deoxyuridine (BrdU). Tissue engineering bones were constructed with these labeled osteoblasts being seeded onto bio-derived materials made from fresh human bones which were treated physically and chemically, Then the constructs were implanted in 15 allogeneic monkeys to bridge 2.5 cm segmental bone defects of left radius as experimental groups, bio-derived materials only were implanted to bridge same size defects of right radius as control group. and, 2.5 cm segmental bone defects of both sides of radius were left empty in two rhesus monkeys as blank group. Every 3 monkeys were sacrificed in the 1st, 2nd, 3rd, 6th and 12th weeks postoperatively and both sides of the implants samples were examined macroscopically, histologicaly, and immunohistochemicaly. The two monkeys in blank group were sacrificed in the 12th week postoperatively. RESULTS: Apparent inflammatory reactions were seen around both sides of the implants samples in the 1st, 2nd, 3rd weeks, but it weakened in the 6th week and disappeared at the 12th week. The labeled osteoblasts existed at the 6th week but disappeared at the 12th week. The bone defects in experimental group were repaired and the new bone formed in multipoint way, and osteoid tissue, cartilage, woven bone and lamellar bone occurred earlier when compared with control group in which the bone defects were repaired in ’creep substitution’ way. The bone defects in blank group remained same size at the 12th week. CONCLUSIONS: Engineering bones constructed with bio-derived materials and MSCs were capable of repairing segmental bone defects in allogeneic monkeys beyond ’creep substitution’ way and making it healed earlier. Bio-derived materials being constituted with allogeneic MSCs may be a good option in construction of bone tissue engineering.
Objective To explore the method of preparing the electrospinning of synthesized triblock copolymers of ε-caprolactone and L-lactide (PCLA) for the biodegradable vascular tissue engineering scaffold and to investigateits biocompatibil ity in vitro. Methods The biodegradable vascular tissue engineering scaffold was made by the electrospinning process of PCLA. A series of biocompatibil ity tests were performed. Cytotoxicity test: the L929 cells were cultured in 96-wellflat-bottomed plates with extraction media of PCLA in the experimental group and with the complete DMEM in control group, and MTT method was used to detect absorbance (A) value (570 nm) every day after culture. Acute general toxicity test: the extraction media and sal ine were injected into the mice’s abdominal cavity of experimental and control groups, respectively, and the toxicity effects on the mice were observed within 72 hours. Hemolysis test: anticoagulated blood of rabbit was added into the extracting solution, sal ine, and distilled water in 3 groups, and MTT method was used to detect A value in 3 groups. Cell attachment test: the L929 cells were seeded on the PCLA material and scanning electron microscope (SEM) observation was performed 4 hours and 3 days after culture. Subcutaneous implantation test: the PCLA material was implanted subcutaneously in rats and the histology observation was performed at 1 and 8 weeks. Results Scaffolds had the characteristics of white color, uniform texture, good elasticity, and tenacity. The SEM showed that the PCLA ultrafine fibers had a smooth surface and proper porosity; the fiber diameter was 1-5 μm and the pore diameter was in the range of 10-30 μm. MTT detection suggested that there was no significant difference in A value among 3 groups every day after culturing (P gt; 0.05). The mice in 2 groups were in good physical condition and had no respiratory depression, paralysis, convulsion, and death. The hemolysis rate was 1.18% and was lower than the normal level (5%). The SEM showed a large number of attached L929 cells were visible on the surface of the PCLA material at 4 hours after implantation and the cells grew well after 3 days. The PCLA material was infiltrated by the inflammatory cells after 1 week. The inflammatory cells reduced significantly and the fiber began abruption after 8 weeks. Conclusion The biodegradable vascular tissue engineering scaffold material made by the electrospinning process of PCLA has good microstructure without cytotoxicity and has good biocompatibil ity. It can be used as an ideal scaffold for vascular tissue engineering.
To develop the chitosan /polyethylene glycols succinate (CH/PEG-SA) mitomycin C (MMC) film drug del ivery system and its release effect in vitro. Methods MMC loading in composite films was determined using a UV-visible spectrophotometer. Freeze-dried films (90 mg) were immersed in 1 mL PBS buffer (pH 7.4). The concentrations ofMMC releasing in vitro were calculated refer to the standard curve of relationship between the concentrations of MMC and the value of UV-visible spectrophotometer. The curve of the concentrations of MMC releasing from the films in vitro was drawn at different time. The relationship between the films, structure and the drug releasing was revealed. Results The films showed swell ing without brittleness. The equation of Linear Regression was y=0.593x3– 2.563x2 +25.944x – 0.236 (R2=1.000). The film had a good drug del ivery capabil ity. The samples weighing 20 mg were soaked into the l iquid of PBS, the releasing concentrations of MMC were 14.961 6 μg/mL at 12 days, 14.482 4 μg/mL at 18 days and 11.409 2 μg/mL at 32 days, which was higher than ID50 of MMC (10.471 3 μg/L) to fibroblast. Then MMC was released at a low concentration. The releasing concentrations of MMC was 0.179 3 μg/ mL at 60 days until being del ivered completely. Conclusion The flexibil ity is enhanced , and the mechanical function is improved, so that there is better nature of membrane. The initial burst is avoided more effectively, and the drug releasing would be maintained for a certain time.
Objective To investigate the latest development of tissue engineeredregenerative medicine in industrialization, with the intention to direct work in practical area. Methods A complete insight of regenerative medicine in industrialization was obtained through referring to update publications, visiting related websites, as well as learning from practical experience. Results The aerial view of the future of regenerative medicine was got based on knowledge of four different tissue engineering projects. Conclusion All present efforts should be devoted to regenerative medicine area meeting the industrialized trends.
Objective To introduce the research advances of scaffold materials of intervertebral disc tissue engineering. Methods The recent original articlesabout the scaffolds in intervertebral disc tissue engineering were extensively reviewed. Results At present, agarose, alginate gel, collagentype Ⅰ, PLA, PGAare still major scaffold materials for intervertebral disc tissue engineering because of their good biocompatibility. Conclusion It is one of the popular studies on current intervertebral disc tissue engineering to explore the ideal scaffold materials.
OBJECTIVE: To investigate the selection and manufacture of ideal extracellular matrix materials in bone tissue engineering. METHODS: The recent literatures about biodegradable polymers served as culture scaffolds of osteoblasts were widely reviewed, the advantages and disadvantages of biodegradable synthetic polymers and natural polymers were analysed. RESULTS: The ideal extracellular matrix material in bone tissue engineering should be made up of inorganic materials, synthetic polymers and natural polymers, which possesses morphological structure of three-dimensional foam with self-mediated drug slow delivery system of bone growth factors. CONCLUSION: The design and manufacture of combined extracellular matrix materials in bone tissue engineering is a very important and urgent challenge.
OBJECTIVE: To study the feasibility of calcium polyphosphate fiber (CPPF) as the scaffold material of tendon tissue engineering. METHODS: CPPF (15 microns in diameter) were woven to form pigtail of 3 mm x 2 mm transverse area; and the tensile strength, porous ratio and permeability ratio were evaluated in vitro. Tendon cells (5 x 10(4)/ml) derived from phalangeal flexor tendon of SD rats were co-culture with CPPF scaffold or CPPF scaffold resurfaced with collagen type-I within 1 week. The co-cultured specimens were examined under optical and electric scanning microscope. RESULTS: The tensile strength of CPPF scaffolds was (122.80 +/- 17.34) N; permeability ratio was 61.56% +/- 14.57%; and porous ratio was 50.29% +/- 8.16%. CPPF had no obvious adhesive interaction with tendon cells, while CPPF of surface modified with collagen type-I showed good adhesive interaction with tendon cells. CONCLUSION: The above results show that CPPF has some good physical characteristics as scaffold of tendon tissue engineering, but its surface should be modified with organic substance or even bioactive factors.