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.
ObjectiveTo study the effect and feasibility of poly-lactide-co-glycolide (PLGA) loaded with recombinant human bone morphogenetic protein 2 (rhBMP-2) on repairing articular cartilage defect in rabbits. Methods PLGA was made into cylinders which were 4 mm in diameter and 3 mm in thickness. rhBMP-2 was fully homogenated before used. PLGA combined with 0.5 mg rhBMP-2 under the condition of vacuum(700 mmHg),and then lyophilized, packed ,sterilized with ethylene oxide and reserved. Defects of 4 mm in diameter and reaching medullary cavity were made in femoral condyles of 72 two-month-old New Zealand white rabbits. The 36 right defects were repaired with PLGA-rhBMP-2 composites as the experimental group, the 36 left defects with PLGA only as PLGA group, the other 36 left defects were left untreated as control group, and the other 36 right defects with PLGA-MSCs composites as cell group. At 4, 8, 12, 24, 36 and 48 weeks after operation, macroscopical and microscopical observations were made, and the histological grade wasdone.Results After 4 weeks of operation: In the experimental group and cell group, defects were filled with white translucent tissue which appeared smooth and soft; the matrix around chondrocytes was weakly metachromatic, the newly formed cartilage tissue was thicker than normal cartilage tissue; there was no formed tissue in the PLGA group and the blank control group. After 8 weeks of operation: In the experimental group and cell group, the new tissue was white, translucent, tenacious and smooth. The boundary with normal cartilage became vague. New cartilage cells distributed evenly. The cells of the surface layerparalleled, but the deeper layer lost directivity. The matrix dyed weakly. The new cartilage gradually became thinner, but it still thicker than the normal cartilage ones. The PLGA degraded besides some drops.In the blank control group and PLGA group, a little white membrane formed at the bottom of the defect. After 1224 weeks of operation: In the experimental group and cell group, defects were filled with new tissues which were white, translucent, tenacious and smooth. The boundary disappeared.The thickness of the new cartilage was similar to that of the normal ones. The cells of the surface layer paralleled to each other,but the cells of the deeper layer tended to arrange vertically. The matrix around chondrocytes was metachromatic,but the color was lighter than that of the normal cartilage. Bone under the cartilage and the tide mark recovered. The new cartilage linked with nomal cartilage finely.In the blank control group and PLGA group, there was a little fibrous tissue at the bottom of the defect withe obvious boundary. After 36 weeks and 48 weeks of operation：in the experimental group and the cell group, the new cartilage was slightly white，continuous and less smooth. The boundary disappeared. There was no proliferated synovial membrane.The thickenss of the new cartilage was thinner than that of the normal ones. The matrix around chondrocytes was weakly metachromatic. In the blank control group and PLGA group, the defect still existed, but became smaller.At the bottom of the defect, fibrous tissues formed. Some cartilage denudated and became less smooth.Some bone under cartilage exposed,and the synovial membrane became thick. The histologic grade of the repair tissue at 12 weeks and 24 weeks of operation in experimental group and cell group was significantly different from that at 4, 8 and 48 weeks of operation(Plt;0.01). There was also significant difference in the experimental group and cell group compared with the blank control group and PLGA group at each time after operation(Plt;0.01). But there was no significant difference between the experimental group and the cell group. Conclusion In the course of degradation。。。。。。.
ObjectiveTo explore the morphological and functional features of tissue engineered composite constructed with bone mesenchymal stem cells (BMSCs) as seeding cells, thermosensitive collagen hydrogel (TCH) and poly-L-lactic acid (PLLA) as the extracellular matrix (ECM) scaffolds in the dynamic culture system. MethodsBMSCs were separated from long bones of Fischer344 rat, and cultured; and BMSCs at the 3rd generation were seeded on the ECM scaffold constructed with braided PLLA fiber and TCH. The BMSCs-ECM scaffold composite was cultured in the dynamic culture system which was designed by using an oscillating device at a frequency of 0.5 Hz and at swing angle of 70° (experimental group), and in the static culture system (control group) for 7 days. The general observation and scanning electron microscopy (SEM) observation were performed; total DNA content was measured at 0, 1, 3, and 7 days. ResultsPLLA was surrounded by collagen to form translucent gelatiniform in 2 groups; and compact membrane developed on the surface of PLLA. SEM observation showed that BMSCs had high viability and were fusiform in shape with microvilli on the surface of cells, and arranged in line; collagen and cells filled in the pores of PLLA fiber in the experimental group. The cells displayed a flat shape on the surface; there were less cells filling in the pores of PLLA fiber in the control group. At 1, 3, and 7 days, total DNA content in the experimental group was significantly higher than that in control group (P < 0.05). The total DNA content were increased gradually with time in 2 groups, showing significant difference between at 0 day and at 7 days (P < 0.05). ConclusionThe ECM constructed with TCH and PLLA has good biocompatibility. The dynamic cultivation system can promote the cell proliferation, distribution, and alignment on the surface of the composite, so it can be used for tissue engineered composite in vitro.
Objective To review the current researches of scaffold materials for skeletal muscle tissue engineering, to predict the development trend of scaffold materials in skeletal muscle tissue engineering in future. Methods The related l iterature on skeletal muscle tissue engineering, involving categories and properties of scaffold materials, preparative techniqueand biocompatibil ity, was summarized and analyzed. Results Various scaffold materials were used in skeletal muscle tissue engineering, including inorganic biomaterials, biodegradable polymers, natural biomaterial, and biomedical composites. According to different needs of the research, various scaffolds were prepared due to different biomaterials, preparative techniques, and surface modifications. Conclusion The development trend and perspective of skeletal muscle tissue engineering are the use of composite materials, and the preparation of composite scaffolds and surface modification according to the specific functions of scaffolds.
ObjectiveTo summarize the research progress of tissue-engineered bile duct in recent years. MethodsThe related literatures about the tissue-engineered bile duct were reviewed. ResultsIn recent years, the research of tissue-engineered bile duct has made a breakthrough in scaffold materials, seed cells, growth factors etc. However, the tissue-engineered bile duct is still in the research stage of animal experiments, which can not be directly applied to clinical practice. ConclusionsThe research of tissue-engineered bile duct becomes popular at present. With the rapid development of materials science and cell biology, the basic research and clinical application of tissue-engineered duct will be more in-depth research and extension, which might bring new ideas and therapeutic measures for patients with biliary defect or stenosis.
ObjectiveTo explore the feasibility of chitosan/allogeneic bone powder composite porous scaffold as scaffold material of bone tissue engineering in repairing bone defect. MethodsThe composite porous scaffolds were prepared with chitosan and decalcified allogeneic bone powder at a ratio of 1∶5 by vacuum freeze-drying technique. Chitosan scaffold served as control. Ethanol alternative method was used to measure its porosity, and scanning electron microscopy (SEM) to measure pore size. The hole of 3.5 mm in diameter was made on the bilateral femoral condyles of 40 adult Sprague Dawley rats. The composite porous scaffolds and chitosan scaffolds were implanted into the hole of the left femoral condyle (experimental group) and the hole of the right femoral condyle (control group), respectively. At 2, 4, 8, and 12 weeks after implantation, the tissues were harvested for gross observation, histological observation, and immunohistochemical staining. ResultsThe composite porous scaffold prepared by vacuum freeze-drying technique had yellowish color, and brittle and easily broken texture; pore size was mostly 200-300μm; and the porosity was 76.8%±1.1%, showing no significant difference when compared with the porosity of pure chitosan scaffold (78.4%±1.4%) (t=-2.10, P=0.09). The gross observation and histological observation showed that the defect area was filled with new bone with time, and new bone of the experimental group was significantly more than that of the control group. At 4, 8, and 12 weeks after implantation, the bone forming area of the experimental group was significantly larger than that of the control group (P < 0.05). The immunohistochemical staining results showed that osteoprotegerin (OPG) positive expression was found in the experimental group at different time points, and the positive expression level was significantly higher than that in the control group (P < 0.05). ConclusionChitosan/allogeneic bone powder composite porous scaffold has suitable porosity and good osteogenic activity, so it is a good material for repairing bone defect, and its bone forming volume and bone formation rate are better than those of pure chitosan scaffold.
Objective To investigate the application potential of alginate-strontium (Sr) hydrogel as an injectable scaffold material in bone tissue engineering. Methods The alginate-Sr/-calcium (Ca) hydrogel beads were fabricated by adding 2.0wt% alginate sodium to 0.2 mol/L SrCl2/CaCl2 solution dropwise. Microstructure, modulus of compression, swelling rate, and degradability of alginate-Sr/-Ca hydrogels were tested. Bone marrow mesenchymal stem cells (BMSCs) were isolated from femoral bones of rabbits by flushing of marrow cavity. BMSCs at passage 5 were seeded onto the alginate-Sr hydrogel (experimental group) and alginate-Ca hydrogel (control group), and the viability and proliferation of BMSCs in 2 alginate hydrogels were assessed. The osteogenic differentiation of cells embeded in 2 alginate hydrogels was evaluated by alkaline phosphate (ALP) activity, osteoblast specific gene [Osterix (OSX), collagen type I, and Runx2] expression level and calcium deposition by fluorescent quantitative RT-PCR and alizarin red staining, Von Kossa staining. The BMSCs which were embeded in alginate-Ca hydrogel and cultured with common growth medium were harvested as blank control group. Results The micromorphology of alginate-Sr hydrogel was similar to that of the alginate-Ca hydrogel, with homogeneous pore structure; the modulus of compression of alginate-Sr hydrogel and alginate-Ca hydrogel was (186.53 ± 8.37) and (152.14 ± 7.45) kPa respectively, showing significant difference (t=6.853, P=0.002); there was no significant difference (t=0.737, P=0.502) in swelling rate between alginate-Sr hydrogel (14.32% ± 1.53%) and alginate-Ca hydrogel (15.25% ± 1.64%). The degradabilities of 2 alginate hydrogels were good; the degradation rate of alginate-Sr hydrogel was significantly lower than that of alginate-Ca hydrogel on the 20th, 25th, and 30th days (P lt; 0.05). At 1-4 days, the morphology of cells on 2 alginate hydrogels was spherical and then the shape was spindle or stellate. When three-dimensional cultured for 21 days, the DNA content of BMSCs in experimental group [(4.38 ± 0.24) g] was significantly higher than that in control group [(3.25 ± 0.21) g ] (t=8.108, P=0.001). On the 12th day after osteogenic differentiation, the ALP activity in experimental group was (15.28 ± 1.26) U/L, which was significantly higher than that in control group [(12.07 ± 1.12) U/L] (P lt; 0.05). Likewise, the mRNA expressions of OSX, collagen type I, and Runx2 in experimental group were significantly higher than those in control group (P lt; 0.05). On the 21th day after osteogenic differentiation, alizarin red staining and Von Kossa staining showed calcium deposition in 2 groups; the calcium nodules and phosphate deposition in experimental group were significantly higher than those in control group (P lt; 0.05). Conclusion Alginate-Sr hydrogel has good physicochemical properties and can promote the proliferation and osteogenic differentiation of BMSCs, so it is an excellent injectable scaffold material for bone tissue engineering.
Objective To study the mechanism of ectopic osteogenesis of nacre/Polylactic acid (N/P) artificial bone combined with allogenic osteoblasts, and to explore the possibility as a scaffold material of bone tissue engineering. Methods The allogenic- osteoblasts seeded onto N/P artificial bone were co-cultured in vivo 1 week.The N/P artificial bone with allogenic osteoblasts were implanted subcutaneously into the left back sites of the New Zealand white rabbits in the experimental group and the simple N/P artificial bone into the right ones in the control group. The complexes were harvested and examined by gross observation, histologic analysis and immunohistochemical investigation 2, 4 and 8 weeks after implantation respectively.Results In experimental group, the osteoid formed after 4 weeks, and the mature bone tissue withbone medullary cavities formed after 8 weeks; but in control group there was nonew bone formation instead of abundant fibrous tissue after 4 weeks, and more fibrous tissue after 8 weeks.Conclusion N/P artificial bone can be used as an optical scaffold material of bone tissue engineering.
Objective To introduce the materials, preparative technique and endothel ial ization modification of scaffold. Methods The recent original articles about vascular tissue engineering were extensively reviewed and analyzed. Results The materials including natural materials, biodegradable polymers and composite materials were studied in the field of scaffold. The ways of casting, cell self-assembly, gel spinning and electrospinning were appl ied to prepare the scaffold of vascular tissue engineering. The modification of scaffold was one of the most important elements for vascular tissue engineering. Conclusion The recent researchs about scaffold of vascular tissue engineering focus on composite material and electrospinning, the modification of scaffold can improve the abil ity of adhesion to endothel ial cells.
Objective To review the research progress of articular cartilage scaffold materials and look into the future development prospects. Methods Recent literature about articular cartilage scaffold for tissue engineering was reviewed, and the results from experiments and clinical application about natural and synthetic scaffold materials were analyzed. Results The design of articular cartilage scaffold for tissue engineering is vital to articular cartilage defects repair. The ideal scaffold can promote the progress of the cartilage repair, but the scaffold materials still have their limitations. Conclusion It is necessary to pay more attention to the research of the articular cartilage scaffold, which is significant to the repair of cartilage defects in the future.