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 summarize the research progress of several three-dimensional (3-D) printing scaffold materials in bone tissue engineering. MethodThe recent domestic and international articles about 3-D printing scaffold materials were reviewed and summarized. ResultsCompared with conventional manufacturing methods, 3-D printing has distinctive advantages, such as enhancing the controllability of the structure and increasing the productivity. In addition to the traditional metal and ceramic scaffolds, 3-D printing scaffolds carrying seeding cells and tissue factors as well as scaffolds filling particular drugs for special need have been paid more and more attention. ConclusionsThe development of 3-D printing porous scaffolds have revealed new perspectives in bone repairing. But it is still at the initial stage, more basic and clinical researches are still needed.
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.
ObjectiveTo review the research progress of tissue engineered ligament. MethodsThe literature in recent years on tissue engineered ligament in repair of anterior cruciate ligament (ACL) injury was extensively reviewed, including cell sources, scaffold materials, growth factors, and mechanical stimulation in tissue engineered ligament. ResultsTissue engineered ligament constructed by mesenchymal stem cells and ACL fibroblasts has been successfully used in animal experiments. It is crucial for qualified tissue engineered ligament to choose appropriate seed cells, scaffold, mechanical stimulation, and essential cytokines. To further optimize culture condition and how to realize the tissue engineered ligament in vivo better survival and prognosis need to be further studied. ConclusionEnormous progress has been made in tissue engineered ligament for repair and regeneration of ACL. With the development of biochemistry and scaffold materials, tissue engineered ligament will be used in clinic in the near future.
【Abstract】 Objective To compare the effect of PLGA and collagen sponge combined with rhBMP-2 on repairing ofarticular cartilage defect in rabbits respectively. Methods PLGA and collagen sponge were made into cyl inders which were 4 mm in diameter and 3 mm in thickness, and compounded with rhBMP-2 (0.5 mg). Defect 4 mm in diameter were made in both of femoral condyles of 24 two-month-old New Zealand white rabbits. The defects in right 18 knees were treated with PLGA/rhBMP-2 composites (experimental group 1), and the left 18 knees were treated with collagen sponge/rhBMP-2 composites (experimental group 2), the other 12 knees were left untreated as control group. At 4, 12 and 24 weeks after operation, the animals were sacrificed and the newly formed tissues were observed macroscopically and microscopically, graded histologically and analyzed statistically. Results From the results of macroscopical and microscopical observation, in the experimental group 1, the defects were filled with smooth and translucent cartilage; while in the experimental group 2, the white translucent tissues did notfill the defects completely; and in the two experimental groups, the new cartilage tissues demarcated from the surrounding cartilage,chondrocytes distributed uniformly but without direction; a l ittle fibrous tissue formed in the control group 4 weeks postoperatively. In the experimental group 1, the defects were filled completely with white, smooth and translucent cartilage tissue without clear l imit with normal cartilage; while in the experimental group 2, white translucent tissues formed, the boundary still could be recognized; in the two experimental groups, the thickness was similar to that of the normal cartilage; the cells paralleled to articular surface in the surface layer, but in the deep layer, the cells distributed confusedly, the staining of matrix was positive but a l ittle weak; subchondral bone and tide mark recovered and the new tissue finely incorporated with normal cartilage;however, in the control group, there was a l ittle of discontinuous fibrous tissue, chondrocytes maldistributed in the border andthe bottom of the defects 12 weeks postoperatively. In the experimental group 1, white translucent cartilage tissues formed, the boundary disappeared; in the experimental group 2, the color and the qual ity of new cartilage were similar to those of 12 weeks; in the two experimental groups, the thickness of the new cartilage, which appeared smooth, was similar to that of the normal cartilage, the chondrocytes arranged uniformly but confusedly; the staining of matrix was positive and subchondral bone and tide mark recovered, the new tissue finely incorporated with normal cartilage; in the control group, a layer of discontinuous fibrous tissue formed in the bottom of the defects 24 weeks postoperatively. Results of histological grade showed that there were significantdifference between experimental group (1 and 2) and control group at any time point (P lt; 0.01); the scores of 12 weeks and 24 weeks in experimental group 1 and 2 had a significant difference compared with that of 4 weeks (P lt; 0.01), there was no significant difference between 12 weeks and 24 weeks (P gt; 0.05), and there were no significant difference between the two experimental groups at the same time point (P gt; 0.05). Conclusion Both PLGA and collagen sponge as a carrier compounded with rhBMP-2 can repair articular cartilage defects.
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.
ObjectiveTo study the preparation method of acellular dermal matrix (ADM) for cartilage tissue engineering and analyze its biocompatibility. MethodsThe dermal tissues of the calf back were harvested, and decelluarized with 0.5% SDS, and the ADM was reconstructed with 0.5% trypsin, cross-linked with formaldehyde, and modified with 0.5% chondroitin sulfate which can promote the proliferation of chondrocytes. And the porosity, cytotoxicity, and biocompatibility were determined. Co-cultured 2nd passage chondrocytes and bone marrow stromal cells in a proportion of 3 to 7 were used as seed cells. The cells were seeded on ADM (experimental group) for 48 hours to observe the cell adhesion. The expressions of mRNA and protein of collagen type Ⅱ were tested by RT-PCR and Western blot methods, respectively. And the expressions were compared between the cells seeded on the scaffold and cultured in monolayer (control group). ResultsAfter modification of 0.5% trypsin, the surface of ADM was smooth and had uniform pores; the porosity (85.4%±2.8%) was significantly higher than that without modification (72.8%±5.8%) (t=-4.384, P=0.005). The cell toxicity was grade 1, which accords to the requirements for cartilage tissue engineering scaffolds. With time passing, the number of inflammatory cells decreased after implanted in the back of the rats (P<0.05). The scanning electron microscope observation showed that lots of seed cells adhered to the scaffold, the cells were well stacked, displaying surface microvilli and secretion. The expressions of mRNA and protein of collagen type Ⅱ were not significantly different between experimental and control groups (t=1.265, P=0.235;t=0.935, P=0.372). ConclusionThe ADM prepared by acellular treatment, reconstruction, cross-linking, and modification shows perfect characters. And the seed cells maintain chondrogenic phenotype on the scaffold. So it is a proper choice for cartilage tissue engineering.
ObjectiveTo observe the bladder regeneration by collagen membrane scaffolds for bladder construction to find a new alternative scaffold material. MethodsTwelve healthy adult male Sprague Dawley rats, weighing 300-350 g, were randomly divided into collagen membrane scaffold group (experimental group, n=6), and sham operated group (control group, n=6). Upper hemicystectomy was performed and collagen scaffold was used for reconstruction in experimental group, while the bladder was turned over without bladder resection in control group. At 30 days after operation, the animals were sacrificed and grafts were harvested;HE staining and Masson staining were used to evaluate the bladder regeneration, immunohistochemical staining was performed with α-smooth muscleactin (α-SMA) and von Willebrand factor (vWF) markers to evaluate the percentage of α-SMA positive area and capillary number. ResultsThe rats of 2 groups survived to the end of the experiment, and no urine leakage or infection was observed in experimental group. Histologically, control group presented a pattern of normal bladder structure, experimental group presented a pattern of almost normal urothelium with a small amount of smooth muscle cells and a thin layer of undegraded collagen fibers. Immunohistochemically, experimental group showed ingrowth of smooth muscle fibers and new capillary formation along the collagen membrane scaffolds. The percentage of α-SMA positive area and capillary number in experimental group were significantly lower than those in control group (6.49%±2.14% vs. 52.42%±1.78% and 4.83±0.75 vs. 14.83±1.17, respectively)(t=40.40, P=0.00; t=17.62, P=0.00). ConclusionThe collagen membrane scaffolds could be an effective scaffold material for bladder reconstruction.
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 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.