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.
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.
Objective To review the research status of the neovascularization of adi pose tissue engineering in the past decade so as to provide theoretical references for the development of the rapid revascularization of tissue engineered adi pose. Methods The l iterature about the revascularization of adi pose tissue engineering was extensively reviewed andanalyzed, centering on 5 elements: specificity of histological structures and blood supply, revascularization mechanism, coculture of different seed cells, modification of scaffold, and microenvironment. Results Adi pose tissue engineering offers a new solution for soft tissue defects. However, there is still the unfulfilled need in the size of engineered adipose tissue (less than 1 mL), which was determined by the degree of neovascularization in engineered tissue. Overall, rapid neovascularization in engineering tissue is a key l ink of experimental study changing into cl inical appl ication. Conclusion Providing a sufficient supply with nutrients and oxygen by means of a sufficient and rapid neovascularization will be at the heart of any attempts to obtain bigger tissue engineered adipose to meet the demand of repairing large soft tissue defect.
Objective To review the current research status and clinical application progress of extracellular matrix (ECM) material in tissue engineering. Methods The literature about the latest progress in the preparation, biocompatibility, mechanical property, degradability, and clinical application of ECM material was extensively reviewed. Results The improvement of the ECM preparation method and thorough understanding of the immunological properties have laid the foundation for the repair and reconstruction of the tissue. Moreover, a series of animal studies also confirm that the feasibility and effectiveness of the ECM such as small intestinal submucosa, bladder ECM grift, and acellular dermis which have been applied to the repair and reconstruction of the urethra, bladder, arteries, and skin tissue. It shows a wide prospect of clinical application in the future. Conclusion ECM material is a good bio-derived scaffold, which is expected to become an important source of alternative materials for the repair and reconstruction of the tissue.
ObjectiveTo review the research progress of the tissue engineering technique in the esophageal defect repair and reconstruction. MethodsThe recently published clinical and experimental literature at home and abroad on the scaffold materials and the seeding cells used in the tissue engineered esophageal reconstruction was consulted and summarized. ResultsA large number of basic researches and clinical applications show that the effect of the tissue engineered esophagus is close to the autologous structure and function of the esophagus and it could be used for the repair of the esophageal defect. However, those techniques have a long distance from the clinical application and need an acknowledged rule of technology. ConclusionTissue engineering technique could provide an innovative theory for the esophageal defect reconstruction, but its clinical application need further research.
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 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 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 study the preparation and cytocompatibility of bone tissue engineering scaffolds by combining low temperature three dimensional (3D) printing and vacuum freeze-drying techniques. MethodsCollagen (COL)and silk fibroin (SF) were manufactured from fresh bovine tendon and silkworm silk. SolidWorks2014 was adopted to design bone tissue engineering scaffold models with the size of 9 mm×9 mm×3 mm and pore diameter of 500μm. According to the behavior of composite materials that low temperature 3D printing equipment required, COL, SF, and nano-hydroxyapatite (nHA)at a ratio of 9:3:2 and low temperature 3D printing in combination with vacuum freeze-drying techniques were accepted to build COL/SF/nHA composite scaffolds. Gross observation and scanning electron microscope (SEM) were applied to observe the morphology and surface structures of composite scaffolds. Meanwhile, compression displacement, compression stress, and elasticity modulus were measured by mechanics machine to analyze mechanical properties of composite scaffolds. The growth and proliferation of MC3T3-E1 cells were evaluated using SEM, inverted microscope, and MTT assay after cultured for 1, 7, 14, and 21 days on the composite scaffolds. The RT-PCR and Western blot techniques were adopted to detect the gene and protein expressions of COL I, alkaline phosphatase (ALP), and osteocalcin (OCN) in MC3T3-E1 cells after 21 days. ResultsCOL/SF/nHA composite scaffolds were successfully prepared by low temperature 3D printing technology and vacuum freeze-drying techniques; the SEM results showed that the bionic bone scaffolds were 3D polyporous structures with macropores and micropores. The mechanical performance showed that the elasticity modulus was (344.783 07±40.728 55) kPa; compression displacement was (0.958 41±0.000 84) mm; and compression stress was (0.062 15±0.007 15) MPa. The results of inverted microscope, SEM, and MTT method showed that a large number of cells adhered to the surface with full extension and good cells growth inside the macropores, which demonstrated a satisfactory proliferation rate of the MC3T3-E1 cells on the composite scaffolds. The RT-PCR and Western blot electrophoresis revealed gene expressions and protein synthesis of COL I, ALP, and OCN in MC3T3-E1 cells. ConclusionLow temperature 3D printing in combination with vacuum freeze-drying techniques could realize multi-aperture coexisted bionic bone tissue engineering scaffolds and control the microstructures of composite scaffolds precisely that possess good cytocompatibility. It was expected to be a bone defect repair material, which lays a foundation for further research of bone defect.
ObjectiveTo prepare the aortic extracellular matrix (ECM) scaffold by using different methods to decellularize porcine ascending aorta and to comprehensively compare the efficiency of decellularization and the damage of ECM, evaluation of biomechanical property and biocompatibil ity. MethodsThirty specimens of fresh porcine ascending aorta were randomly divided into 6 groups (n=5). The porcine ascending aorta was decellularized by 5 different protocols in groups A-E: 0.1% trypsin/0.02% ethylenediamine tetraacetic acid (EDTA)/PBS was used in group A, 1%Triton X-100/0.02% EDTA/ distilled water in group B, 1% sodium deoxycholic acid/distilled water in group C, 0.5% sodium deoxycholic acid/0.5% sodium dodecyl sulfate/distilled water in group D, and 1% deoxycholic acid/distilled water in group E; and the porcine ascending aorta was not decellularized as control in group F. The ascending aorta scaffolds were investigated by gross examination, HE staining, DNA quantitative analysis, immunohistochemistry, and scanning electron microscopy were used to observe the efficiency of decellularization, microstructure of the ECM, the damage of collagen type Ⅰ and elastin, the structure of intimal surface, and biomechanical property. The 90 Sprague Dawley rats were randomly divided into 6 groups (n=15). Each scaffold was implanted in the abdominal muscles of rats respectively to evaluate the immunogenicity and biocompatibil ity. ResultsHE staining and quantitative analysis of DNA showed that the cells were completely removed only in groups A and D. The expression of collagen type Ⅰ in group A was significantly lower than that in the other 5 groups (P < 0.05), and serious damage of the basement membrane and decreased beomechanical property were observed. The maximum stress and tensile strength in group A was significantly lower than those in the other groups (P < 0.05), and elongation at break was significantly higher than that in the other groups (P < 0.05). The destruction of collagen type Ⅰ was significant (P < 0.05) in group D, but the basement membrane was integrity, the biomechanical properties were close to the natural blood vessels (group F) (P > 0.05). Implantation results showed that the scaffold of group D had superior immunogenicity and histocompatibility to the scaffold of the other groups. The inflammatory reaction was gentle and the number of the inflammatory cell infiltration was lower in group D than in other groups (P < 0.05). ConclusionIt is concludes that 0.5% sodium deoxycholic acid/0.5% sodium dodecyl sulfate/distilled water is more suitable for the decellularization of porcine aorta, by which the acquired ECM scaffold has the potential for constructing tissue engineered vessel.