ObjectiveTo analyze the progress in biological tissue engineering scaffold materials and the clinical application, as well as product development status. MethodsBased on extensive investigation in the status of research and application of biological tissue engineering scaffold materials, a comprehensive analysis was made. Meanwhile, a detailed analysis of research and product development was presented. ResultsConsiderable progress has been achieved in research, products transformation, clinical application, and supervision of biological scaffold for tissue engineering. New directions, new technology, and new products are constantly emerging. With the continuous progress of science and technology and continuous improvement of life sciences theory, the new direction and new focus still need to be continuously adjusted in order to meet the clinical needs. ConclusionFrom the aspect of industrial transformation feasibility, acellular scaffolds and extracellular matrix are the most promising new growth of both research and product development in this field.
ObjectiveTo manufacture a polycaprolactone (PCL)/type Ⅰ collagen (COL Ⅰ) tissue engineered meniscus scaffold (hereinafter referred to as PCL/COL Ⅰ meniscus scaffold) by three-dimensional (3D) printing with low temperature deposition technique and to study its physicochemical properties.MethodsFirst, the 15% PCL/4% COLⅠ composite solution and 15% PCL simple solution were prepared. Then, 15% PCL/4% COL Ⅰmeniscus scaffold and 15% PCL meniscal scaffold were prepared by using 3D printing with low temperature deposition techniques. The morphology and microstructure of the scaffolds were observed by gross observation and scanning electron microscope. The compression modulus and tensile modulus of the scaffolds were measured by biomechanical test. The components of the scaffolds were analyzed by Fourier transform infrared spectroscopy (FTIR). The contact angle of the scaffold surface was measured. The meniscus cells of rabbits were cultured with the two scaffold extracts and scaffolds, respectively. After cultured, the cell proliferations were detected by cell counting kit 8 (CCK-8), and the normal cultured cells were used as controls. Cell adhesion and growth of scaffold-cell complex were observed by scanning electron microscope.ResultsAccording to the gross and scanning electron microscope observations, two scaffolds had orientated 3D microstructures and pores, but the surface of the PCL/COLⅠ meniscus scaffold was rougher than the PCL meniscus scaffold. Biomechanical analysis showed that the tensile modulus and compression modulus of the PCL/COL Ⅰ meniscus scaffold were not significantly different from those of the PCL meniscus scaffold (P>0.05). FTIR analysis results showed that COL Ⅰ and PCL were successful mixed in PCL/ COL Ⅰ meniscus scaffolds. The contact angle of PCL/COLⅠ meniscus scaffold [(83.19±7.49)°] was significantly lower than that of PCL meniscus scaffold [(111.13±5.70)°] (t=6.638, P=0.000). The results of the CCK-8 assay indicated that with time, the number of cells cultured in two scaffold extracts showed an increasing trend, and there was no significant difference when compared with the control group (P>0.05). Scanning electron microscope observation showed that the cells attached on the PCL/ COL Ⅰ meniscus scaffold more than that on the PCL scaffold.ConclusionPCL/COLⅠmeniscus scaffolds are prepared by 3D printing with low temperature deposition technique, which has excellent physicochemical properties without cytotoxicity. PCL/COLⅠmeniscus scaffold is expected to be used as the material for meniscus tissue engineering.
ObjectiveTo review the methods of improving the mechanical properties of hydrogels and the research progress in bone tissue engineering. MethodsThe recent domestic and foreign literature on hydrogels in bone tissue engineering was reviewed, and the methods of improving the mechanical properties of hydrogels and the effect of bone repair in vivo and in vitro were summarized. ResultsHydrogels are widely used in bone tissue engineering, but their mechanical properties are poor. Improving the mechanical properties of hydrogels can enhance bone repair. The methods of improving the mechanical properties of hydrogels include the construction of dual network structures, inorganic nanoparticle composites, introduction of conductive materials, and fiber network reinforcement. These methods can improve the mechanical properties of hydrogels to various degrees while also demonstrating a significant bone repair impact. ConclusionThe mechanical properties of hydrogels can be effectively improved by modifying the system, components, and fiber structure, and bone repair can be effectively promoted.
Objective To review the recent advances in the application of graphene oxide (GO) for bone tissue engineering. Methods The latest literature at home and abroad on the GO used in the bone regeneration and repair was reviewed, including general properties of GO, degradation performance, biocompatibility, and application in bone tissue engineering. Results GO has an abundance of oxygen-containing functionalities, high surface area, and good biocompatibility. In addition, it can promote stem cell adhesion, proliferation, and differentiation. Moreover, GO has many advantages in the construction of new composite scaffolds and improvement of the performance of traditional scaffolds. Conclusion GO has been a hot topic in the field of bone tissue engineering due to its excellent physical and chemical properties. And many problems still need to be solved.
Objective To manufacture a poly (lactic-co-glycolic acid) (PLGA) scaffold by low temperature deposition three-dimensional (3D) printing technology, prepare a PLGA/decellularized articular cartilage extracellular matrix (DACECM) cartilage tissue engineered scaffold by combining DACECM, and further investigate its physicochemical properties. Methods PLGA scaffolds were prepared by low temperature deposition 3D printing technology, and DACECM suspensions was prepared by modified physical and chemical decellularization methods. DACECM oriented scaffolds were prepared by using freeze-drying and physicochemical cross-linking techniques. PLGA/DACECM oriented scaffolds were prepared by combining DACECM slurry with PLGA scaffolds. The macroscopic and microscopic structures of the three kinds of scaffolds were observed by general observation and scanning electron microscope. The chemical composition of DACECM oriented scaffold was analyzed by histological and immunohistochemical stainings. The compression modulus of the three kinds of scaffolds were measured by biomechanical test. Three kinds of scaffolds were embedded subcutaneously in Sprague Dawley rats, and HE staining was used to observe immune response. The chondrocytes of New Zealand white rabbits were isolated and cultured, and the three kinds of cell-scaffold complexes were prepared. The growth adhesion of the cells on the scaffolds was observed by scanning electron microscope. Three kinds of scaffold extracts were cultured with L-929 cells, the cells were cultured in DMEM culture medium as control group, and cell counting kit 8 (CCK-8) was used to detect cell proliferation. Results General observation and scanning electron microscope showed that the PLGA scaffold had a smooth surface and large pores; the surface of the DACECM oriented scaffold was rough, which was a 3D structure with loose pores and interconnected; and the PLGA/DACECM oriented scaffold had a rough surface, and the large hole and the small hole were connected to each other to construct a vertical 3D structure. Histological and immunohistochemical qualitative analysis demonstrated that DACECM was completely decellularized, retaining the glycosaminoglycans and collagen typeⅡ. Biomechanical examination showed that the compression modulus of DACECM oriented scaffold was significantly lower than those of the other two scaffolds (P<0.05). There was no significant difference between PLGA scaffold and PLGA/DACECM oriented scaffold (P>0.05). Subcutaneously embedded HE staining of the three scaffolds showed that the immunological rejections of DACECM and PLGA/DACECM oriented scaffolds were significantly weaker than that of the PLGA scaffold. Scanning electron microscope observation of the cell-scaffold complex showed that chondrocytes did not obviously adhere to PLGA scaffold, and a large number of chondrocytes adhered and grew on PLGA/DACECM oriented scaffold and DACECM oriented scaffold. CCK-8 assay showed that with the extension of culture time, the number of cells cultured in the three kinds of scaffold extracts and the control group increased. There was no significant difference in the absorbance (A) value between the groups at each time point (P>0.05). Conclusion The PLGA/DACECM oriented scaffolds have no cytotoxicity, have excellent physicochemical properties, and may become a promising scaffold material of tissue engineered cartilage.
To serve as carriers of cells and bioactive molecules, three-dimensional scaffolds play a key role in bone defect repair. The chemical component and microstructure of the scaffold can affect the mechanical properties and seed cells. A variety of fabrication techniques have been used in producing scaffolds, some made random porous structure, some created well-designed structure using rapid prototyping methods, and others prepared bio-derived materials as scaffolds. However, scaffolds may vary in their inner structure, mechanical properties and repairing efficiency as well because of different manufacturing methods. In this review, we overview the main achievements concerning the effects of material and microstructure on the mechanical performance, seed cells and defect repair of bone scaffolds.
To summarize the medium-term cl inical result of bio-derived bone transplantation in orthopedics with tissue engineering technique. Methods From December 2000 to June 2001, 10 cases of various types of bone defect were treated with tissue engineered bone, which was constructed in vitro by allogenous osteoblasts from periosteum (1 × 106/ mL) with bio-derived bone scaffold following 3 to 7 days co-culture. Six men and 4 women were involved in this study, aged from 14 to 70 years with a median of 42 years. Among them, there were 2 cases of bone cyst, 1 case of non-union of old fracture, 6 cases of fresh comminuted fracture with bone defect, and 1 case of chronic suppurative ostemyel itis. The total weight of tissue engineered bone was 3-15 g in all the cases, averaged 7.3 g in each case. Results The wound in all the case healed by first intention. For 7 year follow up, bone union was completed within 3.0 to 4.5 months in 9 cases, but loosening occurred and the graft was taken out 1 year after operation in 1 case. The X-ray films showed that 9 cases achieved union except one who received resection of the head of humerus. No obvious abnormities were observed, and the function of affected l imbs met daily l ife and work. Conclusion Bio-derived tissue engineered bone has good osteogenesis. No obvious rejection and other compl ications are observed in the cl inical appl ication.
Objective To review the current status and problems in the developing scaffolds for the myocardial tissue engineering appl ication. Methods The l iterature concerning the myocardial tissue engineering scaffold in recent years was reviewed extensively and summarized. Results As one of three elements for tissue engineering, a proper scafold is veryimportant for the prol iferation and differentiation of the seeding cells. The naturally derived and synthetic extracellular matrix (ECM) materials aim to closely resemble the in vivo microenvironment by acting as an active component of the developing tissue construct in myocardial tissue engineering. With the advent and continuous refinement of cell removal techniques, a new class of native ECM has emerged with some striking advantages. Conclusion Through using the principle of composite scaffold, computers and other high-technology nano-polymer technology, surface modification of traditional biological materials in myocardial tissue engineering are expected to provide ideal myocardial scaffolds.
ObjectiveTo observe the feasibility of acellular cartilage extracellular matrix (ACECM) oriented scaffold combined with chondrocytes to construct tissue engineered cartilage.MethodsChondrocytes from the healthy articular cartilage tissue of pig were isolated, cultured, and passaged. The 3rd passage chondrocytes were labeled by PKH26. After MTT demonstrated that PKH26 had no influence on the biological activity of chondrocytes, labeled and unlabeled chondrocytes were seeded on ACECM oriented scaffold and cultivated. The adhesion, growth, and distribution were evaluated by gross observation, inverted microscope, and fluorescence microscope. Scanning electron microscope was used to observe the cellular morphology after cultivation for 3 days. Type Ⅱ collagen immunofluorescent staining was used to check the secretion of extracellular matrix. In addition, the complex of labeled chondrocytes and ACECM oriented scaffold (cell-scaffold complex) was transplanted into the subcutaneous tissue of nude mouse. After transplantation, general physical conditions of nude mouse were observed, and the growth of cell-scaffold complex was observed by molecular fluorescent living imaging system. After 4 weeks, the neotissue was harvested to analyze the properties of articular cartilage tissue by gross morphology and histological staining (Safranin O staining, toluidine blue staining, and typeⅡcollagen immunohistochemical staining).ResultsAfter chondrocytes that were mainly polygon and cobblestone like shape were seeded and cultured on ACECM oriented scaffold for 7 days, the neotissue was translucency and tenacious and cells grew along the oriented scaffold well by inverted microscope and fluorescence microscope. In the subcutaneous microenvironment, the cell-scaffold complex was cartilage-like tissue and abundant cartilage extracellular matrix (typeⅡcollagen) was observed by histological staining and typeⅡcollagen immunohistochemical staining.ConclusionACECM oriented scaffold is benefit to the cell adhesion, proliferation, and oriented growth and successfully constructes the tissue engineered cartilage in nude mouse model, which demonstrates that the ACECM oriented scaffold is promise to be applied in cartilage tissue engineering.
Objective To study the feasibil ity of preparation of the poly-D, L-lactide acid (PDLLA) scaffolds treated by ammonia plasma and subsequent conjugation of Gly-Arg-Gly-Asp-Ser (GRGDS) peptides via amide l inkage formation. Methods PDLLA scaffolds (8 mm diameter, 1 mm thickness) were prepared by solvent casting/particulate leaching procedure and then treated by ammonia plasma. The consequent scaffolds were labeled as aminated PDLLA (A/ PDLLA). The pore size, porosity, and surface water contact angle of groups 0 (un-treated control), 5, 10, and 20 minutes A/ PDLLA were measured. A/PDLLA scaffolds in groups above were immersed into the FITC labelled GRGDS aqueous solutionwhich contain 1-[3-(dimethylamino) propyl]-3-ethylcarbodiimide hydrochloride (EDC.HCl) and N-hydroxysuccinimide(NHS), the molar ratio of peptides/EDC.HCL /NHS was 1.5 ∶ 1.5 ∶ 1.0, then brachytely sloshed for 24 hours in roomtemperature. The consequent scaffolds were labelled as peptides conjugated A/PDLLA (PA/PDLLA). The scaffolds in groups 0, 5, 10, and 20 minutes A/PDLLA and groups correspondingly conjugation of peptides were detected using X-ray photoelectron spectroscopy (XPS). The scaffolds in groups of conjugation of peptides were measured by confocal laser scanning microscope and high performance l iquid chromatography (HPLC), un-treated and un-conjugated scaffolds employed as control. Bone marrow mesenchymal stem cells (BMSCs) from SD rats were isolated and cultured by whole bone marrow adherent culture method. BMSCs at the 3rd–6th passages were seeded to the scaffolds as follows: 20 minutes ammonia plasma treatment (group A/PDLLA), 20 minutes ammonia plasma treatment and conjugation of GRGDS (group PA/PDLLA), and untreated PDLLA control (group PDLLA). After 16 hours of culture, the adhesive cells on scaffolds and the adhesive rate were calculated. After 4 and 8 days of culture, the BMSCs/scaffold composites was observed by scanning electron micorscope (SEM). Results No significant difference in pore size and porosity of PDLLA were observed between before and after ammonia plasma treatments (P gt; 0.05). With increased time of ammonia plasma treatment, the water contact angle of A/PDLLA scaffolds surface was decreased, and the hydrophil icity in the treated scaffolds was improved gradually, showing significant differences when these groups were compared with each other (P lt; 0.001). XPS results indicated that element nitrogen appeared on the surface of PDLLA treated by ammonia plasma. With time passing, the peak N1s became more visible, and the ratio of N/C increased more obviously. AfterPDLLA scaffolds treated for 0, 5, 10, and 20 minutes with ammonia plasma and subsequent conjugation of peptides, the ratio of N/C increased and the peak of S2p appeared on the surface. The confocal laser scanning microscope observation showed that the fluorescence intensity of PA/PDLLA scaffolds increased obviously with treatment time. The amount of peptides conjugated for 10 minutes and 20 minutes PA/PDLLA was detected by HPLC successfully, showing significant differences between 10 minutes and 20 minutes groups (P lt; 0.001). However, the amount of peptides conjugated in un-treated control and 0, 5 minutes PA/PDLLA scaffolds was too small to detect. After 16 hours co-culture of BMSCs/scaffolds, the adhesive cells and the adhesive rates of A/PDLLA and PA/PDLLA scaffolds were higher than those of PDLLA scaffolds, showing significant difference between every 2 groups (P lt; 0.01). Also, SEM observation confirmed that BMSCs proliferation in A/PDLLA and PA/PDLLA groups was more detectable than that in PDLLA group, especially in PA/PDLLA group. Conclusion Ammonia plasma treatment will significantly increase the amount of FITC-GRGDS peptides conjugated to surface of PDLLA via amide l inkage formation. This new type of biomimetic bone has stablized bioactivities and has proved to promote the adhesion and proliferation of BMSCs in PDLLA.