Objective To review the research progress of cell-scaffold complex in the tendon tissue engineering. Methods Recent literature concerning cell-scaffold complex in the tendon tissue engineering was reviewed, the research situation of the cell-scaffold complex was elaborated in the aspects of seed cells, scaffolds, cell culture, and application. Results In tendon tissue engineering, a cell-scaffold complex is built by appropriate seed cells and engineered scaffolds. Experiments showed that modified seed cells had better therapeutic effects. Further, scaffold functionality could be improved through surface modification, growth factor cure, mechanical stimulation, and contact guidance. Among these methods, mechanical stimulation revealed the most significant results in promoting cell proliferation and function. Through a variety of defect models, it is demonstrated that the use of cell-scaffold complex could achieve satisfactory results for tendon regeneration. Conclusion The cell-scaffold complex for tendon tissue engineering is a popular research topic. Although it has not yet met the requirement of clinical use, it has broad application prospects.
Objective To explore the effects of mechanical stimulation on the expression of autoantigens in myoblasts. Methods According to different processing methods, C2C12 cells were divided into the experimental group and control group; the experimental group was divided into 4 subgroups: 2-, 4-, and 6-day and 1-day stretch groups. In 2-, 4-, and 6-day stretch groups, mechanical loading was added on the C2C12 cells at a stretching frequency of 0.25 Hz and cellular deformation amplitude of 10%, 2 hours a day for 2, 4, and 6 days respectively by Flexercell 5000 strain unit, and at a stretching frequency of 1 Hz and cellular deformation amplitude of 15% for 1 hour in 1-day stretch group. In the control group, the cells were routinely cultured for 1, 2, 4, and 6 days (1-, 2-, 4-, and 6-day control). The cells were observed by inverted phase contrast microscope. The cell proliferation was detected by flow cytometry; the expressions of autoantigens were detected by Western blot method, including the Ku/the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), U1-70 (A part of ATP-dependent DNA helicase II), histidyl tRNA synthetase (HRS), and Mi-2 (reconfigurable components deacetylase complexes of NuRD). Results The exfoliated cells were found in 1-day stretch group, but no exfoliated cell was seen in the control group for 1-day culture. The cells proliferated more obviously in 2-day stretch group than in the control group for 2-day culture; cell differentiation was found in 4-day stretch group, and cell fusion in 6-day stretch group, which were similar to those in the control group for 4- and 6-day culture. After single stretching, cell apoptosis was found in 1-day stretch group, showing no significant difference in the relative DNA proliferation index (DPI) when compared with DPI of control group for 1-day culture (t=0.346, P=0.747). After cyclic stretching, DPIs of 2- and 4- day stretch groups were significantly increased when compared with those of the control group for 2- and 4-day culture (P lt; 0.05), but no significant difference was found between control group for 6-day culture and 6-day stretch group (t=1.191, P=0.303). Compared with the control group for 2-day culture, the relative protein expression of autoantigens (DNA-Pkcs, Mi-2, HRS, and U1-70) in 2-day stretch group decreased significantly (P lt; 0.05), but no significant difference was found between control group for 4-day culture and 4-day stretch group (P gt; 0.05). The relative protein expressions of autoantigens in 4-day stretch group significantly increased when compared with those of 2-day stretch group (P lt; 0.05), but the relative protein expressions of autoantigens in the control group for 4-day culture significantly decreased when compared with those of the control group for 2-day culture (P lt; 0.05). Conclusion Short-term mechanical stimulation can inhibit the expressions of autoantigens in myoblasts, but with the time prolonging, cell differentiation and fusion and adaptation to mechanical stimulation would result in diminished inhibitory effect.
Objective Mechanical stimulation and inductive factors are both crucial aspects in tissue engineered cartilage. To evaluate the effects of mechanical stimulation combined with inductive factors on the differentiation of tissue engineered cartilage. Methods Bone marrow mesenchymal stem cells (BMSCs) were isolated from newborn porcine (aged7 days and weighing 3-6 kg) and expanded in vitro. The BMSCs at passage 2 were seeded onto a scaffold of poly (lactic-coglycol ic acid) (PLGA) in the concentration of 5 × 107/mL to prepare cell-scaffold composite. Cell-scaffold composites were cultivated in a medium with chondrocyte-inducted factors (group A), in a vessel with mechanic stimulating only (group B), or mechanic stimulating combined with chondrocyte-inducted factors (group C) (parameters of mechanics: 1 Hz, 0.5 MPa, and 4 hours/day). Cell-scaffold composite and auto-cartilage served as positive control (group D) and negative control (group E), respectively. After 4 weeks of cultivation, the thickness, elastic modulus, and glycosaminoglycan (GAG) content of composites were measured. Additionally, BMSCs chondrogenic differentiation was assessed via real-time fluorescent quantitative PCR, immunohistochemistry, and histological staining. Results The thickness, elastic modulus, and maximum load in group C were significantly higher than those in groups A and B (P lt; 0.05). In groups A, B, and C, cartilage lacuna formation, GAG expression, and positive results for collagen type II were obsersed through HE staining, Safranin-O staining, and immunohistochemistry staining. The dyeing depth was deeper in group A than in group B, and in group C than in groups A and B; group C was close to group E. The GAG content in group C was significantly higher than that in groups A and B (P lt; 0.05). Real-time fluorescent quantitative PCR revealed that mRNA expressions of collagen type I, collagen type II, and GAG in group C were significantly higher than those in groups A and B (P lt; 0.05), and in group A than in group B (P lt; 0.05). Conclusion Mechanical stimulation combined with chondrocyte inductive factors can enhance the mechanical properties of the composite and induce higher expression of collagen and GAG of BMSCs.
Objective To review the research and appl ication of functional tissue engineered tendons (FTETs). Methods Recent l iterature concerning the research of FTETs was reviewed and analyzed. Results Functional tissue engineering (FTE) was a new approach that placed an emphasis on the importance of mechanical stress in determining the success of tissue engineered constructs and the effect of tissue remodel ing in vivo. The concept of FTE was introduecd into the research of tissue engineered tendons; by measuring in vivo loads of normal tendon and using the information as a guidel ine, theappropriate tissue engineered tendon which can withstand in vivo loads was designed. It would be possible to solve the problems that the biomechanical function of the tissue engineered tendons could not meet the requirements of the loading environment in vivo. Conclusion FTETs have a more promising future for the treatment of tendon defects.
ObjectiveTo review the relative researches about mechanical stimulation of stem cells differentiation in stem cells microenvironment in vitro. MethodsThe recent related literature about stem cells differentiation in vitro was reviewed and summarized. ResultsThe mechanical loads (including shear stress, mechanical strain, and stress), substrates stiffness, substrates nanotopography, and cell shape were the 4 important aspects of mechanical factors regulating stem cells differentiation. The mechanical stimulation can simulate the in vivo microenvironment, which can alter the size, shape, alignment, and differentiation state of stem cells, can change the expression of their differentiation markers, and can affect the lineage commitment of stem cells. ConclusionMechanical stimulation play an important role in regulating stem cells differentiation and cells morphology in addition to chemical and biological factors.