Objective To explore the effects of mechanical stretch with variant frequencies on the alignment and differentiation of the multilayer myotubes cultured in vitro, and to select the optimized cultural condition of regenerative skeletal muscle tissue with stress loading cultured in vitro. Methods C2C12 myoblasts cultured in vitro in the groove casts of Sylgard 184 were induced into the multilayer myotubes. Meanwhile the myoblasts were treated with various mechanical stretch withcells tensile instrument, at the amplitude of 10% and the frequency of 0 (group A), 0.25 (group B), 0.50 (group C), and 1.00 Hz (group D) for 1 hour, 3 times a day. The myotubes morphology was observed by inverted phase contrast microscope at 5, 7, and 10 days after continuous mechanical stretch. And the expressions of mRNA for myogenic differentiation antigen (MyoD), Myogenin, Desmin, and myosin heavy chain (MyHC) were detected by RT-PCR and real-time fluorescent quantitative PCR (QRT-PCR), respectively. Results The mechanical stretch could promote the al igned fusion and increase the number of myotubes. Indeed the multilayer myotubes arranged more closely in group B at 7 days. At the same group, as the time went on, the mRNA expressions of MyoD gradually decl ined in each group. There were significant differences in mRNA expressions of MyoD between 5 days and 7, 10 days (P lt; 0.05). The mRNA expressions of Myogenin, Desmin, and MyHC were highest at 7 days. There were significant differences between different time points (P lt; 0.05), except the mRNA expression of Desmin of group B between 7 and 10 days (P gt; 0.05). At the same time, with the increase of frequency, the highest mRNA expressions of MyoD, Myogenin, Desmin, and MyHC were in group B. There were significant differences at the same time between group B and the other groups (P lt; 0.05), except mRNA expression of Desmin at 5 days between groups B and C, and mRNA expression of MyHC at 10 days between groups A and B (P gt; 0.05). Conclusion Low frequency (0.25 Hz) and suitable time (7 days) periodic mechanical stretch is beneficial to the differentiation of the multilayer myotubes cultured in the groove casts of Sylgard 184, but as the stretch time goes on the aging of myotubes will be accelerated.
OBJECTIVE This paper was to study the biological characteristics of the transformed human embryonic tendon cells, the relation between cell growth and culture conditions, and to compare these features with that of human embryonic tendon cells. METHODS The pts A58H plasmid had successfully used to transform a tendon cell line from human embryo in our past work. The human embryonic tendon cells and the transformed human embryonic tendon cells were cultured in vitro. In different culture conditions, the growth curve were drawn respectively. Population dependence and proliferation capability of the cells were investigated through plate cloning test and soft agar culture. The collagen secreted by cells was identified by immunohistochemical method. RESULTS In routine culture condition, the growth properties of the human embryonic tendon cell and transformed cells were almost identical. The growth properties of the transformed cells were not changed when the cells were frozen storage. There were changes of growth characteristics of the transformed cells when the culture temperature was changed. The transformed cells could subcultured continually and permanently. The proliferation capability of the transformed cells were ber than that of the human embryonic tendon cells. Moreover, the growth of the transformed cells was serum-dependent, and the phenomenon of contact inhibition was observed. The transformed cells were not able to grow on soft agar culture. They had the capacity of secreting collagen type I. CONCLUSION The transformed human embryonic tendon cells could be subcultured continually and permanently, and their growth could be controlled by changing their culture conditions and they had no malignant tendency in biological characteristics. They could be taken as an ideal experimental material for tendon engineering.
Objective As a bioactive material, the osteogenic activity of borate bioglass has been proved. To design a novel borate bioglass according to an improved formula and to investigate the effects of the borate bioglass on osteoblasts invitro for further research and potential cl inical appl ication. Methods The novel Na2O-K2O-MgO-CaO-P2O5-B2O3-SrO borate bioglass was prepared by melting process. The initial and secondary extracts were prepared according to ISO10993-12: 2007 respectively with different extract time of 0-24 hours and 24-48 hours. The osteoblasts (MC3T3-E1) of the 5th-15th passages from mouse were cocultured with the initial (initial extract group) and secondary (secondary extract group) extracts, respectively, to assess the effects of the borate bioglass on the cell prol iferation, protein synthesis, alkal ine phosphatase (ALP) activity, cell apoptosis, and cell migration; while α-MEM medium without addition of extract served as control group. Results The absorbance values at 450 nm were 0.356 0 ± 0.018 7, 0.331 0 ± 0.025 4, and 0.204 0 ± 0.013 8 in initial extract, secondary extract, and control groups, respectively, showing significant differences among 3 groups (P lt; 0.05). The total protein contents were (382.847 ± 9.521), (226.071 ± 5.847), and (220.248 ± 8.213) U in initial extract, secondary extract, and control groups, respectively; there were significant differences between initial extract group and control group, and between initial extract group and secondary group (P lt; 0.05), but there was no significant difference between secondary extract group and control group (P gt; 0.05). However, no significant difference was observed in the ALP activity [(0.013 01 ± 0.000 39), (0.012 93 ± 0.000 44), and (0.012 92 ± 0.000 35) U/ mg], apoptosis rate (7.03% ± 1.95%, 6.46% ± 2.88%, and 6.18% ± 2.21%), horizontal migration [(137.50 ± 11.43), (134.98 ± 10.50), (135.21 ± 8.66) μm], and transmembrane cell number [(10.92 ± 4.99), (10.07 ± 2.50), and (9.81 ± 2.64) cells/ field] among initial extract, secondary extract, and control groups (P gt; 0.05). Conclusion This novel borate bioglass has excellent cytocompatibil ity, which plays regulatory effects on the cell prol iferation, secretion, and migration.
Objective To solve the shortage of hepatocytes for l iver tissue engineering, to explore the possibil ity of prol iferation of rat bone marrow mesenchymal stem cells (BMSCs) and the feasibil ity of differentiation of BMSCs into hepatocyteswith a culture system containing cholestatic rat serum and hepatocyte growth factor (HGF) in vitro. Methods Myeloid cellsof femur and tibia were collected from the female healthy Wistar rats at the age of 6 weeks, the BMSCs were isolated, purified and identified. Normal and cholestatic rat serum were prepared from 40 healthy Wistar rats at the age of 12-14 weeks. The 3rd passage of BMSCs were harvested and added different cultures according to the following grouping: group A, DMEM plus 10%FBS; group B, hepatocyte growth medium (HGM) plus 5%FBS; group C, HGM plus 5% normal rat serum; group D, HGM plus 5% cholestatic rat serum; group E, HGM plus 5% cholestatic rat serum plus 25 μg/L HGF. The changes of cell morphology were observed, MTT assay was used to measure cell growth; the expression of alpha-fetoprotein (AFP) and cytokeratin 18 (CK18) were detected by immunocytochemistry; the glycogen deposit was examined by periodic acid-schiff (PAS) staining; and the urea content in culture supernatant was determined by glutamate dehydrogenase. Results Polygonal cells and binuclear cells were observed in groups D and E, while the shapes of cells in groups A, B, and C did not obviously change. The cell growth curve demonstrated that the speed of cells proliferation in group C was the fastest, the one in group B was the slowest; showing significant differences when compared with groups A, D, and E (P lt; 0.05). On the 7th day in groups D and E, the positive expressions of AFP and CK18 emerged, on the 14th day the positive expression of glycogen emerged. At the same period, the expression ratio was higherin group E than in group D (P lt; 0.05). The urea concentration increased gradually with induction time in groups D and E, the concentration was higher in group E than in group D (P lt; 0.05). No expressions of AFP, CK18, glycogen, and change of the urea concentration were observed in groups A, B, and C. Conclusion Normal rat serum can obviously promote the growth of BMSCs; cholestatic rat serum which promote the growth of BMSCs can induce to differentiate into hepatocyte; and a combination of cholestatic serum and HGF can increase the differentiation ratio.
Objective To explore an effective method of culturing the canine bladder smooth muscle cells, observe the morphological characteristics of the bladder smooth muscle cells growing on acellular small intestinal submucosa（SIS） and offer an experimental basis for reconstruction of the bladder smooth muscle structure by the tissue engineering techniques. Methods The enzymetreatment method and the explant method were respectively used to isolate and harvest the canine bladder smooth muscle cells, and then a primary culture of these cells was performed. The canine bladder smooth musclecells were seeded on the SIS scaffold, and the composite of the bladder smooth muscle cells and the SIS scaffold were co cultured for a further observation. At 5,7 and 9 days of the co culture, the specimens were taken; the bladder smooth muscle cells growing on the SIS scaffold were observed by the hematoxylin staining, the HE staining, and the scanning electron microscopy. The composite of the bladder smooth muscle cells on the SIS scaffold was used as the experimental group, and the bladder smooth muscle cells with no SIS were used as the control group. In each group, 9 holes were chosen for the seeded bladder smooth muscle cells, and then the cells were collected at 3, 5 and 7 days for the cell counting after the enzyme treatment. Morphological characteristics of the cells were observed under the phase contrast microscope and the transmission electron microscope. Expression of the cell specific marker protein was assessed by the immunohistochemical examinaiton. The proliferation of the cells was assessed by the cell counting after the seeding on the SIS scaffold. Results The primary bladder smooth muscle cells that had been harvested by the enzyme treatment method were rapidly proliferated, and the cells had good morphological characteristics. After the primary culture in vitrofor 5 days, the bladder smooth muscle cells grew in confluence. When the bladder smooth muscle cells were seeded by the explant method, a small amount of the spindleshaped bladder smooth muscle cells emigrated from the explant at 3 days. The cells were characterized by the welldeveloped actin filaments inthe cytoplasm and the dense patches in the cell membrane under the transmissionelectron microscope. The immunohistochemical staining showed the canine bladdersmooth muscle cells with positive reacting α actin antibodies. The bladder smooth muscle cells adhered to the surface of the SIS scaffold, growing and proliferating there. After the culture in vitro for 5 days, the smooth muscle cells covered all the surface of the scaffold, showing a singlelayer cellular structure. The cell counts at 3, 5 and 7 days in the experimental group were（16.85±0.79）×105，（39.74±2.16）×105 and （37.15±2.02）×105, respectively. Thecell counts in the control group were（19.43±0.54）×105，（34.50±1.85）×105 and （33.07±1.31）×105, respectively. There was a significant difference between the two groups at 5 days （P＜0.05）. ConclusionWith the enzyme treatment method, the primarily cultured canine bladder smooth muscle cells can produce a great amount of good and active cells in vitro. The acellular SIS can offer an excellent bio scaffold to support the bladder smooth muscle cells to adhere and grow, which has provided the technical foundation for a further experiment on the tissue engineered bladder reconstruction.
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.
Objective To explore a new method for the pre-degeneration of peripheral nerve in vitro for obtaining many effective Schwann cells so as to provide a large number of seed cells for the research and application of tissue engineered nerves. Methods The bone marrow derived cells (BMDCs) from transgenic green fluorescent protein C57BL/6 mouse and the sciatic nerve segments from the C57BL/6 mouse were co-cultured to prepare the pre-degeneration of sciatic nerve in vitro (experimental group, group A), and only sciatic nerve was cultured (control group, group B). At 7 days after culture, whether BMDCs can permeate into the sciatic nerve in vitro for pre-degeneration was observed by gross and immunohistofluorescence staining. And then Schwann cells were obtained from the sciatic nerves by enzymic digestion and cultured. The cell number was counted, and then the purity of primary Schwann cells was determined using immunohistofluorescence staining and flow cytometer analysis. Results At 7 days after pre-degeneration, gross observation showed that enlargement was observed at nerve stumps, and neuroma-like structure formed; the group A was more obvious than group B. Immunohistofluorescence staining showed many BMDCs permeated into the nerve segments, with positive F4/80 staining in group A. After culture, the yield of Schwann cells was (5.59 ± 0.19) × 104 /mg in group A and (3.20 ± 0.21) × 104/mg in group B, showing significant difference (t=2.14, P=0.03). At 48 hours after inoculation, the cells had blue bipolar or tripolar cell nuclei with small size and red soma by immunohistofluorescence staining; fibroblasts were flat polygonal with clear nucleus and nucleolus, showing negative p75NTR staining; and there were few of fibroblasts in group A. The purity of Schwann cells was 88.4% ± 5.8% in group A and 76.1% ± 3.7% in group B, showing significant difference (t=2.38, P=0.04). And the flow cytometer analysis showed that the purity was 89.6% in group A and 74.9% in group B. Conclusion BMDCs can promote the pre-degeneration of peripheral nerve in vitro, and it is a new method to effectively obtain Schwann cells for tissue engineered nerve.
Objective To design a novel stentless porcine aortic bioprosthesis and test the feasibility and its function in vitro after the valve was implanted by a modified method. Methods Six stentless porcine aortic bioprosthesis were divided into two groups according to different implantation, single layer suture group: new improvement stentless porcine aortic bioprosthesis sutured with single layer was implanted; double layer suture group: stentless porcine aortic bioprosthesis developmented by our laboratory used double layer suture was implanted. Each group contained three scales: 23 mm ,25 mm and 27 mm. Analogue ex vivo aortic valve replacement was performed , the feasibility of the new implantation was detected. Effective orifice area, transvalvular pressure gradient and regurgitation ratio were recorded at the cardiac output of 2.0 L/min, 3.5 L/min, 5.0 L/min and 7.0 L/min under the guideline of International Organization for tandardization （ISO）5840. Results The average aortic valve implantation time used for single layer suture and tradition double layer suture were 50 min and 70 min respectively. The transvalvular pressure gradient in the single layer suture group were significantly lower than those in double layer suture group under the flow of 5.0 L/min in 23 mm valve and 27 mm valve （13.51±0.51 mm Hg vs. 14.44±0.99 mm Hg, 7.36±0.19 mm Hg vs. 7.53±0.28 mm Hg；P＜0.01）;and the effective orifice area in the single layer suture group were larger than those in double layer suture group in the same case(1.87±0.06 cm2 vs. 1.76±0.08 cm2, 2.26±0.07 cm2 vs. 2.16±0.05 cm2；P＜0.01). There was no statistically difference in other parameters between both groups. Conclusion The novel design of new improvement stentless porcine aortic bioprosthesis used single layer suture has good hemodynamic characteristics as the nature structure . The modified suture method decrease the implantation time.Nemerical data of the evaluation in vitro show that the difference between single layer suture group and double layer suture group in effective orifice area,transvalvular pressure gradient and regurgitation ratio haveno statistical significance. This experiment is the foundation of the animal and clinical experiment in the future.
OBJECTIVE: To study the technique and method of urethral epithelium culture in vitro, so as to lay the groundwork for reconstructing a tissue engineering urethra and to provide an experimental model of urethral mucosa in physiological, pathological, toxicological and microbiological study. METHODS: The urethral mucosa from a young male New Zealand hare that had just been out of milk, was digested into single cell liquid with Dispase II and mixed enzyme, and the fibroblast were removed. After being seeded, the cells were cultured by using L929 cells as trophoderm. The medium was changed regularly and the cells were subcultured when they grew to mix together 80% to 90%. The cultured cells were analyzed with histochemistry, immunohistochemistry dyeing and flow cytometry examination. We observed the ultrastructure of cells with scanning electron microscope and transmission electron microscope. RESULTS: The primary cultured cells fused when they had been cultured for about ten days. They were the same in size like road rocks. The cultured cells were all epithelial cells without fibroblasts and were diploid cells. The cells could be subcultured 11-13 generations, and could survive 50-60 days. CONCLUSION: The urethral epithelium of young New Zealand hare can be cultured in vitro and maintain the ability to proliferate within a certain time. The study result not only sets a role in reconstructing a tissue engineering urethral mucosa, but also provides an experimental model for the research of urethral mucosa in vitro.
Following the peritendon was removed by means of microsurgical technique, the tenocyte was isolated from the human embryonic tendons by digesting it with trypsin and collagenase. These cells were all stored in frozen condition until they were cultured by F12 culture fluid added with 20% FBS to the 15th generation.These cells were able to grow adhering to the wall and stop growing with contact inhibition. The time of cellsgroup duplication was 4 days, which was similar to the peak time of its mitosis. The number of its chromosome group 2n=46 was 87.5-91.0%. The optimal conditions for tendon cell culture in vitro were investigated, and it was found that after they were reaminated and subcultured the frozen storage didn’t influence their growth, morphology, genetic characteristics. In our research we detected the content generation cells and found the cultured human embryonic tenocyte had same ability never changed with the cells subcultured. We also disscussed the future of tenocyte-a biomaterial in the field of artificial implant.