Objective Choose polylactide-co-glycolide/hydroxyapatite (PLGA/HA) and porous phosphate calcium (PPC) as the object that we will study, compare their degradabality and choose one as a suitable scaffold for rib reconstruction. Methods All the experiments were divided into PLGA/HA group and CPC group. Degradabality experiment in exvivo: put the two scaffold which have the same size into 0.9% NaCl, keep sterile, then put the container into warm cage，get out and weigh them in 2, 4, 8, 12 and 24 weeks, compare the different speed of the two scaffold. Degradability experiment in vivo: put the two scaffold which have the same size under the skin of the rabbit, and weigh them in 2, 4, 8, 12 and 24 weeks, the tissue around the scaffold was examinzed by HE and the scaffold was examined by electron scanning microscope. Results Micro-CT and Scanning electron microscopy shows that CPC group had better structure （1101.2228±0.6184 mg/ccm vs. 1072.5523±0.7442 mg/ccm）and porosity（70.26％±0.45％ vs.72.82％±0.51％）than PLGA/HA group; The result of degradabality experiment in vitro shows that the speed of the two scaffolds was slow. It is at 24 weeks that the degradability is obvious,and the PLGA/HA group degraded a lot which was 60%. The result of degradabality experiment in vivo shows that the speed of degradabality of PLGA/HA group was faster than that is in the 0.9% Nacl, also was faster than that of CPC group which was 96%.The reponse of tissue around the PLGA/HA was more sever than that of CPC group which is in favour of the growth of cells. Conclusion As for the reconstruction of large defect of rib, CPC is more suitable than PLGA/HA.
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 investigate the way and process of degradation behavior of acellular porcine aortic valve in vitro. Methods Acellular porcine aortic valve（n=90）were randomly divided into 3 groups （collagenase group, elastase group, control group）, 30 piece in each group . Behavior of acellular porcine aortic valve was degradated with 0.05mg/ml collagenase Ⅰ, 0. 05mg/ml elastase, phosphate buffered solution in collagenase group, elastase group and control group. The histomorphology, weight loss, value of protein and hydroxyproline were observed at 3,6,9, 12, 15 and 30d after degradation. Results The behavior of acellular porcine aortic valve of collagenase group and elastase group became poorer, looser and broken gradually in degradation. The weight loss of valve, the value of protein and hydroxyproline in vehiculum became greater gradually in collagenase group and elastase group（P〈0. 01）. Furthermore the effect of collagenase Ⅰ was b than elastase in degradation. Conclusion The effect of collagenase Ⅰ and elastase can degradate the acellular porcine aortic valve in vitro. Collagenase Ⅰ is b than elastase in degradation.
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 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 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 the cytotoxicity, labeled time, marking rate, and effect on adhesion of quantum dot 655 (QD655) labeled rat bone marrow mesenchymal stem cells (BMSCs) in vitro, and to confirm its feasibil ity for stem cell label ing and tracer means for rat. Methods BMSCs were collected from the femur and tibia bone marrow cavity of a 2-week-old SD rat, cultured and identified. The 3rd passage of BMSCs were incubated with QD655 as the experimental groupaccording to the recommended concentration of the markers. The cells were not labeled by QD655 as control group. Thecell survival rate after QD655 label ing was detected by trypan-blue exclusion. The effect of QD655 on cell prol iferation was observed by MTT. The osteogenic differentiation potential was identified by Al izarin red staining, alkal ine phosphatase (ALP) staining, and real-time fluorogenic quantitative PCR. At immediately, 1, 2, 4, and 6 weeks, fluorescent microscopy was used to observe the labeled rate and scanning electron microscope was used to observe the cell adhesion to scaffold (bioglass/collagen composite). Results The cell survival rates were more than 90% in both experimental group and control group, showing no significant difference (P gt; 0.05). There was no significant difference in the cell prol iferation between 2 groups (P gt; 0.05). Al izarin red staining and ALP staining showed positive results. Real-time fluorogenic quantitative PCR result showed that the mRNA expression levels of osteopontin, osteocalcin, collagen type I, ALP, and BMP-2 in the experimental group was significantly higher than those in the control group. The labeled rates were 96.50% ± 1.59%, 93.30% ± 1.51%, 72.40% ± 2.90%, 40.10% ± 3.60%, and 10.00% ± 1.70% immediately, 1, 2, 4, and 6 weeks after label ing, respectively. The labeled rate in the control group was 0. Scanning electron microscope showed a good distribution of fusiform or polygonal cells in the pores of scaffold. Conclusion QD655 can be used as a label ing marker for BMSCs. Rat BMSCs labeled with QD655 is of high efficiency and safety.
Objective The biological effects of fibroblast growth factor (FGF) may be different under different intensities and durations. To investigate the impact of sustained increasing FGF signal upon the development of epiphyseal plate. Methods Epiphyseal plates cultured in vitro were obtained from embryonic C57BL/6J mice, and were divided into control group (0.1% DMSO), basic FGF (bFGF) group (100 μg/L bFGF and 0.1% DMSO), and PD98059 group (100 μg/L bFGF and 50 μmol/L PD98059 with 0.1% DMSO). The total length (TL) and ossified tissue length (OSL) of the cultured bones weremeasured with Calcein staining 6 days after culture. The expressions of Indian hedgehog (Ihh), collagen type II (Col II), and Col X genes were detected by real-time fluorescent quantative PCR 7 days after culture. Results The embryonic bones cultured in vitro continued growth. At 6 days after culture, there was no significant difference in increased percentage of TL between bFGF group and control group (P gt; 0.05), the increased percentage of OSL in bFGF group was significantly less than that in control group (P lt; 0.05). There was no significant difference in the increased percentage of TL and OSL between PD98059 group and control group (P gt; 0.05), but they were significantly higher than those of bFGF group (P lt; 0.05). At 7 days after culture, the gene expressions of Ihh, Col II, and Col X in bFGF group significantly decreased when compared with those in control group (P lt; 0.05). There was no significant difference in the gene expressions of Col II and Col X between PD98059 group and control group (P gt; 0.05), but the gene expressions were significantly higher than those of bFGF group (P lt; 0.05); the expression of Ihh in PD98059 group was significantly higher than that in control group and bFGF group (P lt; 0.05). Conclusion Sustained increasing FGF signal may affect the Col II and Col X expressions by down-regulating Ihh, which may lead to the development retardation of epiphyseal plate cultured in vitro. The external signal regulated kinase pathway may play an important role in the process.
Objective To compare the myogenic differentiation abil ity in vitro of rabbit adipose-derived stem cells (ADCSs) from different sites so as to provide ideal seed cells for repair and reconstruction of urinary tract. Methods Adipose tissues were obtained from the nape of the neck, post peritoneum, and vicinity of epididymis of a 4-month-old male New Zealand rabbit and ADSCs were harvested through collagenase digestion. ADSCs were purified by differential attachment method. The protein marker CD44 of rabbit ADSCs was used to identify the stem cells by immunocytochemistry, then the5th generation of ADSCs were induced to differentiate into adipogenic, osteogenic, and myogenic cells. Multi- differentiation was confirmed by Oil red O staining, von Kossa staining, and RT-PCR. Myogenic differentiation abil ities of ADSCs from 3 different sites were compared between the control group (L-DMEM medium containing 10%FBS) and the experimental group (myogenic medium) by RT-PCR method. Results ADSCs could be easily isolated from adipose tissues of the nape of the neck, post peritoneum, and vicinity of epididymis. ADSCs displayed a typical cobblestone morphology. Brown particles could be seen in ADSCs by CD44 immunocytochemistry staining. Oil red O staining showed red fat drops in ADSCs after 14 days of adipogenic culture. Black matrix could be seen in ADSCs by von Kossa staining after 28 days of osteogenic culture. RT-PCR detection showed moderate α-actin expression in the control group and b α-actin expression in the experimental group after 42 days of myogenic culture. The growth rate of α-actin from the adipose tissue of post peritoneum (28.622% ± 4.879%) was significantly lower (P lt; 0.05) than those from the adipose tissues of the nape of the neck (35.471% ± 3.434%) and vicinity of epididymis (38.446% ± 4.852%). Conclusion The ADSCs from different sites show different myogenic differentiation abil ities in vitro. ADSCs from the adipose tissues of the nape of the neck and vicinity of epididymis can be used as ideal seed cells for tissue engineering of lower urinary tract.