OBJECTIVE: To build the trestle of tissue engineering for skin with the collagen. METHODS: The collagen was obtained from the baby cattle hide pretreated by Na2S and elastinase and Protease M, then the collagen was dissolved in 0.5 mol/L acetic acid solution. The collagen was treated with Protease N to minimize its immunogenicity. The resulting collagen could be used to build the trestle of tissue engineering for skin because of good biocompatibility. The collagen molecular weight and structure were analyzed by SDS-PAGE. The bioactivity of trestle was tested in the experiment of the mice wound healing and the cell implantation. RESULTS: The SDS-PAGE result of the collagen treated by Protease M showed the typical spectrum of type I collagen. The built trestle was a collagen sponge matrix in which micropore size was 50-200 microns. It could accelerate wound healing and the implanted fibroblasts could proliferate well. CONCLUSION: The collagen treated by Protease N can get good biocompatibilily and is suitable for building the trestles of tissue engineering for skin with good bioactivity.
OBJECTIVE: To fabricate artificial human skin with the tissue engineering methods. METHODS: The artificial epidermis and dermis were fabricated based on the successful achievements of culturing human keratinocytes(Kc) and fibroblasts (Fb) as well as fabrication of collagen lattice. It included: 1. Culture of epidermal keratinocytes and dermal fibroblasts: Kc isolated from adult foreskin by digestion of trypsin-dispase. Followed by comparison from aspects of proliferation, differentiation of the Kc, overgrowth of Fb and cost-benefits. 2. Fabrication of extracellular matrix sponge: collagen was extracted from skin by limited pepsin digestion, purified with primary and step salt fraction, and identified by SDS-PAGE. The matrix lattice was fabricated by freeze-dryer and cross-linked with glutaraldehyde, in which the collagen appeared white, fibrous, connected and formed pores with average dimension of 180 to 260 microns. 3. Fabrication artificial human skin: The artificial skin was fabricated by plating subcultured Kc and Fb separately into the lattice with certain cell density, cultured for one week or so under culture medium, then changed to air-liquid interface, and cultured for intervals. RESULTS: The artificial skin was composed of dermis and epidermis under light microscope. Epidermis of the skin consisted of Kc at various proliferation and differentiation stages, which proliferated and differentiated into basal cell layer, prickle cell layer, granular layer, and cornified layer. Conifilament not only increased in number, but also gathered into bundles. Keratohyalin granules at different development stages increased and became typical. The kinetic process of biochemistry of the skin was coincide with the changes on morphology. CONCLUSION: Tissue engineered skin equivalent has potential prospects in application of repairing skin defect with advantages of safe, effective and practical alternatives.
Objective To compare the attachment and growth of fibroblasts on the different porcine accellular dermal matrix (ADM) so as to find the suitable scaffold for tissue engineering skin. Methods Fibroblasts (5×10 5) were seeded on 4 kinds of ADMs which were crosslinked with glutaraldehyde, uncrosslinked, crosslinked with glutaraldehyde and removed basement membrane, corsslinked with glutaraldehyde and then meshed. The same density fibroblasts were seeded on petri dish as a control. Cell count was done on the 1st, 3rd, 5th days after seeding. The at tachment of fibroblasts on ADM sw as observed by HE staining. Results The grow th and at tachment of fibroblasts on cro sslinked and non2meshed ADM increasedmarkedly w hen compared w ith the o thers. There w as no obvious difference betw een the group s of w ith o r w ithout basement membrane. Conclus ion The above results indicate that non2meshed and co rsslinked w ith glutaraldehyde ADM ismo re suitable fo r the at tachment and grow th of fibroblasts than the o thers and that the modified ADM can be used fo r the scaffo ld of t issue engineering skin.
In order to explore further the regulatory factors to the potentiality in inducing osteogenesis by fibroblasts, the fibroblasts were isolated, and purified from human skin, and were grown in incubation in the media of EGF, IL-6, TNF-alpha and BMP2 at different concentrations for two weeks, then, the markers for osteogenic features were investigated by biochemistry, histochemistry and electron microscopic observations. It was found that the combined use of TNF-alpha and BMP2 could stimulate fibroblasts to secrete alkaline phosphatase, osteocalcin and collagen, and the morphological changes of the fibroblasts were also very striking. In the extracellular matrix, the collagen fibrils, with or without periodicity, were arranged regularly or randomly oriented, and numerous minute calcium granules were interspersed among them. The fibroblasts were interwoven one on top of another in the form of multilayer structure and on the surface, there were secreting granules and piling up of calcium crystals which coalessed steadily and increased in size in forming bony nodules. It was considered that TNF-alpha and BMP2 were capable of inducing the fibroblasts to form bone.
Primary human hepatocytes (PHH) are the gold standard of in vitro human liver model for drug screening. However, a problem of culturing PHH in vitro is the rapid decline of cytochrome P450 (CYP450) activity, which plays an important role in drug metabolism. In this study, thermo-responsive culture dishes were used to explore the conditions for murine embryonic 3T3-J2 fibroblasts to form cell sheet. Based on the cell sheet engineering technology, a three-dimensional (3D) “sandwich” co-culture system of 3T3-J2 cell sheet/PHH/collagen gel was constructed. The tissue structure and protein expression of the model section were observed by hematoxylin eosin staining and immunofluorescence staining respectively. Phenacetin and bupropion were used as substrates to determine the activity of CYP450. The contents of albumin and urea in the system were determined by enzyme linked immunosorbent assay (ELISA). The results showed that the complete 3T3-J2 cell sheet could be obtained when the cell seeding density was 1.5×106 /dish (35 mm dish) and the incubation time at low temperature was 60 min. Through cell sheet stacking, a 3D in vitro liver model was developed. Compared with the two-dimensional (2D) model, in the 3D model, the cell-cell and cell-matrix connections were tighter, the activities of cytochrome P450 CYP1A2 and cytochrome P450 CYP2B6 were significantly increased, and the secretion levels of albumin and urea were increased. These indexes could be maintained stably for 21 d. Therefore, cell sheet stacking is helpful to improve the level of liver function of 3D liver model. This model is expected to be used to predict the metabolism of low-clearance drugs in preclinical, which is of great significance for drug evaluation and other studies.
OBJECTIVE: To study the stimulating effects of basic fibroblast growth factor(bFGF) on fibroblast function and its ability to expression of c-fos gene. Furthermore, to explore the possible network action between bFGF and oncogene in modulating wound healing. METHODS: Cultured rat fibroblasts were divided into bFGF stimulating group and control group. Fibroblasts in bFGF stimulating group were treated with bFGF in a dosage of 40 ng/culture hole, while the control fibroblasts were treated with the same vehicle without bFGF. The morphology, cell vitality and their ability to express c-fos gene in the fibroblasts in both groups were studied with MTT and immunohistochemical methods. RESULTS: All fibroblasts in bFGF treated groups were enlarged and showed increased vitality with MTT method. C-fos gene expression in bFGF stimulating group was increased, especially in nucleus when compared with those in control group. CONCLUSION: The results show that the function and the ability to express c-fos gene in bFGF treated fibroblasts are enhanced. Combined with our previous studies, it may make a conclusion that there is a network regulation mechanism between growth factors and some oncogenes.
ObjectiveTo investigate the expression and relation of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in rats with diabetic retinopathy.MethodFifty-five Wistar rats were randomly divided into the control group (10 rats), and 1, 3, and 5-month-diabetes group (15 rats in each diabetes group), and the diabetic models were set up. The expressions of VEGF and bFGF were detected by situ hybridation and immunohistochemistry on retinal paraffin sections.ResultsThe results of situ hybridation showed that expression of bFGF was found in 3-month-deatbtes group with the percentage of 77.8%, and 88.9% in 5-month-deatbtes group; the positive expression of VEGF was not found in 3-month-deatbtes group but in 5-month-deatbtes group with the percentage of 66.7%. Immunohistochemistry indicated that the positive expression of bFGF started in 3-month-deatbtes group with the percentage of 55.6%, and 88.9% in 5-month-deatbtes group; the percentage of the expression of VEGF was 33.3% in 3-month-deatbtes group and 88.9% in 5-month-deatbtes group.ConclusionThe expression of VEGF occurs after the expression of bFGF in rats with DR.(Chin J Ocul Fundus Dis, 2005,21:37-40)
Objective To observe the effect of exogenous basic fibrob last growth factor (bFGF) on apoptosis of cultured human retinal pigment epithelial (RPE) cells exposed to visible light,and determine the role of bFGF, fibroblast growth factor receptor 1 (FGFR1),bcl-2 and caspase-3. Methods 2000±500) lx cold white light was used. Exogenous bFGF was utilized during culture. Annexin annexin V-fluoresce in isothiocyanate/propidium iodium (V-FITC/PI) labeling,flow cytometry, Immunocytochemical staining, enzyme associated absorb examing and reverse transcriptional polymerase chain reaction (RT-PCR) were used to determine the apoptosis, the expression levels of bFGF, FGFR1, bcl-2, as well as the activity of caspase-3. Results No protective effect of bFGF was observed under the concentration 5 ng/ml.A significant inhibition of apoptosis was found in 10 ng/ml and 20 ng/ml groups （P＜0.05）. The upregulation of bcl-2 was observed in bFGF (10 ng/ml, 20 ng/ml) protreated groups（P＜0.01）.Compared to no light exposure group,all light exposure groups (including bFGF pro-treated) had higher endogenous bFGF and FGFR1 levels （P ＜0.05）, and the increase was concentration dependent.The bFGF and FGFR1 levels were higher in exogenous bFGF applied (gt;5 ng/ml) groups than light exposure groups（P＜0.05）. The caspase-3 activity was significantly inhibited in bFGF (10 ng/ml) pro-treated groups. Conclusions Human RPE cells exposed to visible light were rescued by application of exogenous bFGF in vitro.The probable protective mechanism of bFGF partly is directly binding to FGFR1 or potentiating endogenous bFGF autocrine loop,to upregulate bcl-2 and to inhibit caspase-3 activation. (Chin J Ocul Fundus Dis，2003，19：24-28)
Objective To construct human brain-derived neurotrophic factor retroviral vector-pLXSN (hBDNFpLXSN), and to evaluate the bioactivity of hBDNF. Methods The genome mRNA was extracted from embryonic brain tissue of a 5-month-old infant, the hBDNF gene sequence was obtained with RT-PCR technology, and hBDNF-pLXSN constructed in vitro was used to infect the fibroblasts (NIH/3T3). The expression of hBDNF was identfied by the immunohistochemistry method, and the NIH/3T3 and BDNF biological activities were determined by culture of the PC12 cells and dorsal root gangl ia. Results The hBDNF-pLXSN was constructed successfully by sequencing analyses. The infected NIH/3T3 showed positive expression of hBDNF. The infected NIH/3T3 could product hBDNF. Bioactivity of the products could support the PC12cell survival and neurite growth in the primary cultures of dorsal root gangl ia neurons of mice. Conclusion hBDNF-pLXSNvirus has the abil ity to infect NIH/3T3 and make it expressed and secreted hBDNF with the biological activity. It can be used to treat facial paralysis as a gene therapy.
OBJECTIVE: To analysis the biological characteristics of human fibroblasts transfected by human telomerase reverse transcriptase (hTERT) eucaryotic expression plasmid pGRN145. METHODS: Fibroblasts from children’s foreskin were isolated and cultured in vitro, and the fibroblasts were transfected by pGRN145 with Lipofec-tAMINE PLUS Reagent. After strict screening of hygromycin B, the positive clones were subcultured. The telomerase activity was detected by RT-PCR and TRAP-PCR technique. The cell generation cycle and apoptosis rate were detected by flow cytometry to investigate the proliferative characteristics after transfection, and the chromosome karyotype of transformed cells was analyzed. The collagen secreted by transformed cells was detected by immunohistochemical staining. RESULTS: The morphological properties of fibroblasts did not change obviously after transfection. There were telomerase activity in transfected fibroblasts, while it could not be detected in pre-transfection fibroblasts. The cell generation cycle had no obvious changes between pre-transfection and post-transfection. However, the apoptosis rate of transfected fibroblasts were decreased compared with that of pre-transfection. The fibroblasts transfected by pGRN145 maintained the normal diploid karyotype, as well as the cells could normally secret type I and III collagen. CONCLUSION: The human fibroblasts transfected by pGRN145 has telomerase activity with prolonged life span of culture, which preliminarily proves the availability of establishing standard seeding cell lines of tissue engineering by hTERT plasmid transfection techniques.