Objective To develop a new method for a tissue engineered vascular graft by combining endothelial cells and an acelluarized allogenic matrix. Methods Acellularized matrix tubes were obtained by a 0.1% trypsin and 0 02% EDTA solution for 24 hours and 1% Triton X 100 for 176 hours, respectively. Endothelial cells were isolated from alloaorta and expanded in vitro. Finally, the inner surface of acellularized matrix was reseeded with endothelial cells. Acellularity and reseeding were analysed by light microscopy and scanning electron microscopy. Results The acellularization procedure resulted in an almost complete removal of the original cells and the loose three-dimensional (3D) matrix. The acellular matrix could be reseeded with expanded endothelial cells in vitro, and endothelial cells had the potential of spread and proliferation. Conclusion Acellular matrix produces by Tritoon X-100 and trypsin possesses satisfactory biocompatibility for allogenic endothelial cell. Vascular grafts can be generated in vitro by a combination of endothelial cells and allogenic acelluarized matrix.
ObjectiveTo review the research progress of novel cross-linking methods applied in bio-derived materials. MethodsThe literature about the latest progress in the cross-linking methods of bio-derived materials was reviewed and analyzed. ResultsThe novel cross-linking methods of the bio-derived materials can be divided into chemical methods, physical methods, and biological methods, whose available application and cross-linking properties are greatly depended on their mechanisms. So proper methods should be developed to meet the various application requirements of the materials. A series of studies shows the feasibility and availability of the cross-linked bio-derived materials in the repair and reconstruction of the tissue. ConclusionBio-derived materials modified by novel cross-linking methods are proved to obtain excellent biocompatibility and tissue repair ability, better mechanical properties and degradation properties, and so on. Those methods provide researchers more choices to cross-linking materials, which are help to obtain the clinical tissue engineering products.
ObjectiveTo explore the morphological and functional features of tissue engineered composite constructed with bone mesenchymal stem cells (BMSCs) as seeding cells, thermosensitive collagen hydrogel (TCH) and poly-L-lactic acid (PLLA) as the extracellular matrix (ECM) scaffolds in the dynamic culture system. MethodsBMSCs were separated from long bones of Fischer344 rat, and cultured; and BMSCs at the 3rd generation were seeded on the ECM scaffold constructed with braided PLLA fiber and TCH. The BMSCs-ECM scaffold composite was cultured in the dynamic culture system which was designed by using an oscillating device at a frequency of 0.5 Hz and at swing angle of 70° (experimental group), and in the static culture system (control group) for 7 days. The general observation and scanning electron microscopy (SEM) observation were performed; total DNA content was measured at 0, 1, 3, and 7 days. ResultsPLLA was surrounded by collagen to form translucent gelatiniform in 2 groups; and compact membrane developed on the surface of PLLA. SEM observation showed that BMSCs had high viability and were fusiform in shape with microvilli on the surface of cells, and arranged in line; collagen and cells filled in the pores of PLLA fiber in the experimental group. The cells displayed a flat shape on the surface; there were less cells filling in the pores of PLLA fiber in the control group. At 1, 3, and 7 days, total DNA content in the experimental group was significantly higher than that in control group (P < 0.05). The total DNA content were increased gradually with time in 2 groups, showing significant difference between at 0 day and at 7 days (P < 0.05). ConclusionThe ECM constructed with TCH and PLLA has good biocompatibility. The dynamic cultivation system can promote the cell proliferation, distribution, and alignment on the surface of the composite, so it can be used for tissue engineered composite in vitro.
Objective To determine whether the transforminggrowth factor β1 (TGF-β1) is a key regulatory molecule required for an increase or a balance of extracellular matrix (ECM) and DNA synthesis in the goat passaged nucleus pulposus (NP) cells. Methods The NP cells isolated from the goat intervertebral discs were cultured in vitro for a serial of passages and transfected with the replicationincompetent adenoviral vectors carrying the human TGF-β1 (hTGF-β1) or lacZ genes. Then, they were cultured in monolayer or alginate bead 3dimensional (3-D) systems for 10 days.The changes in the production and the molecular components of ECM that occurredin the NP cells transfected with Ad/hTGF-β1 or the controls were evaluated by Westernblot and absorbance of glycosaminoglycan (GAG)-Alcian Blue complexes. Differences of DNA synthesis in the variant cells and culture systems were assessed by fluorometric analysis of the DNA content. ResultsA quantitation in the variant culture systems indicated that in monolayers the NP cells at Passage 3 transfected with Ad/hTGF-β1 had a much higher cell viability and more DNA synthesis(P＜0.05); however, in the alginate 3-D culture system, the NP cells transfected with Ad/hTGF-β1 did not have any significant difference from the controls(P＞0.05). The Western blotting analysis ofthe protein sample isolated from the variant cells for TGF-β1, type Ⅱ collagen, and Aggrecan expression indicated that in the monolayers and alginate 3-D culture systems the NP cells at Passage 3 transfected with Ad/hTGF-β1 revealed much higher protein levels than the controls(P＜0.05)； whereas the type Ⅰcollagen content was much lower than the controls (P＜0.05), but a significatly increased ratio of type Ⅱ/type Ⅰ collagen was found in both of the cell culture systems(P＜0.05). The GAG quantification also showed a positive result in both the cell culture systems and the NP cells at Passage 3 transfected with Ad/hTGF-β1 had a much higher GAG content than the controls(P＜0.05). Conclusion To a greaterextent, hTGF-β1 can play a key role in maintaining the phenotype of the NP cells and can still have an effect of the phenotypic modulation after a serial of the cell passages. The NP cells that are genetically manipulated to express hTGF-β1 have a promising effect on the restoration of the intervertebral disc defects. The NP cells transfected with Ad/hTGF-β1 cultured in the 3-D alginate bead systems can show a nearly native phenotype.
Objective To review the research progress of osteoblastextracellular matrix(ECM) and its application in bone tissue engineering. Methods The recentrelated literatures were extensively reviewed. Results The ECM was complex in its components. The configuration of cell and cell’s adhesion, migration, proliferation, and differentiation were subject to the ECM. The bioactivity of the tissue engineering products was revealed by ECM, which predicted the product’s efficiency in clinic application. Conclusion ECM has the potential to become the effective index in evaluating tissue engineered products.
ObjectiveTo summarize the regulating mechanism of microRNA in tumor microenvironment. MethodThe literatures about the studies on the mechanism regulated by microRNA for tumor microenvironment were reviewed according to the results searched from PubMed in recent years. ResultsmicroRNA might be participated in regulation of tumor microenvironment factors such as hypoxia-inducible factor, tumor associated fibroblasts, extracellular matrix, which leaded to a change in biological behavior of tumor cells by reforming the microenviroment. ConclusionsmicroRNA has been participated in regulating many factors of tumor microenvironment. The change of neoplastic microenvironment has been recognized to play a critical role in the development of cancer. Therefore revealing microRNA mechanism for tumor microenvironment could not only help exploring the biological behavior of tumor cells, but also come an important insight for new means of diagnosis and treatment of cancer.
The establishing of myocardial tissue engineering techniques not only solve a series of issues that generate in cell and tissue transplantation after myocardial infarction, but also create a platform for selecting better materials and transplantation techniques. However, both experimental animal studies and recent clinical trials indicate that current transplantation techniques still have many defects, mainly including lack of suitable seed cells, low survival rate and low differentiation rate after transplantation. In this context, extracellular matrix （ECM）, as myocardial tissue engineering scaffold materials, has gained increasing attention and become a frontier and focus of medical research in recent years. ECM is no longer merely regarded as a scaffold or a tissue, but plays an important role in providing essential signals to influence major intracellular pathways such as cell proliferation, differentiation and metabolism. The involved models of ECM can be classified into following types：natural biological scaffold materials, synthetic polymer scaffold materials and composite scaffold materials with more balanced physical and biological properties. This review mainly introduces research progress of ECM in myocardial tissue engineering and ECM materials.
【Abstract】Objective To investigate the expression of extracellular matrix metalloproteinase inducer(EMMPRIN)，matrix metalloproteinase-1(MMP1)，MMP9，tissue inhibitors of metalloproteinase-1(TIMP1) and the mast cell count (MCC) and to detect their clinicopathologic significance and relationship in pancreatic cancer tissues. Methods Immunohistochemical method of avidin-biotin complex was used for those 5 targets on the routinely paraffinembedded sections of surgical resected specimen of 51 cases with pancreatic carcinoma. Results The positive rates of EMMPRIN，MMP1，MMP9 and TIMP1 were 56.9%，54.9%，60.8% and 49.0% and its scoring were 2.5±1.5，2.3±1.9，2.4±1.6 and 1.9±1.6 respectively. The mean of MCC was (16.1±6.8)/HP in total cases. The positive rates or scorings of EMMPRIN，MMP1，MMP9 and MCC were significantly lower in high differentiated or without-metastatic cases than in low differentiated or with-metastatic ones(P＜0.05 or P＜0.01), and those targets (except MCC and scoring of MMP9) of middle differentiated ones were lower than those of low differentiated while that of TIMP1 was opposite(P＜0.01). The MCC showed significantly higher in the positive cases of EMMPRIN, MMP1 and MMP9 or negative cases of TIMP1 than in the negative ones of EMMPRIN, MMP1 and MMP9 or positive ones of TIMP1. The closely positive correlations were found among the MCC and the scoring of EMMPRIN, MMP1 and MMP9. The closely negative correlations existed among the scoring of TIMP1 and the other four targets.Conclusion The MCC and the expressions of EMMPRIN, MMP1, MMP9 and TIMP1 might be important biological markers for reflecting the progression and the prognosis of pancreatic carcinoma. They might have co-regulated effects on the potentials of invasion and metastasis of pancreatic carcinoma or other malignant lesions.
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 investigate the expression of connective tissue growth factor（CTGF）in human proliferative membranes of proliferative vitreoretinopathy（PVR），and the relationship among CTGF，transforming growth factor-beta; receptor（TGF-beta;R）and extracellular matrix（ECM）. Methods Immunohistochemistry method of streptavidin-biotin-peroxidase complex（SABC）was used to detect the expression of CTGF，TGF-beta;RⅡ，fibronectin（FN），collagen Ⅰ，and collagen Ⅲ protein in43periretinal membranes（PRM）of PVR obtained by vitrectomy，and the correlations of the expression of CTGF，TGF-beta;RⅡ and ECM were analyzed by statistics. Results CTGF and TGF-beta;RⅡ protein highly expressed in PRM of PVR and most of the CTGF-positive cells were epithelial cells.The result of immunohistochemistry showed that the positive rates of CTGF and TGF-beta;RⅡ protein were 70.6% and 76.5%in PVR C membranes，and 73.9% and 69.6%in PVR D membranes respectively.Relationship between positive expression and membranesprime; grades appeared no statistical correlation(P＞0.05).Statistical analysis showed that there was a correlation between the expression of CTGF and TGF-beta;RⅡ，FN，and collagen Ⅰ and Ⅲ protein，respectively. Conclusions The expression of CTGF and TGFbeta;RⅡ protein is up-regulated in PRM of PVR，which suggests that the activation of TGF-beta;RⅡ is involved in the production of CTGF，and CTGF is closely related to the production of ECM and play an important role in the pathogenesis of PVR. (Chin J Ocul Fundus Dis, 2006, 22: 192-195)