OBJECTIVE: To review the role of matrix metalloproteinase-1 (MMP-1) in the course of healing in wounded skin. METHODS: The recent literatures on MMP-1 in skin wound repair were reviewed, which gave the insight into the local effect of MMP-1 during re-epithelialization. RESULTS: Following injury, basal keratinocytes, moving from the wound edge and interact with dermal matrix proteins in the wound bed, were induced to express MMP-1 in a specific space-time pattern. MMP-1 cleaved the collagen, thereby altering its structure and affinity by which the keratinocytes binded it. MMP-1 served a beneficial role in wound healing by facilitating the proliferation and movement of keratinocytes over the collagen-rich wound bed during re-epithelialization. CONCLUSION: MMP-1 expression of migrating keratinocytes directly influences the re-epithelialization during the course of healing of the wounded skin.
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.
Objective To review the current research status and clinical application progress of extracellular matrix (ECM) material in tissue engineering. Methods The literature about the latest progress in the preparation, biocompatibility, mechanical property, degradability, and clinical application of ECM material was extensively reviewed. Results The improvement of the ECM preparation method and thorough understanding of the immunological properties have laid the foundation for the repair and reconstruction of the tissue. Moreover, a series of animal studies also confirm that the feasibility and effectiveness of the ECM such as small intestinal submucosa, bladder ECM grift, and acellular dermis which have been applied to the repair and reconstruction of the urethra, bladder, arteries, and skin tissue. It shows a wide prospect of clinical application in the future. Conclusion ECM material is a good bio-derived scaffold, which is expected to become an important source of alternative materials for the repair and reconstruction of the tissue.
OBJECTIVE: To investigate the effects of trace elements on the metabolism of extracellular matrix and explore the physiological and pathological mechanism of trauma. METHODS: Based on the experimental and clinical data, it was studied that the action of trace elements in the metabolism of extracellular matrix in trauma repairing. RESULTS: During wound healing, the trace elements were the components of many kinds of enzymes, carriers and proteins. They took part in the synthesis of hormones and vitamins as well as the transmission of information system. They activated many different kinds of enzymes and regulate the levels of free radicals. The trace elements had the complicated effects on the synthesis, decompose, deposition and reconstruction of collagen and other extracellular matrix. CONCLUSION: The trace elements play an important role in regulating the metabolism of extracellular matrix.
ObjectiveTo investigate the mechanism of mTOR signaling pathway in bleomycin (BLM)-induced pulmonary fibrosis in mice.MethodsSixty C57BL/6 mice were randomly divided into a control group and a BLM group. Pulmonary fibrosis model was induced by single intratracheal instillation of bleomycin (2.5 mg/kg) in the BLM group. Similarly, 0.9% saline was instilled directly into the trachea in the control group. Then all mice were sacrificed at 21 days. The lungs were collected for morphometric analysis with HE and Masson staining. The degree of pulmonary fibrosis was evaluated with Ashcroft score. The activity of mTOR signaling pathway was measured by Western blot. The level of collagen1, collagen3 mRNA was assessed with quantitative real time PCR.ResultsThe thickening alveolar septa, accumulation of inflammatory cells, and fibrous obliteration in the BLM group were exhibited predominantly compared with the control group. There was a significant difference in Ashcroft score between the BLM group and the control (P<0.05). Also, the activity of mTOR signaling pathway was up-regulated and the expression of collagen1 mRNA and collagen3 mRNA was increased in the BLM group.ConclusionAberrant activation of mTOR signaling pathway aggravates the pulmonary fibrogenesis.
Objective To investigate the feasibil ity of preparing the porous extracellular matrix (ECM) by use of some chemicals and enzymes to decellularize the porcine carotid artery. Methods The porcine carotid artery was procured, and warm ischemia time was less than 30 minunts. The porcine carotid artery was decellularized with 1% sodium dodecyl sulfate (SDS) for 60 hours to prepare common ECM; then common ECM was treated with 0.25% trypsin (for 6 hours) and 0.3 U/ mL collagenase (for 24 hours) to prepare porous ECM. The common ECM and porous ECM were stained with HE,Masson’s trichrome, and Orcein to evaluate the histological features. Then the mechanical property, cytotoxicity, and pore size of ECMs were determined. After 4 weeks of subcutaneous implantation in dogs, the histological examination was used for the study. Results Histological observation confirmed that 2 kinds of ECMs were decellularized completely and more porous structure was observed in porous ECM. Scanning electron microscope showed the pores in porous ECM were greater and the length of shorter axis in porous ECM ranged from 5 to 30 μm, the length of longer axis from 40 to 100 μm. The porosity of porous ECM (99.25%) was greater than that of common ECM (91.50%). The burst pressure of porous ECM decreased when compared with common ECM, showing significant difference [(0.154 3 ± 0.012 7) MPa vs [0.305 2 ± 0.015 7) MPa, P lt; 0.05]. There was no significant difference in suture retention strength between 2 kinds of ECMs (P gt; 0.05). The cytotoxicity test showed no obvious cytotoxicity in 2 kinds of ECMs. In vivo implantation test showed that the deeper host cells infiltration and more neo-microvessels in porous ECM were observed than in common ECM. Conclusion SDS and some enzymes can be used to prepare porous ECM as the scaffold for tissue engineered blood vessels.
ObjectiveTo review the progress of cell sheet technology (CST) and its application in bone tissue engineering. MethodsThe literature concerning CST and its application was extensively reviewed and analyzed. ResultsCST using temperature-responsive culture dishes is applied to avoid the shortcomings of traditional tissue engineering. All cultured cells are harvested as intact sheets along with their deposited extracellular matrix. Avoiding the use of proteolytic enzymes, cell sheet composed of the cells and extracellular matrix derived from the cells, and remained the relative protein and biological activity factors. Consequently, cell sheet can provide a suitable microenvironment for the bone regeneration in vivo. With CST, cell sheet engineering is allowed for tissue regeneration by the creation of three-dimensional structures via the layering of individual cell sheets, be created by wrapping scaffold with cell sheets, or be created by folding the cell sheets, showing great potential in tissue engineered bone. ConclusionConstructing tissue engineered bone using CST and traditional method of bone tissue engineering will promote the development of the bone tissue engineering.
Patients with pathological tracheal loss more than a certain length may need tracheal transplantation.Traditional natural tissue and autologous tissue have failed to produce satisfactory clinical outcomes to replace the trachea because of local infection，tracheal stenosis，tracheomalacia，immune rejection et al. In recent years，the emergence oftissue engineering trachea provides a new idea for tracheal transplantation. But scientists have not yet reached a consensus about how to choose ideal extracellular matrix to construct tissue engineering trachea. At present research and applicationof tissue engineering trachea，extracellular matrices mainly include allogenic trachea，allogenic aorta and biologicalcomposite materials. Each allogenic matrix or biological composite material has its own advantages and disadvantages. Therefore，this article mainly summarizes recent application and research progress of extracellular matrix in long segmental tracheal defect and its future perspective.
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)
ObjectiveTo investigate the effect of hydrogel from acellular porcine adipose tissue (HAPA) on the survival of transplanted adipose tissue.MethodsFor in vitro study, adipose tissue and HAPA-adipose tissue complex were cultured in normoxia and hypoxia atmospheres for 24 and 72 hours. TUNEL and Perilipin immunofluorescence staining were performed to observe the effect of HAPA on apoptosis and survival of adipocities. For in vivo study, 42 healthy male nude mice (4-6 weeks old) weighing 15-18 g were randomly divided into adipose group (group A), 10%HAPA group (group B), 20%HAPA group (group C), 30%HAPA group (group D), 40%HAPA group (group E), and 50%HAPA group (group F) according to different HAPA/adipose tissue volume ratio (n=7). For each group, 1 mL adipose tissue or HAPA-adipose tissue complex was injected subcutaneously into the dorsum of the nude mice. At 4 weeks after transplantation, 7 nude mice in each group were sacrificed and grafts were harvested, gross observation, volume measurement, ultrasound examination, and histologic staining (HE staining, CD31 and Perilipin immunofluorescence stainings) were applied.ResultsHypoxia showed a tendency of promoting adipose tissue necrosis and apoptosis, while HAPA exhibited an obvious effect of inhibiting cell apoptosis in vitro study (P<0.05). For in vivo study, grafts of all groups had intact fibrocapsule. No obvious signs of infection and necrosis were observed at 4 weeks. Volume shrinkage was observed in all groups, however, the groups A-D had significantly higher volume retention rate than groups E and F (P<0.05). Ultrasound examination showed that there were no significant difference in the number and volume of liquify area of the grafts in each group (P>0.05). With the increase of HAPA’s volume ratio, HE staining proved an improved fat integrity while a gradually decreased vacuoles and fibrosis. CD31 immunohistochemical staining showed that the number of neo-vascularisation in groups E and F were significantly higher than those in groups A-D (P<0.05). Perilipin immunofluorescence staining showed that with the increase of HAPA volume ratio, the number of living adipocytes increased gradually, and more new adipocytes could be seen in the field of vision.ConclusionAs the volume ratio of HAPA gradually increased, the survival of transplanted adipose tissue also increased, but the volume retention rate decreased gradually. 30%HAPA was considered the relative optimal volume ratio for its superior adipose tissue survival and volume retation rate.