Expression Of ECM Proteins Research Articles

The effects of types of degradable polymers on porcine chondrocyte adhesion, proliferation and gene expression

Understanding how a specific biomaterial may influence chondrocyte adhesion, proliferation and gene expression is important in cartilage tissue engineering. In this study several biodegradable polymers that are commonly used in tissue engineering were evaluated with respect to their influence on chondrocyte attachment, proliferation and gene expression. Primary cultures of porcine chondrocytes were performed in films made of poly-L-lactic acid (PLLA), poly-D,L-lactic acid (PDLLA), poly-(lactide-co-glycolide) (PLGA), or polycaprolactone (PCL). Chondrocytes adhered to PDLLA or PLGA after 1-day incubation better than to PLLA or PCL. After 7 or 14 day culture, the cell numbers on PDLLA or PLGA was still higher than PLLA or PCL. The results suggested that cell attachment and growth might depend on degradation rate of biodegradable polymers. Along with the fact that PDLLA or PLGA supported expression of chondrocyte specific genes more than PLLA or PCL, the former two materials seemed to be more suitable for cartilage tissue engineering than the latter ones. Besides, we found that chondrocyte phenotype prior to seeding was important in the expression of ECM proteins.

Eosinophils in repair and remodelling

SummarySeveral studies in man suggest a role for the eosinophil in repair in remodelling. Skin biopsies taken at time intervals after allergen injection into human skin indicate that the formation of myofibroblast‐like cells and activation of fibroblasts, as shown by tenascin and procollagen‐1 production, may be partly under the control of infiltrating TGF‐β1+/IL‐13+ eosinophils. Studies involving the infusion of an anti‐IL‐5 monoclonal antibody to atopic subjects indicate that eosinophils are unlikely to be essential for the redness, swelling and induration characteristic of late‐phase allergic response but may play a role in repair/remodelling processes as shown by inhibition of tenascin deposition. Selective reduction of eosinophils by anti‐IL‐5 was also associated with a significant reduction in the up‐regulated expression of ECM proteins in the reticular basement membrane of asthmatics. Furthermore, this reduction in the expression of matrix proteins occurred over a relatively short time period and despite only partial eosinophil depletion. Taken together these data provide direct evidence of a causal association between eosinophils and ECM protein deposition in mild atopic asthma.

All-trans retinoic acid regulates proliferation, migration, differentiation, and extracellular matrix turnover of human arterial smooth muscle cells.

The vitamin-A derivative all-trans retinoic acid (atRA) is a potent regulator of cell growth, differentiation, and matrix formation of various cell types and plays an important role in embryogenesis. However, sparse data are available about its effects on human vessel diseases. Thus, we studied the effects of atRA on human arterial smooth muscle cell (haSMC) and endothelial cell (haEC) proliferation, migration, differentiation and extracellular matrix (ECM) turnover in mono- and transfilter cocultures. Effects of atRA on human arterial cells in monocultures were determined using cell counting assays, BrdU-ELISA and MTT-tests. In transfilter cocultures haSMC-growth was studied under the stimulatory effect of proliferating haEC. Using Northern blot analysis, effects of atRA on mRNA expression of ECM-proteins were examined while protein expression and activity of matrix metalloproteinases were determined by Western blotting and zymography. atRA caused a dose dependent inhibition of haSMC-growth in monocultures (IC(50) at 0.022 microM) whereas haEC-growth was inhibited less potently (IC(50) at 97 microM). In addition, proliferation and migration of haSMC through a porous membrane were inhibited dose dependently by micromolar atRA-doses after non-stop and single dose application of atRA on the endothelial side of the complex transfilter coculture system. Immunostainings and Northern blotting demonstrated an enhanced alpha-smooth muscle actin and heavy chain myosin expression in haSMC after atRA-treatment. Whereas mRNA-expression of the glycoproteins thrombospondin-1 and fibronectin were decreased, collagen-1 mRNA expression was even slightly stimulated. Transcription of biglycan and TGF-beta1 were not influenced in a specific manner. Finally, protein expression and activity of the matrix metalloproteinases MMP-2 and MMP-9 were inhibited significantly by atRA. atRA was found to be a potent inhibitor of both haSMC-proliferation and -migration, even in coculture with haEC releasing growth factors. In addition, redifferentiation, ECM synthesis and ECM degradation were regulated by atRA which also influence haSMC migration and intima formation. Thus, atRA-treatment seems to be a promising strategy for the inhibition of processes involved both in atherosclerosis and restenosis.