The results suggest that lacidipine may have prevented NF-kappaB-mediated adhesion molecule expression by exerting its effects on oxygen-derived free radicals. The results support previous observations that lacidipine may have therapeutic effects in atherosclerosis.

We have studied the phenotypic changes in regenerating smooth muscle (SM) tissue of detrusor muscle after local application of a necrotizing, freeze-thaw injury to the serosal surface of rabbit bladder. Bromo-deoxyuridine (BrdU) incorporation and immunofluorescence studies were performed on bladder cryosections from day 2 up to day 15 after surgery with monoclonal antibodies specific for some cytoskeletal markers [desmin, vimentin, non-muscle (NM) myosin] and for SM-specific proteins (alpha-actin, myosin, and SM22). Four days after lesion, some clls incorporated in regenerating SM bundles are BrdU positive, but all display a phenotypic pattern identical to that of the interstitial, highly proliferating cells, i.e., expression of vimentin. By days 7-15 the differentiation profile of regenerating SM returns to that of uninjured SM tissue (appearance of desmin, SM-type alpha-actin, and SM myosin). A chemical denervation achieved by 6-hydroxydopamine treatment for 2 weeks induces the formation of vimentin/SM alpha-actin/NM myosin/SM22-containing myofibroblasts in the interstitial, fibroblast-like cells of uninjured bladder. In the bladder wall, alteration of reinnervation during the regenerating SM process produces: (1) in the outer region, the activation of vimentin/SM alpha-actin/desmin myofibroblasts in the de novo SM cell bundles; and (2) in the inner region of bladder, including the muscularis mucosae, the formation of proliferating, fully differentiated SM cells peripherally to newly formed SM cell bundles. These findings suggest that: (1) the de novo SM tissue formation in the bladder can occur via incorporation of interstitial cells into growing SM bundles; and (2) the alteration of reinnervation during the regenerating process induces a spatial-specific differentiation of interstitial myofibroblasts in SM cells before SM cell bundling.

In this study we asked whether the well-known atherosclerosis resistance of rats might be reduced with aging. Two groups of young, adult and aged Wistar rats, one of which was kept on a standard, low-cholesterol (CT) diet, and the other one was fed a 2% CT diet for 2 months were enrolled. Potential modifications in the phenotypic profile of aortic smooth muscle (SM) were assessed by SDS-gel electrophoresis, Western blotting and immunofluorescence procedures using a panel of monoclonal antibodies to myosin isoforms, cytoskeletal and extracellular matrix proteins. With development and aging, the expression of 196-kD non-muscle-type myosin heavy-chain isoform (MyHC), the EIIIA fibronectin variant and keratins was downregulated, whereas that of the 204- and 200-kD SM-type MyHC isoforms, SM-type α-actin and desmin did not change. The levels of hypercholesterolemia achieved in this model did not substantially modify the distribution of the downregulated markers, except for the subendothelial grouping of immature SM cells in aged rats. Morphometric measurements indicated a slight increase of medial cross-sectional area accompanied by a decrease in total SM cell number, both with aging and with hypercholesterolemia. In no circumstance was the presence of atherosclerotic lesions histologically detectable. Bromo-deoxyuridine (BrdU) incorporation analysis revealed a marked age-dependent decline in DNA synthesis and the formation of binucleated cells in aged aortas. This pattern was not influenced by hypercholesterolemia, except in aged rats where BrdU-positive SM cells are almost doubled. Our data indicate that aging and hypercholesterolemia cannot affect the phenotypic stability of rat SM cells and confirm that the change from a fully differentiated to an immature state is a general prerequisite to allow the development of atherosclerotic lesions in mammalian species.

In an attempt to identify the growth factors or cytokines involved in the serosal thickening that occurs in rabbit bladder subjected to partial outflow obstruction, the following growth factors--transforming growth factor beta1, platelet-derived growth factor, epidermal growth factor, granulocyte colony-stimulating factor and granulocyte-monocyte colony-stimulating factor--were delivered separately onto the serosal surface of the intact bladder via osmotic minipumps. The proliferative/differentiative cellular response of the rabbit bladder wall was evaluated by bromodeoxyuridine incorporation and immunofluorescence staining with a panel of monoclonal antibodies to cytoskeletal proteins (desmin, vimentin, keratins 8 and 18 and non-muscle myosin) and to smooth muscle (alpha-actin, myosin and SM22) proteins. Administration of the transforming growth factor, but not of the other growth factors/cytokines, was effective in inducing serosal thickening. Accumulating cells in this tissue were identified as myofibroblasts, i.e. cells showing a mixed fibroblast-smooth muscle cell differentiation profile. The phenotypic pattern of myofibroblasts changed in a time-dependent manner: 21 days after the growth factor delivery, small bundles of smooth muscle cells were found admixed with myofibroblasts, as occurs in the obstructed bladder. These 'ectopic' muscle structures displayed a variable proliferating activity and expressed an immature smooth muscle cell phenotype. The complete cellular conversion to smooth muscle cells was not achieved if transforming growth factor beta1 was delivered to fibroblasts of subcutaneous tissue. These findings suggest a tissue-specific role for this growth factor in the cellular conversion from myofibroblast to smooth muscle cells.