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G Gabbiani

Publications and source records attributed to G Gabbiani.

319 records · Page 18Linked to original sources
PubMedDate not supplied

Covering by a flap induces apoptosis of granulation tissue myofibroblasts and vascular cells.

It has recently been shown that during the healing of an open wound, apoptosis mediates the decrease in cellularity during the transition between granulation tissue and scar. Because reduced contraction and a decrease in the number of fibroblastic cells have been described in wounds covered with a successful skin graft, we hypothesized that apoptosis could be responsible for these phenomena. Using in situ labeling of fragmented DNA, immunohistochemistry for alpha-smooth muscle actin, and electron microscopy, we have studied in rats the evolution of 10-day-old wound tissue covered with a total skin flap (containing epidermis, dermis, and the cutaneous muscle). In 10-day-old wound tissue, few apoptotic vascular cells and rare apoptotic myofibroblasts were present; the number of apoptotic cells increased slightly 72 hours later. In wounds covered with total skin flaps, the number of apoptotic vascular and myofibroblastic cells increased drastically 6 hours after flap application with a maximum at 24 and 48 hours, respectively. A decrease of apoptotic cell number was noted at 72 hours; at this time, the size of the granulation tissue was greatly reduced and showed extracellular matrix remodeling. Total flaps were more efficient in the induction of granulation tissue cell apoptosis compared with dermo-epidermal flaps. Moreover, the control application of full-thickness skin autografts, which were not viable 7 days later, did not induce apoptosis 24 hours after implantation. Our results indicate that covering granulation tissue with a skin flap results in a massive apoptotic process, possibly by means of a (some) locally released substance(s).

Journal Article↗
PubMedDate not supplied

Subcutaneous tissue fibroblasts transfected with muscle and nonmuscle actins: A good in vitro model to study fibroblastic cell plasticity.

Cultured fibroblasts develop several biochemical and morphological properties of smooth muscle cells, particularly the expression of alpha-smooth muscle actin, the actin isoform typical of vascular smooth muscle cells. They resemble modified fibroblasts or myofibroblasts observed in granulation tissue during wound repair and in fibrotic situations. We have analysed by immunolabeling the fate of exogenous epitope-tagged actin isoforms by transfection of the corresponding cDNAs into fibroblasts cultured from rat subcutaneous tissue. Tagged muscle actins were efficiently integrated into stress fibers and did not produce obvious changes in cell shape of transfected cells. Transfected nonmuscle actins in contrast changed the morphology and were not or poorly incorporated into stress fibers. These cultured subcutaneous fibroblasts behave similarly to smooth muscle cells when transfected with the same actin encoding cDNAs, indicating another common characteristic of these two cell types in sorting and targeting actin isoforms. Subcutaneous fibroblasts transfected with muscle and nonmuscle actin isoforms provide a good in vitro model to analyze the intracellular sorting of isoactins and to improve our knowledge of myofibroblast characterization and differentiation during tissue repair as well as to understand the relationships between modifications of actin cytoskeleton, adhesion and extracellular matrix proteins.

Actins↗
PubMedDate not supplied

Modulation of actin isoform expression in cultured arterial smooth muscle cells by heparin and culture conditions.

Heparin inhibits arterial smooth muscle cell (SMC) proliferation in vivo and in vitro; moreover, it reinduces the expression of alpha-smooth muscle (SM) actin (an accepted marker of SMC differentiation) in SMCs of the intimal thickening that develops after experimentally induced endothelial lesions. We have investigated the effect of heparin on the proliferation and actin isoform expression in cultured rat SMCs. In the presence of 10% fetal calf serum (FCS), heparin-treated primary and passage 5 SMCs showed a decrease of proliferation and an increase of alpha-SM actin (measured by Western blots or two-dimensional gel electrophoresis) compared with untreated SMCs. When SMCs were cultured in the presence of 10% plasma-derived serum, no proliferation occurred and heparin did not modify alpha-SM actin expression. This suggests that the action of heparin is related to its antiproliferative activity. SMCs cultured in the presence of 10% FCS plus heparin had the same level of proliferation as SMCs cultured in 5% FCS but had a higher content of alpha-SM actin. SMCs cultured in 20% rat whole-blood serum had a proliferation similar to that observed in SMCs cultured in 10% FCS but had a higher content of alpha-SM actin. Moreover, in SMCs cultured in 20% whole-blood serum, heparin inhibited SMC proliferation but did not modify alpha-SM actin expression. Thus, the action of heparin on alpha-SM actin expression appears to be partially independent of proliferation and is related to culture conditions. The proportion of alpha-SM actin mRNA, as measured by Northern blots with an alpha-SM actin mRNA-specific probe, was increased by heparin compared with cells cultured in 10% FCS; this suggests that heparin acts at the transcriptional or posttranscriptional level. Our results show that heparin acts not only on SMC proliferation but also on SMC differentiation; further investigation along these lines may help in the understanding of the mechanisms of SMC adaptation during normal and pathological conditions.

Actins↗
PubMedDate not supplied

Cytodifferentiation and expression of alpha-smooth muscle actin mRNA and protein during primary culture of aortic smooth muscle cells. Correlation with cell density and proliferative state.

To investigate a possible correlation between cytodifferentiation, proliferation, and actin expression, smooth muscle cells from the 9-week-old rabbit aortic media were enzyme-dispersed into single cells and were plated in primary culture at different initial seeding densities. The volume fraction of myofilaments (Vv myo) in cells seeded moderately densely fell from 39.5% +/- 1.2% in the intact aortic media to 11.5% +/- 1.6% on Day 5, one day before the onset of logarithmic growth. The Vv myo remained low over the next 3 days, then began to rise as the density of cells increased, returning almost to the original levels after confluency and 1.84 cumulative population doublings (CPD). The expression of alpha-smooth muscle actin mRNA followed a similar time course of change, falling from 84.7% +/- 1.2% of total actin mRNA in freshly isolated cells to 54.0% +/- 6.5% on Day 5, returning to 87.5% +/- 0.5% after confluency. In these cultures, the alpha-smooth muscle actin protein content was 93.7% +/- 2.9% of total actin in freshly isolated cells, 68.7% +/- 3.1% on Day 5, and 73.3% +/- 2.5% 3 days after confluency. In densely seeded cultures, the Vv myo and expression of alpha-smooth muscle actin mRNA fell only slightly on Day 5 and rose to original levels upon confluency after 0.33 CPD. However, at the protein level, alpha-smooth muscle actin decreased on Day 5 and remained low on Day 12. The Vv myo, alpha-smooth muscle actin mRNA, and actin protein of sparsely seeded cells fell on Day 5 and then remained low throughout the culture period, including 5 days after confluency (Day 24), when the cells had undergone 5.37 CPD. Cells that were maintained subconfluent but quiescent on Day 7 in culture had the same low Vv myo, low alpha-actin mRNA expression, and low alpha-actin protein content as actively proliferating cells. The results show that Vv myo and alpha-smooth muscle actin mRNA undergo parallel changes during primary culture according to seeding density, but not to replication, and that alpha-smooth muscle actin protein decreases in culture then remains low irrespective of culture conditions.

Actins↗
PubMedDate not supplied

Cell biology of smooth muscle in culture: implications for atherogenesis.

Smooth muscle cells are one of the most important, if not the most important component of atheromatous plaque. Smooth muscle cells from developing and regenerating arteries, as well as atheromatous plaques, show similar morphological and biochemical characteristics which differ from adult tissue. During primary culture, adult smooth muscle cells alter their morphology to resemble those of the developing, regenerating and atheromatous material. We propose that primary cell culture of smooth muscle cells provides a model for the study of smooth muscle cell changes during atheroma formation.

Animals↗
PubMedDate not supplied

Desmosomes and gap-junctions in various epidermoid preneoplastic and neoplastic lesions of the cervix uteri.

The distribution of desmosomes and of gap-junctions was studied by morphometric means, at the electron microscopic level, in the following lesions of the uterine cervix: metaplasia, moderate and severe dysplasia, carcinoma in situ and invasive epidermoid carcinoma. The results were compared with normal exocervical epithelium. The proportion of the cell surface occupied by gap-junctions was decreased in all lesions; gap-junctions were statistically absent from moderate dysplasia and more advanced lesions. The number of desmosomes decreased gradually from metaplasia to invasive carcinoma, with each stage forming a discrete group. This gradual loss of intercellular structures with increasing degrees of malignancy might express dedifferentiation and could be associated with increasing cellular autonomy.

Adult↗
PubMedDate not supplied

Relationship between alpha-smooth muscle actin expression and fibrotic changes in human kidney.

The alpha-smooth muscle (alpha-SM) actin isoform is expressed normally by vascular SM cells and by stromal fibroblastic cells in pathological conditions leading to fibrosis. In order to investigate the relation between kidney fibrosis and alpha-SM actin expression, we studied 51 renal biopsies from 45 patients: 30 with various forms of glomerulonephritis; 1 with acute tubular necrosis; 1 with acute interstitial nephritis, and 13 renal transplant recipients. The presence of alpha-SM actin was examined by using anti-alpha SM-1, a mouse monoclonal antibody (IgG2 alpha) specific for alpha-SM actin. alpha-SM actin scores were estimated semiquantitatively, as were glomerulosclerosis and interstitial fibrosis. In acute tubular necrosis and in well-functioning grafts, alpha-SM actin expression was limited to vascular SM cells. In glomerular diseases, alpha-SM actin expression was upregulated in mesangial area in 25 of 36 biopsies, and even more frequently in the periglomerular and peritubular interstitium (34 of 36 cases, chi 2 = 7.6, P < 0.01). Whereas glomerular alpha-SM actin expression seemed to decrease as glomerulosclerosis progressed, there was a positive correlation between interstitial alpha-SM actin scores and the degree of interstitial fibrosis. Similarly, interstitial alpha-SM actin expression was found in acutely or chronically rejected kidneys, but not in well-functioning grafts. We conclude that upregulation of alpha-SM actin in the glomerulus indicates mesangial cell activation and is not always correlated with the degree of glomerulosclerosis. In contrast, interstitial upregulation of alpha-SM actin which indicates myofibroblast activation is correlated with the degree of interstitial fibrosis.

Actins↗