Y. Gaubin et al., MODULATION BY HYPERGRAVITY OF EXTRACELLULAR-MATRIX MACROMOLECULES IN IN-VITRO HUMAN DERMAL FIBROBLASTS, Biochimica et biophysica acta (G). General subjects, 1245(2), 1995, pp. 173-180
In vitro human dermal fibroblasts were submitted to normal gravity (1
g) or to chronic hypergravity (20 g) over a period of 8 days. Changes
in organization of extracellular matrix molecules were seen by indirec
t immunofluorescence. In the fibronectin layer, bundles of fibrils wer
e gathered together leading to a disorganisation of the normal paralle
l pattern of fibers seen in control cultures. Type I collagen fibrils
appeared with wooly outlines in controls whereas thick fibers were clo
sely packed in 20-g cultures. A moderate increase of type III collagen
fibril density was observed. No elastic fibers were seen in control o
r in 20-g cultures. In the culture medium, the release of soluble elas
tin (ELISA) and type I and III collagens (RIA) was undisturbed. Assays
of enzymes involved in the remodeling of extracellular matrix showed
an increase of cellular elastase activity (10%) and a decrease of the
spontaneously active collagenase. Nevertheless, the total collagenase
activity, (activated by trypsin), was increased by up to 30%. These da
ta show a significant rise of the latent collagenase activity and sugg
est that release of the tissue inhibitor of metalloproteinase (TIMP1)
was enhanced by hypergravity.