COLLAGEN-SYNTHESIS IN EXPLANT CULTURES OF NORMAL AND CCL4-TREATED MOUSE-LIVER

Acute liver damage was induced in mice by oral administration of a single dose of CCl4. The activity of prolyl hydroxylase and the incorporation of [2,3-3H]proline into collagen and noncollagen proteins were significantly increased 3 days after CCl4 administration when compared to controls. Collagen synthesis, measured as the percentage of total protein synthesis in primary organ cultures, was also significantly increased at this time. Explant cultures of damaged liver fragments were characterized by a rapid outgrowth of cells, while normal liver explants grew more slowly as indicated quantitatively by cell number present and radioactive thymidine incorporation into DNA. The rate of incorporation of radioactive proline into both collagen and noncollagen proteins measured at different intervals in the explant cultures increased in parallel with the rate of outgrowth of the cells from the tissue fragments. The amount of collagen produced per cell by cultures of injured liver was elevated at all time periods with a maximum 10-fold elevation observed after 11 days in culture. Maximum collagen production as a percentage of total protein synthesis was found to be associated with the early stages of culture growth where the proportion of collagen made increased in the initial phases of outgrowth and subsequently decreased despite the continuous proliferation of the cultures. This relative rate of collagen synthesis was significantly higher in the explant cultures of damaged liver tissue compared to the controls for at least 11 days in culture. This study indicates that the growth in culture of cells committed to collagen production is stimulated by acute liver injury. This response may be an early marker of the mesenchymal cell reaction to liver injury which eventually leads to liver fibrosis. © 1979 Academic Press, Inc. All rights reserved.