Reversal of advanced liver fibrosis in rabbits with Schistosomiasis japonica.

Advanced liver fibrosis is generally considered to be irreversible. We studied the reversibility of marked liver fibrosis in rabbits infected with Schistosoma japonicum. We determined liver collagen content, collagen biosynthesis, and collagenase activity using serial biopsy specimens obtained 20, 40, and 60 weeks after infection. Reversibility of this process was investigated in rabbits cured of infection at 21 weeks; control rabbits not cured of infection were also studied. At 20 weeks, liver collagen content was 16-fold greater than normal, with accumulation of collagen types I, III, and V. Synthesis of collagen within fibrotic liver slices was 10-fold greater than normal. Liver collagenolytic activity for a type I substrate was 19-fold greater than normal. After parasitologic cure, a striking morphologic reversal of fibrosis occurred during the subsequent 40 weeks, with the return of liver collagen content to three-fold greater than normal and a 75% decrease in synthetic rates compared with those at 20 weeks (P < 0.01). Collagenolytic activity remained elevated to the same degree noted at 20 weeks. A similar but lesser resolution of fibrosis also occurred in untreated control rabbits, coincident with a spontaneous decrease in new egg deposition known to occur in this model system. We conclude that advanced liver fibrosis in S. japonicum-infected rabbits is slowly reversible after cure or senescence of the infection. A possible mechanism for this reversal is persistently increased collagenolysis as collagen synthesis diminishes.

Histological and biochemical characterization of murine sarcomas.

A mouse fibrosarcoma and rat osteosarcoma were examined histologically and biochemically with regard to collagen content. The fibrosarcoma was composed of undifferentiated mesenchymal cells without distinct fibroblastic characteristics. Collagen production and deposition were consistent with those observed in cultured fibroblasts. Type I and type III collagens were evident as determined by immunofluorescence staining and biochemical analysis. The osteosarcoma appeared similar to bone with regard to a high content of type I collagen, limited calcification and poor vascularization. While these sarcomas do not histologically resemble their non-transformed counterparts, analysis of their macromolecular composition confirmed the identity of their presumed cell of origin. Similar methodology could be readily applied for identification and classification of human malignant sarcomas.

Effects of procollagen peptides on the translation of type II collagen messenger ribonucleic acid and on collagen biosynthesis in chondrocytes.

Type II procollagen messenger ribonucleic acid (mRNA) was isolated from chick sternum and rat chondrosarcoma cells and translated in a reticulocyte lysate cell-free system. A high molecular weight band was identified as type II procollagen by gel electrophoresis, collagenase digestion, and specific immunoprecipitation. The translation of type II mRNA was specifically inhibited by addition of type I procollagen amino-terminal extension peptide. When this peptide was added to the media of cultured fetal calf chondrocytes, chick sternal chondrocytes, or chick tendon fibroblasts, no inhibition of collagen synthesis was evident. These data suggest a general regulation of collagen biosynthesis by these peptides in the cell-free translation system. However, as indicated by the cell culture experiments, cellular characteristics and evolutionary divergence of animal species seem to restrict the effect of the peptides.

Hormone-dependent growth of a rat chondrosarcoma in vivo.

The importance of various hormonal factors in the growth of a transplantable chondrosarcoma has been studied in vivo. Tumor growth was reduced by 95% in adrenalectomized or hypophysectomized rats as compared to normal animals. The number of tumors developing in either adrenalectomized or hypophysectomized rats was reduced more in male than in female rats. However, ovariectomy or orchiectomy did not alter the growth of the tumor. The inhibition of tumor growth in adrenalectomized and hypophysectomized animals was only observed after the first 10 days following inoculation. Cortisone (4-pregnen-17 alpha,21-diol-3,11,20-trione) administration fully restored tumor growth in adrenalectomized animals while adrenocorticotropic hormone or growth hormone were only partially effective in supporting tumor growth in hypophysectomized animals. High-affinity glucocorticoid receptors (7 to 10S) were present in the cytosls prepared from the tumor cells and were found to be increased in tumors from adrenalectomized animals. These results indicate that the growth of this chondrosarcoma is strongly dependent upon endocrine factors of adrenal and pituitary origin.