A new procedure is introduced for the isolation of connective tissue fibers, called biomatrix, containing a significant portion of the extracellular matrix (basement membrane components and components of the ground substance) . Biomatrix isolated from normal rat liver contains >90% of the tissue's collagens and all of the known collagen types, including types I and III and basement membrane collagens. The purified collagenous fibers are associated with noncollagenous acidic proteins (including fibronectins and possibly small amounts of glycosaminoglycans) . Procedures are also described for preparing tissue culture substrates with these fibers by either smearing tissue culture dishes with frozen sections or by shredding the biomatrix into small fibrils with a homogenizer. The biomatrix as a substrate has a remarkable ability to sustain normal rat hepatocytes long-term in culture. The hepatocytes, which on tissue culture plastic or on type I collagen gels do not survive more than a few weeks, have been maintained for more than 5 mo in vitro when cultured on biomatrix. These cells cultured on rat liver biomatrix show increased attachment and survival efficiencies, longterm survival (months), and retention of some hepatocyte-specific functions.Despite numerous advances in cell culture procedures (2, 3,14,16,18,24,35), the culture of differentiated epithelial cells, particularly from normal tissues, has remained especially difficult. We have proposed that the shortcomings of cell culture techniques are primarily that cells are isolated from the extracellular matrix and from association with other cell types with which they may be interdependent (30). Culture methods, such as organ culture or the culture oftissue fragments, which retain tissue architecture, preserve the differentiative state of the cells, whereas clonal cell cultures usually undergo a dedifferentiative process (16,40). Thus, to culture differentiated cells it seems logical to ascertain the critical variables of the tissue matrix and to evolve culture procedures dependent upon them.In a previous paper, we presented techniques that we refer to as "socio-cell culture techniques" (30) and that are, in essence, attempts to simulate some of the cell-cell relationships of the tissue matrix relevant to epithelial cells . The techniques we described involve the culturing of epithelial cells on substrates of reconstituted basement membrane and in medium THE JOURNAL OF CELL BIOLOGY " VOLUME 87 OCTOBER 1980 255-263 © The Rockefeller University Press -0021-9525/80/10/0255/09 $1 .00 supplemented with hormones, serum, and with conditioned medium from feeder layers of primary cultures of fibroblasts . In this article, we present new techniques that have superseded the earlier ones. They include the isolation of connective tissue fibers called biomatrix, representing a significant portion ofthe in vivo extracellular matrix (basement membranes and ground substance), and techniques using these fibers as substrates for cultures of differentiated cells . Our lon...

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Throughout life, bone tissue undergoes a continuous process of resorption and formation. Melatonin, with its antioxidant properties and its ability to detoxify free radicals, as suggested by Conconi et al. (2000) may interfere in the osteoclast function and thereby inhibit bone resorption, as suggested by Schroeder et al. (1981). Inhibition of bone resorption may be enhanced by a reaction of indoleamine in osteoclastogenesis. That it has been observed melatonin, at pharmacological doses, decrease bone mass resorption by suppressing through down regulation of the RANK-L, as suggested by Penarrocha Diago et al. (2005) and Steflik et al. (1994). These data point an osteogenic effect towards that may be of melatonin of clinical importance, as it could be used as a therapeutic agent in situations in which would be advantageous bone formation, such as in the treatment of fractures or osteoporosis or their use as, a bioactive surface on implant as suggested by Lissoni et al. (1991).

Adult rat hepatocytes efficiently attach to intact connective tissue fibers prepared from normal rat liver; this material has been given the name of "biomatrix". The cells remain alive and differentiated for at least 4 months in culture. The liver biomatrix contains both collagen and noncollagenous glycoproteins. Heretofore, the functions of the different components of the biomatrix in facilitating cell adhesion and promoting survival and differentiation of rat hepatocytes have not been investigated. We now report on an aggregate of glycoproteins which were with dilute acetic acid from liver biomatrix and which facilitate hepatocyte adhesion to plastic dishes and collagen. One protein in the extract, with a molecular weight larger than 300,000, was selectively immunoprecipitated with an antibody prepared against the extract and immunoadsorbed to glutaraldehyde-cross-linked rat serum. The antibody did not cross-react with cold-insoluble globulin and selectively inhibited cell attachment. The protein of the molecular weight of 300,000 appears to be specific for liver, since similar extracts prepared from rat lung, kidney, and heart biomatrices did not cross-react with the antibody. Furthermore, the latter extracts did not facilitate cell attachment above values obtained with plain culture dishes. The results suggest that glycoproteins in the biomatrix, which are antigenically distinct from fibronectin, can mediate attachment of rat hepatocytes to plastic dishes and collagen.