Isolation and characterization of a novel type of growth factor derived from serum-free conditioned medium of chicken embryo fibroblasts

Human connective tissue growth factor expressed in Escherichia coli is a non-mitogenic inhibitor of apoptosis

After cloning and sequencing chicken connective tissue growth factor (cCTGF) we showed that in serum-deprived chicken embryo fibroblasts (CEF) the initial decline of cCTGF mRNA was followed by an increase. Human CTGF that was produced as a soluble protein in Escherichia coli by thioredoxin co-expression inhibited serum-deprivation induced apoptosis of CEF at I(50) of approximately 8pM, demonstrating a function of CTGF at concentrations observed in supernatants of fibroblasts. CTGF was neither mitogenic for CEF nor for other cell types. In conclusion CTGF supports very efficiently survival of certain cells without stimulating their cell growth.

Effects of transforming growth factor-beta and platelet-derived growth factor on human gingival fibroblasts grown in serum-containing and serum-free medium

Both transforming growth factor-beta (TGF-beta) and platelet-derived growth factor (PDGF) have been shown to affect cell proliferation in vitro. The hypothesis being tested was that the effects of the 2 cytokines would be modulated by the presence of serum in the medium. Gingival fibroblasts, obtained from periodontally healthy patients, were maintained in primary culture. Dose response experiments were performed for each growth factor in serum-free medium and in medium containing natural or heat-inactivated fetal bovine serum (10% FBS). Changes in cell numbers were quantified by crystal violet staining. The optimal concentrations of the individual factors (10 ng/ml TGF-beta1, 20 ng/ ml PDGF-BB) were then used when the 2 factors were tested in various sequences. In serum-free medium or in medium with 10% natural serum, the response to PDGF-BB was dose-dependent up to 40 ng/ml; however, with 10% heat-inactivated serum, the maximal response was seen at 20 ng/ml. The largest increase in cell numbers was produced by the simultaneous exposure to the two cytokines, rather than a sequential presentation. The findings suggest that the 48-h growth response of human gingival fibroblasts to 10 ng/ml TGF-beta1 or 20 ng/ ml PDGF-BB in serum-free medium was equivalent to growth obtained in medium containing heat-inactivated 10% FBS without added growth factors.