POSITIVE INFLUENCE OF TETRACYCLINE ON HUMAN FETAL KIDNEY IN SERUM-FREE ORGAN-CULTURE

Human fetal kidney explants can be maintained during 5 days in Leibovi tz's L15, a basic serum-free medium. Because culture conditions are mi nimal for growth and differentiation, DNA synthesis drastically decrea ses during the first 48 h, but stabilizes thereafter. The addition of insulin plus transferrin significantly restores this important cellula r function in kidneys of fetuses younger than 16 wk. However, renal ex plants from older fetuses are more difficult to culture: they respond less to growth factors and are more prone to necrosis. The objective o f this study was to verify the influence of tetracycline, an antibioti c with anti-collagenase potential, on cultured kidney explants aged 17 to 20 wk. The addition of 20 mu g/ml tetracycline did not influence D NA synthesis nor the effectiveness of insulin plus transferrin on cell proliferation. Nor did it change the activities of alkaline phosphata se and gamma-glutamyltransferase, two enzymic markers of brush border differentiation. After 5 days in L15 alone, explants often showed necr osis and an important reduction in both weight and volume. Insulin plu s transferrin significantly restored these parameters to control value s observed at Day 0, but evidence of necrosis was still present. Tetra cycline alone markedly reduced explant necrosis resulting in a signifi cant increase in weight and volume. The effectiveness of insulin plus transferrin on explant morphometry was not improved when tetracycline was added as third factor. These results indicate that insulin plus tr ansferrin restores explant mass through cell proliferation, whereas te tracycline does so possibly through a reduction in extracellular matri x degradation. The two effects are not additive in cultured mid-term f etal kidneys.