Effects of methotrexate in vitro on epidermal cell proliferation

Abstract

Epidermal cell migratory activity and epidermal cell proliferation are clearly dissociable in pig skin explant culture. Epidermal cell migration requires a non-dialyzable, 65,000 MW factor which is destroyed at 100.degree. C but is stable at 80.degree. C for at least 30 min. In the presence of dialyzed serum or heated serum (80.degree. C for 30 min) or DNA synthesis inhibitors (methotrexate or hydroxyurea), cells will migrate from the explant but will not proliferate. At least 2 factors are required for normal proliferation under these restricted conditions.sbd.an adequate supply of DNA precursors, i.e., nucleosides, and a heat labile (80.degree. C) non-dialyzable serum component. Methotrexate in concentrations of 1.0 .mu.g/ml or greater added to cultures in normal fetal calf serum significantly inhibited mitoses; however, when added to serum dialyzed to remove thymidine, mitotic inhibition occurred at a concentration of 0.1 .mu.g/ml of methotrexate and when added to dialyzed serum and kept in dialyzed serum, inhibition occurred with 0.01 .mu.g/ml of methotrexate. Methotrexate did not inhibit outgrowth. Hydroxyurea also inhibited mitoses but did not affect outgrowth.