MINOXIDIL-INDUCED CHANGES IN THE CONTRACTION OF COLLAGEN LATTICES BY HUMAN SKIN FIBROBLASTS

This investigation has studied the effect of minoxidil on the contract ion of hydrated collagen lattices by human dermal fibroblasts. Type I collagen was mixed with a fibroblast suspension and polymerized, and m inoxidil 10 to 800-mu-g/ml (0.05 to 4 mM) was added at the time the la ttices were released. Minoxidil at concentrations from 100 to 600-mu-g /ml inhibited contraction in a dose-dependent manner, whereas 800-mu-g /ml prevented contraction completely, most cells remaining rounded. Co nsiderable inhibition was already evident within 24 hours. Visualizati on of living cells with MTT and cell counts showed that inhibition in the first 48 hours was not due to fibroblast death. Exchange of minoxi dil to normal medium led to a resumption of contraction and a return t o an elongate morphology. Minoxidil at 10-mu-g/ml had no significant e ffect on lattice contraction, whereas at 100-mu-g/ml it slowed contrac tion without affecting proliferation or morphology, as observed under the light microscope. The inhibitory effect of minoxidil should be inv estigated further in relation to the control of contraction of wounds in vivo.