Effect of a lipopolysaccharide from E-coli on the proliferation of fibroblasts and keratinocytes in vitro

Studies previously conducted in our laboratory have shown that an extract from the leaves of Chromolaena odorata is mitogenic for human skin fibroblasts and keratinocytes. However, lipopolysaccharides, sometimes present in plant extracts, can also play a role in cell growth and might have been responsible for or contributed to the mitogenic activity observed. The present study aimed to investigate whether a lipopolysaccharide would have any effect on the proliferation of human fibroblasts and keratinocytes. Cells were seeded in 96-well plates and concentrations from 0.0 to 5.0 mug/mL of lipopolysaccharide in basal or growth medium were added. Cell growth was determined over a period of 10 days using a colorimetric assay. Lipopolysaccharide at concentrations between 0.05 mug/mL and 0.5 mug/mL in the growth medium significantly stimulated fibroblast proliferation after incubation for more than 6 days. In basal medium, more than 8 days of incubation was needed for significant stimulation of growth. Lipopolysaccharide stimulation of keratinocytes was evident at 0.5 mug/mL by day 3 in basal medium and by day 5 in growth medium. Although the lipopolysaccharide did stimulate cell growth it did so only at higher concentrations than were present in our plant extracts and to a lesser degree. Copyright (C) 2002 John Wiley Sons, Ltd.