Effects of aloe extracts on human normal and tumor cells in vitro

Fractions of leaf extracts from 2 local types, labeledAloe vera (subsequently identified asAloe barbadensis Mill, andA. saponaria Haw.), were prepared by differential centrifugation and tested by in vitro assays for the presence of lectinlike activities and for effects on the attachment and growth of human normal and tumor cells. Fractions of extracts of fresh leaves and commercially “stabilized”Aloe vera gel had high levels of lectin-like substances measured by immunodiffusion and hemagglutination assays. Substances in fluid fractions from both fresh leaf sources were found to markedly promote attachment and growth of human normal, but not tumor, cells and to enhance healing of wounded cell monolayers. In contrast, fractions of “stabilized”Aloe vera gel were equally cytotoxic for human normal and tumor cells in vitro. Results from cell assays suggested that the observed growth promotion and wound healing effects of aloe substances in vitro may be analogous to what has been observed in vivo during healing of wounds and burns.