DIFFERENTIAL DISTRIBUTION OF OLIGODEOXYNUCLEOTIDES IN DEVELOPING ORGANS WITH EPITHELIAL-MESENCHYMAL INTERACTIONS

The use of antisense oligodeoxynucleotides (ODNs) to inhibit gene expr ession is a usefull method for determining protein function and has po tential therapeutic applications. However, there is still great variab ility in the successfull application of antisense technology to indivi dual systems. In order to assess the ability of different cell types t o take up ODNs, developing embryonic tissues were cultured in vitro in the presence of fluoresceine labelled, phosphorothioate substituted O DNs. The distribution of ODNs in individual cell populations was assay ed by fluorescent microscopy and the tissue sections were counterstain ed for epithelial basement membrane formation. High intracellular leve ls of ODNs were observed in all mesenchymal cells of the lung, salivar y gland, kidney, ovary and testis. However, a significant decrease in ODN levels was observed with the formation of new epithelium in kidney and gonads, whereas mature epithelial cells in all tissues had no det ecable levels of ODNs. The ability to inhibit gene expression in mesen chymal cells, but not in epithelial cells, was consistent with the dis tribution pattern of labeled ODNs. These results may indicate a genera l resistance of epithelial cells to take up ODNs in culture and bear d irectly on the ability of ODNs to affect gene expression in complex or gans with epithelial components.