Absence of collagen stimulating factors for L929 cells in granulation tissue extracts

We have attempted to find collagen synthesis stimulating activity in polyvinyl sponge granulation tissue extracts and inflammatory fluid. The cells studied in culture were mouse L929 cells grown in monolayers. A prior study by another group reported such factors to be present in healing wound extracts and in extracts of CHHl3 injured liver. We have been unable to find such stimulating activity for L929 cells in granuloma tissue fluid. In addition we have examined the procedures used by the prior group and have found major problems in their methodology which are discussed below.