Effect of growth factors on the characteristics of cells associated with equine wound healing and sarcoid formation.

Wound healing in equidae is delayed and more complicated than in other species. These complications arise from a condition known as exuberant granulation tissue formation. The lower limb of the horse is frequently slower to heal than other parts of the body and has a particular tendency to produce excess (exuberant) granulation tissue. Sarcoids are tumor-like lesions of the skin which often appear at the site of wounds. This study compared the growth characteristics of the sarcoid and granulation tissue-derived cells with normal dermal fibroblasts grown from primary cell cultures. All three cell types had distinct morphologic differences. Growth rate studies showed that the sarcoid and granulation tissue-derived cells grew at a slower rate than the normal cells. The addition of the growth factors epidermal growth factor, acidic fibroblast growth factor, and basic fibroblast growth factor selectively stimulated the replication of normal and sarcoid-derived cells but inhibited the growth of granulation tissue-derived cells. In contrast, transforming growth factor-beta was not preferentially inhibitory for the granulation tissue-derived cells. The addition of growth factors to the medium also produced distinct alterations in the morphology of the cells.