Signal perception of fibroblasts for directional migration to platelet-derived growth factor in Boyden-type chambers.

Fibroblast chemotaxis has usually been determined in Boyden-type chambers with polycarbonate filters, assuming that a stable concentration gradient of the attractant develops that causes directional migration of the cells. This view has been repeatedly challenged, and development of such gradients in vivo is unlikely. The present experiments were designed to test if a stable concentration gradient was required for normal dermal fibroblasts to migrate toward platelet-derived growth factor. It was found that a brief pulse of the attractant was required and sufficient to induce chemotaxis. The pulse had to contain a specific concentration of attractant and was ineffective when not unilateral. The observed effects could not be attributed to induction of random migration or migration on a mediator-coated surface. It is not clear which machinery is regulating this cellular behaviour, but it is suggested that cells may migrate in vivo by similar mechanisms, because the establishment of stable concentration gradients of attractants in tissues is deemed unlikely.