Activation of rabbit keratinocyte fibronectin receptor function in vivo during wound healing

Freshly isolated rabbit keratinocytes expressed low fibronectin (pFN) receptor function as shown by their poor ability to attach and spread on pFN-coated substrata or to bind and ingest pFN-coated beads. Following in vitro culture of these cells, however, pFN receptor function was activated. The cultured cells appeared to be normal, based on their ability to reepithelialize rapidly full-thickness cutaneous wound beds. Freshly isolated keratinocytes that had low pFN receptor function were autotransplanted onto full-thickness wound beds. Two days after transplantation, keratinocytes recovered from these wounds were observed to express increased pFN receptor function. This activity was maximal in keratinocytes isolated 3 days after transplantation and declined in keratinocytes isolated at later times. By 10 days after transplantation, the transplanted cells had formed a multilayered hyperplastic epidermis and reconstituted their laminin and type IV collagen-containing basement membrane. It is proposed that initiation of pFN receptor function in keratinocytes is a crucial mechanism necessary for them to attach to and migrate through the pFN-rich wound bed comprised of granulation tissue. After reepithelialization is complete, and the basement membrane re-forms, pFN receptor function declines markedly because it is no longer essential to the cells.