Enhanced Expression of Integrin Receptors During Proliferation of Activated Keratinoblasts Prepared for Transplantation as Cell Suspension in Fibrinous Matrix

Abstract

Integrins are principal receptors on animal cells for binding most extracellular matrix proteins, including collagen, fibronectin, and laminin. One integrin function is to transmit mechanical forces by connecting the cytoskeletal network of keratinoblasts/keratinocytes with the exoskeleton of the connective tissue. This function is related to the maintenance of basal keratinoblasts/keratinocytes by preventing terminal differentiation. The keratinoblasts/keratinocytes remain in unrestricted proliferation. Terminal differentiation correlates with downregulation of the integrins [1]. Cell functions like proliferation, differentiation, attachment, spreading, and migration depend on cell-matrix contacts mediated by cell surface receptors including the integrin group. The a ₅ subunit, which is part of the fibronectin receptor a ₅ β ₁, was expressed by defined activated keratinoblasts [2, 3]. Different types of clones [4] develop in the secondary clonal culture of keratinoblasts: clone type mitotic keratinoblast I, II, and III (CTMK I, CTMK II and CTMK III). Changes in the frequencies of the distinct clone types can be observed as a function of the cummulative population doubling level of the heterogeneous populations. For the analysis of the biological changes accompanying cytodif-ferentiation of secondary keratinoblasts in the cell lineage, methods have been developed to enrich the three mitotic keratinoblasts from the heterogeneous mitotic populations.