Platelet lysate promotes the expansion of Tregulatory cells that favours in vitro wound healing by increasing keratinocyte migration and fibroblast production of extracellular matrix components.

Abstract

Platelet lysate (PL) contains a cocktail of growth factors and cytokines that promote tissue repair and regeneration. In vitro studies have shown that PL may affect the reparative function of keratinocytes and fibroblasts, but little is known about the effect of PL on immune cells involved in wound healing. To analyse the effects of PL on Tcells involved in the wound repair process. The effect of PL on Tcell proliferation, activation, and cytokine production was measured by ELISA and cytofluorometry and regulatory function based on cytofluorometry and Foxp3 RNA expression. Using an in vitro model of wound healing, we investigated the effect of PL-treated Tcells on fibroblast proliferation and production of fibronectin and type-1 collagen as well as keratinocyte migration. PL induced Tlymphocyte proliferation and CD69 expression, and promoted a transient upregulation of IFN-γ and TNF-α. However, later on, PL enhanced the number of CD25+ Tcells releasing TGF-β and expressing Foxp3 RNA, which was accompanied by a suppression in the level of type 1 cytokines. In the in vitro model, supernatants of PL-treated Tcells positively affected the reparative capacity of human keratinocytes and induced fibroblast proliferation and production of fibronectin and type-1 collagen. These results indicate that PL temporally regulates Tcells during the healing process, enhancing protective cytokines in the early phase, followed by a prominent expansion of TGF-β+ Tregulatory cells that promote tissue regeneration and dampen the inflammatory response to prevent excessive tissue damage.