Extracorporeal Photopheresis Stimulates Tissue Repair after Transplantation

Extracorporeal photopheresis (ECP) is a safe and effective therapy with long-established indications in treating T cell-mediated immune diseases, including steroid refractory graft-versus-host disease and chronic rejection after heart or lung transplantation. The ECP procedure involves collecting autologous peripheral blood leucocytes that are driven into apoptosis before being reinfused intravenously. ECP acts primarily through in situ exposure of recipient dendritic cells and macrophages to apoptotic cells, which then suppress inflammation, promote specific regulatory T-cell responses, and retard fibrosis. Here, we explore the idea that macrophages exposed to apoptotic cell components from photopheresates acquire a tissue-reparative capacity that could be exploited therapeutically. Specifically, we consider innovative applications of ECP in resolving tissue injury after liver transplantation.