Characteristics of an autologous leukocyte and platelet-rich fibrin patch intended for the treatment of recalcitrant wounds

We have investigated the physical, biochemical, and cellular properties of an autologous leukocyte and platelet‐rich fibrin patch. This was generated in an automated device from a sample of a patient's blood at the point of care. Using microscopy, cell counting, enzyme‐linked immunosorbent assay, antibody arrays, and cell culture assays, we show that the patch is a three‐layered membrane comprising a fibrin sheet, a layer of platelets, and a layer of leukocytes. Mean recovery of platelets from the donated blood was 98% (±95%CI 0.8%). Mean levels of platelet‐derived growth factor AB, human transforming growth factor beta 1, and vascular endothelial growth factor extracted from the patch were determined as 127 ng (±95% CI 20), 92 ng (±95%CI 17), and 1.35 ng (±95%CI 0.37), respectively. We showed a continued release of PDGF‐AB over several days, the rate of which was increased by the addition of chronic wound fluid. By comparison with traditional platelet‐rich plasma, differences in immune components were found. The relevance of these findings was assessed by showing a mitogenic and migratory effect on cultured human dermal fibroblasts. Further, we showed that fibrocytes, a cell type important for acute wound healing, could be grown from the patch. The relevance of these findings in relation to the use of the patch for treating recalcitrant wounds is discussed.