otherwise not engaged signaling pathways (Moore et al., 2001). Moreover, the use of FCS is incompatible with donations of cells to humans for therapeutic purposes (Barsotti et al., 2013; Doucet et al., 2005). Due to these concerns, alternative strategies to the use of FCS have been considered.While fully recombinant serum replacements are still a cost issue, human platelet lysate (hPL) could be a valid and ethically justifiable option. Human keratinocyte cells, renal epithelial cells, and various leukemic and solid tumor cell lines can be propagated in hPL (Fazzina et al., 2016;Rauch et al., 2011; Baik et al., 2014; Bernardi et al., 2013). This also holds true for primary human and rodent cells (adipocytes, amniotic fluid stem cells, bone marrow stromal cells, chondrocytes, corneal cells, endothelial cells, keratinocytes, mesenchymal stem cells, monocytes, osteoblasts) (Barsotti et al., 2013; Doucet et al., 2005;Glovinski et al., 2017). These cell types maintain functionality and signaling in various assays, and some reports even show a better cell proliferation in hPL than in FCS (Bernardi et al., 2013;Glovinski et al.,