Effects of amotosalen treatment on human platelet lysate bioactivity

BackgroundClinical application of mesenchymal stromal cells (MSCs) usually requires an in vitro expansion step to reach clinically relevant numbers. In vitro cell expansion necessitates supplementation of basal mammalian cell culture medium with growth factors. To avoid using supplements containing animal substances, human platelet lysates (hPL) produced from expired and pathogen inactivated platelet concentrates can be used in place of fetal bovine serum. Due to lack of experience and global diversity in bacterial detection strategies, most transfusion units are currently not pathogen inactivated. As blood banks are the sole source of platelet concentrates for hPL production, it is important to ensure product safety and standardized production methods. To achieve these aims, we assessed the quality of hPL produced from expired platelet concentrates with pathogen inactivation applied after platelet lysis, as well as its ability to support MSC proliferation and tri-lineage differentiation.\n\nMethodology/principal findingsBone marrow-derived MSCs (BM-MSCs) were expanded and differentiated using hPL derived from pathogen inactivated platelet lysates (hPL-PIPL), with pathogen inactivation applied after lysis of expired platelets. Results were compared to those using hPL produced from conventional expired pathogen inactivated human platelet concentrates (hPL-PIPC), with pathogen inactivation applied after soon after blood donation. hPL-PIPL treatment had lower concentrations of soluble growth factors and cytokines than hPL-PIPC treatment. When used as supplementation in cell culture, BM-MSCs proliferated at a reduced rate, but more consistently, in hPL-PIPL than in hPL-PIPC. The ability to support tri-lineage differentiation was comparable between lysates.\n\nConclusion/significanceThese results suggest that functional hPL can be produced from expired and untreated platelet lysates by applying pathogen inactivation after platelet lysis. When carried out post-expiration, pathogen inactivation can provide a valuable tool to further standardize global hPL production methods, increase the pool of starting material, and meet the future demand for animal-free supplements in human cell culturing.