α-Synuclein concentration increases over time in plasma supernatant of single donor platelets.

Abstract

In platelets, α-synuclein is important in calcium-dependent granule release. Notably, cells release α-synuclein in setting of cell damage or death. Therefore, we investigated α-synuclein levels in plasma of single donor platelet (SDP) units during storage. Aliquots were obtained from same SDP units for 7days from day of donation. Additionally, randomly sampled SDP units at same storage time points were also assayed by enzyme-linked immunosorbent assay. α-Synuclein in SDP plasma increased continuously over time at each assayed time point. Significant increases were measured on day 3 (11.7±9.6ng/mL, P=0.025), day 5 (15.3±5.9ng/mL, P=0.002), and highest on day 7 (23.7±5.6ng/mL, P<0.0001) compared to day 0 (1.1±0.8ng/mL). Similar significant results were obtained in randomly sampled SDP units at same corresponding time points. Flow cytometry showed that platelets had strong expression of α-synuclein and lacked expression of other synucleins. Increases of α-synuclein during SDP storage is a steady and continuous process that increases with time. Our findings indicate that α-synuclein may represent a biomarker of platelet biological state during storage. Further research will be needed to determine how α-synuclein increases correlate with platelets' function.