OBJECTIVETo investigate the effect of storage time on accumulation of platelet-related growth factors in the supernatant of leukoreduced packed red blood cells (LR-pRBC) and on tumor cell proliferation in vitro.

METHODSLR-pRBC were quartered and stored at 2 °C-6 °C. The supernatant of pRBC was obtained by centrifugation with 1 006 × g for 10 min at day 0, 14, 21 and 35 d. The enzyme-linked immunosorbent assay (ELISA) was used to detect the expression of platelet-derived growth factor(PDGF) and vascular endothelial growth factor (VEGF). After HepG2 cells was cultured with the supernatant of LR pRBC at day 0 and day 35 together for 48 hours, methylthiazoliltetracolium (MTT) method was used to measure the proliferation of tumor cells in vitro.

RESULTSThe concentrations of 2 cytokines were still increased with the storage time prolonging. As compared to LR-pRBC at day 0 [611.84 (95%CI, 356.45-867.23) pg/ml], the level of VEGF reached 900.16 (95% CI, 552.26-1248.07) pg/ml (P<0.05). There was a similar tendency in PDGF level with less increment in the supernatant of LR pRBC at day 35 [2.23 (95% CI, 0-5.37) ng/L vs 5.66 (95% CI, 0-12.48), P=0.073], but there was no significant statistical difference. Likewise, in vitro study of HepG2 cell proliferation showed that the LR-pRBC at day 35 promoted more proliferation of tumor cells with OD value 0.40 (95% CI, 0.38-0.42) (P<0.05).

CONCLUSIONThe residual platelets in LR-pRBC were activated, disintegrated and released the dense granules and α-granules which induce the accumulation of VEGF and PDGF. It seemed that the supernatant of LR-pRBC promoted the proliferation of tumor cells in vitro.