Comparison of 7-Day Storage of Buffy-Coat Derived Platelet Concentrates in an Osmotically Balanced, Interface Stabilizing Platelet Storage Solution and in Plasma.

The use of platelet additive solutions (PAS) for the storage of buffy-coat derived platelet concentrates (PC) could conserve plasma resources and reduce post-transfusion reactions. However, PASs are difficult to handle in a production environment where their relative low viscosity produces an unstable interface between the platelet rich plasma and the red cell pellet. In the current study, a comparison is drawn between buffy-coat derived PCs (4 buffy-coats per pool) stored over 7 days either in plasma or in a novel Viscous PAS that contains 26 % plasma as a by-product of the buffy-coat pooling process. The increased viscosity (1.18 cp at 37°C) of the PAS results in a stable interface during processing. Similar, though more consistent platelet recoveries from buffy-coat pools (BCP) are achieved by the Viscous PAS (77.0 ± 2.6%) as compared to plasma (73.7 ± 5.9 %). These are significantly higher (p<0.05) than recoveries using conventional PASs (64.5 ± 2.1 %). On day 7, platelet concentration, mean platelet volume (MPV), and soluble protein concentration in PCs stored using Viscous PAS (782 ± 87 x 10⁹ cells/L, 9.1 ± 0.5fL, 15.0 ± 1.6 mg/L, respectively) and plasma (840 ± 104 x 10⁹ cells/L, 9.0 ± 0.7fL, 56.09 ± 9.2 mg/L, respectively) were not significantly different from their corresponding day 1 parameters (837 ± 84 x 10⁹ cells/L, 9.1 ± 0.3 fL, 13.5 ± 0.2 mg/L) respectively for Viscous PAS and (830 ± 73 x 10⁹ cells/L, 8.3 ± 0.5 fL, 56.6 ± 6.5 mg/mL) and for plasma. This indicates that Viscous PAS and plasma maintain platelet integrity to a similar degree during 7-day storage. Both storage media maintain pH around 7.20 until day 7. However, the rate of glucose consumption and lactate production of PCs stored in Viscous PAS (0.3365 mmol/L.day, and 0.7591 mmol/L.day) was roughly half that of the rate exhibited by PCs stored in plasma (0.8447 mmol/L.day, and 1.4258 mmol/L.day). As lactate production and glucose consumption are correlated with in vivo platelet recovery (Goodrich et al., 2006) this augurs well for platelets stored in Viscous PAS. Monitoring the extent of shape change (ESC) and morphology scores for PCs in either of the storage media showed no significant difference on day 7. However, CD62 surface expression and the hypotonic shock response (HSR) were significantly better at day 7 (p<0.05) for platelets stored in the Viscous PAS (37.43 ± 3.31% and 75.76 ± 10.95%, respectively) than stored in plasma (58.37 ± 11.71% and 49.79 ± 15.34%, respectively). We have developed a PAS that is easy to handle in a production environment and because of its osmotic balance and realtive viscosity exhibits equivalent or better storage parameters over a 7 day period than does plasma.