Development of HemSol-P^(TM), a Novel Platelet Storage Solution Permitting Storage at 4^o C

The current method of storing platelets as platelet rich plasma (PRP) limits storage life to five days. As many as 10% of platelet units are discarded at a cost of approximately $500 million dollars annually in the U.S. alone. Platelets stored at 22°C remain metabolically active and thus require nutrients supplied in PRP. These nutrition rich platelet preparations promote bacterial growth, demonstrable in approximately one of 3000 platelet units and one of six contaminated units result in clinical sepsis. Also of critical importance, the transfusion of plasma has been associated with transfusion-related acute lung injury (TRALI), which is now the leading cause of transfusion related deaths.

We have developed an innovative preservation technology to address these issues. This process involves mixing cells with a non-toxic proprietary mixture of simple and complex carbohydrates that protect cells from oxidative damage, reduce metabolic activity and allow extended storage. Preliminary studies demonstrate that platelets preserved in this solution (HemSol-P) for up to 14 days at 22°C respond normally to platelet agonist in aggregation assays and had low active GPIIb-IIIa expression and demonstrated low Annexin V binding.

Furthermore, platelets stored in HemSol-P can be maintained at 4^oC for at least 15 days and remain in circulation in a mouse transfusion model. Mouse platelets were isolated from 0.1 ml of blood collected by retro-orbital puncture. Washed platelets were biotinylated and then resuspended in either plasma or HemSol-P to a final concentration of 2x10⁹ platelets/mL and stored at 4°C for up to 15 days. Our results show that platelet survival in the circulation 24 hours after transfusion held steady at 65%, even after 15 days of cold storage in HemSol-P.

HemSol-P has excellent potential for clinical application in transfusion medicine. The potential for cold storage extends shelf life of donated platelets beyond five days. The absence of a plasma component in HemSol-P will likely reduce the incidence of contamination/infection and TRALI, and also reduce overall transfusion costs by increasing the platelet storage time and simplifying procurement and preparation logistics.