Extended Storage of Autologous Apheresis Platelets (Plts) in Plasma and Plasmalyte.

Abstract 2108

Poster Board II-85

Background: The FDA has proposed that, at the end of storage, radiolabeled autologous plt recoveries and survivals should be 67% and 58% respectively, of the same donor's “fresh” plt recovery and survival results. Methods: Using 98 normal subjects, 3 different variables were evaluated to determine their effects on post-storage plt recoveries and survivals; i.e., storage solution (plasma and Plasmalyte), apheresis machine [Haemonetics MCS+ (H), Cobe Spectra (CS), or Cobe Trima (CT)], and storage bag (H, CS, or CT). Autologous plts were collected and either infused “fresh” or stored under the conditions of interest. The fresh and stored plts were alternately radiolabeled with either ⁵¹Cr or ¹¹¹In prior to transfusion. Results: Plasma Storage. Both H and CS collected apheresis plts can be stored for 8 days and meet FDA requirements with no differences in post-storage plt recoveries or survivals between the 2 machines (see table). After 9 days of storage, 2 of 5 units (1 H and 1 CS) had pH's of <6.2, and these plts had recoveries of 36% and 26% and survivals of 1.1 and 0.9 days, respectively.

Plasmalyte Storage. For the H collections, the plts were elutriated using Plasmalyte instead of plasma, and, for the CS and CT collections, the plts were concentrated during collection and re-suspended in Plasmalyte. For all the collections, the final Plasmalyte concentration was 80% with 20% residual plasma. As shown in the table, H collected plts met FDA criteria for 13 days versus 7 days of storage for both CS (FDA criteria not directly tested) and CT collected plts. Even after 7 days of storage, H collected plts were significantly better than CS or CT collected plts with respect to survival (p=0.05), and, after 9 days of storage, H collected plts were significantly better than CS and CT collected plts for both recoveries (p=0.003) and survivals (p<0.001). Recoveries of CS collected plts were better than CT collected plts after 7 days of storage (p=0.01), but the rest of the CS and CT plt recovery and survival data at 7 and 9 days of storage were not different. To determine whether the better results achieved with H plts were because of the machine and/or the storage bag, experiments were performed storing CT or CS collected plts in H bags for 9 or 13 days, respectively. When stored in H bags versus CT bags, 9-day stored CT collected plts had better survivals (p=0.03). Again, CS collected plts stored for 13 days showed a trend for better survivals when stored in H versus CS bags. These data show that both the apheresis machine as well as the storage bag affect the results with the predominant effect being the storage bag. H bag is a ES 3049 PVC compound, and CS and CT bags are PVC with a citrate plasticizer. Low post-storage pH's were found at any storage interval for CS and CT collected plts mainly when stored in their respective bags. pH's <6.2 reduced recoveries by 29% points and survivals by 3.0 days. Therefore, all statistical comparisons between groups were adjusted for the effects of low pH. Conclusion: Apheresis plts can be stored in plasma for 8 days and meet FDA guidelines for plt viability with comparable results between machines and bags. Plt storage in Plasmalyte is effected by both the method of collection as well as the storage bag with the best results achieved with H plts stored in H bags. H plts stored in H bags meet FDA guidelines for 13 days of storage The importance of these results is that extended plt storage can be achieved by using the appropriate combination of storage solution, collection machine, and storage bag.