Cold-Stored Platelets

by Laurie J. Sutor, MD, MBA

Our practice for decades has been to store platelet components at 20 to 24ºC (“room temperature”). This convention likely arose from the finding that platelets stored at refrigerator temperatures have significantly shorter lifespans in circulation after transfusion.

However, there are clearly disadvantages of room temperature storage of platelet components: 1) Increased risk of bacterial growth, 2) regulatory requirement for either bacterial testing or pathogen reduction of the platelet component, 3) the need for agitation of the product during storage, 4) a short component shelf life (5 to 7 days), and 5) delayed activation of platelet function after transfusion. In addition, more regulation regarding bacterial testing is on the horizon, with a pending FDA guidance document on this topic. Further, there have been recent reports of bacterial contamination of platelet products despite bacterial testing and/or pathogen reduction that led to patient illness or death.

Cold storage could overcome all of these short comings. Currently the FDA allows for cold storage of platelets at 1 to 6ºC without agitation for up to 3 days for trauma patients (21 CFR 640.24 and 640.25). The Mayo Clinic has implemented use of such 3 day platelets for trauma patients in recent years. The military, after significant research and data collection, submitted a variance request to the FDA. This variance was just approved by the FDA in August with the statement “To store apheresis platelets at 1-6 C for up to 14 days without agitation. The cold stored platelet products will be used to treat actively bleeding patient when conventional platelet products are not available, or their use is not practical.” Now that this variance has been approved, other facilities will be able to apply for a similar variance.

Because of the short circulation time after transfusion for cold-stored platelets, they are really only appropriate for actively bleeding patients. Hospitals will have to maintain an inventory of room temperature platelets for cancer and transplant patients.

The big advantage of cold-stored platelets to the community is to improve the flexibility of the platelet inventory. Some smaller or remote hospitals need a platelet to be in stock at all times in case of a trauma or other bleeding patient, but rarely use it. Currently this requires a large expenditure of resources to move platelets around to keep them from out dating. A platelet with a longer shelf life would be very useful for these facilities and help reduce platelet expirations.

Reference:
1. Sepsis attributed to bacterial contamination of platelets associated with a potential common source – multiple states, 2018. SA Jones, JM Jones, V Leung et al. MMWR 2019, 68(23):519-523. (Contamination despite bacterial testing or pathogen reduction)
2. Cold platelets for trauma-associated bleeding: regulatory approval, accreditation approval, and practice implementation – just the “tip of the iceberg”. JR Stubbs, SA Tran, RL Emery et al. Transfusion 2017; 57:2836-2844. (Mayo Clinic implementation)
3. Cold stored platelets in treatment of bleeding. TO Apelseth, AP Cap, PC Spinella et al. ISBT Science Series 2017; 12:488-495. (review)
4. Studies of platelet concentrates stored at 22 C and 4 C. GA Becker, M Tuccelli, T Kunicki et al. Transfusion 1973; 13:61-68. (classic article).