Assessment of the soluble proteins HMGB1, CD40L and CD62P during various platelet preparation processes and the storage of platelet concentrates: The BEST collaborative study

BACKGROUND

Structural and biochemical changes in stored platelets are influenced by collection and processing methods. This international study investigates the effects of platelet (PLT) processing and storage conditions on HMGB1, sCD40L, and sCD62P protein levels in platelet concentrate supernatants (PCs).

STUDY DESIGN/METHODS

PC supernatants (n = 3748) were collected by each international centre using identical centrifugation methods (n = 9) and tested centrally using the ELISA/Luminex platform. Apheresis versus the buffy coat (BC-PC) method, plasma storage versus PAS and RT storage versus cold (4°C) were investigated. We focused on PC preparation collecting samples during early (RT: day 1-3; cold: day 1-5) and late (RT: day 4-7; cold: day 7-10) storage time points.

RESULTS

HMGB1, sCD40L, and sCD62P concentrations were similar during early storage periods, regardless of storage solution (BC-PC plasma and BC-PC PAS-E) or temperature. During storage and without PAS, sCD40L and CD62P in BC-PC supernatants increased significantly (+33% and +41%, respectively) depending on storage temperature (22 vs. 4°C). However, without PAS-E, levels decreased significantly (-31% and -20%, respectively), depending on storage temperature (22 vs. 4°C). Contrastingly, the processing method appeared to have greater impact on HMGB1 release versus storage duration. These data highlight increases in these parameters during storage and differences between preparation methods and storage temperatures.

CONCLUSIONS

The HMGB1 release mechanism/intracellular pathways appear to differ from sCD62P and sCD40L. The extent to which these differences affect patient outcomes, particularly post-transfusion platelet increment and adverse events, warrants further investigation in clinical trials with various therapeutic indications.

Biotinylation of platelets for transfusion purposes a novel method to label platelets in a closed system

BACKGROUND

Labeling of platelets (PLTs) is required to measure the recovery and survival of transfused PLTs in vivo. Currently a radioactive method is used to label PLTs. However, application of those radiolabeling methods is limited by both safety issues and the inability to isolate transfused PLTs from the circulation. Biotin‐labeled PLTs are an attractive nonradioactive option. However, no validated protocol to biotinylate PLTs is currently available for human studies.

STUDY DESIGN AND METHODS

Six PLT concentrates (PCs) were subaliquoted and biotinylated on Days 1 and 7 of storage. To distinguish the effect of the processing steps from the effects of biotin incubation, two control groups were used: 1) “sham” samples were processed without the biotinylation reagent and 2) control samples were assessed without any processing other than the PC isolation. For the biotinylation procedure, 50 mL of PCs was washed twice and incubated with 5 mg/L biotin for 30 minutes in a closed system. As measures of PLT activation, phosphatidylserine exposure and CD62p expression were assessed.

RESULTS

After biotinylation, 98.4% ± 0.9% of PLTs were labeled. PLT counts, pH, and “swirling” were within the range accepted by the Dutch blood bank for standard PLT products. Biotinylated PLTs were more activated compared than controles but not more than sham samples, but were more activated than the controls.

CONCLUSION

We developed a standardized and reproducible protocol according to Good Practice Guidelines standards, for biotin labeling of PLTs for clinical purposes. This method can be applied as nonradioactive alternative assess survival and recovery of transfused PLTs in vivo.

Apheresis causes complement deposition on red blood cells (RBCs) and RBC antigen alterations, possibly inducing enhanced clearance

BACKGROUND

Apheresis is increasingly being applied to collect cells or plasma, even allowing the collection of multiple blood components during one procedure. Although the quality of the cellular and plasma products that are obtained by apheresis have been extensively studied and shown to be of high quality, the impact of apheresis on the red blood cells (RBCs) that are returned to the donor has not been investigated.

STUDY DESIGN AND METHODS

The effect of the plasma- or plateletpheresis procedures by four different devices-MCS+ (Haemonetics), PCS2 (Haemonetics), Trima Accel (Terumo BCT), and Autopheresis-C (Auto-C, Fresenius Kabi)-on the RBCs that are returned to the donor was tested in a blinded, prospective trial in a cohort of 25 donors.

RESULTS

A rheologic analysis of donor RBCs before and after plasma- or plateletpheresis showed no differences in outcome. However, a strong increase in hemolysis was found in samples from the Trima Accel devices after plateletpheresis, compared to all other machines tested. Furthermore, an increase in complement deposition on RBCs was seen after all plasmapheresis procedures (MCS+, PCS2, and Auto-C). Finally, a significant decrease in the expression of the complement-regulating protein CD59 was seen in all postapheresis samples as well as a significant decrease of the adhesion molecule CD147.

CONCLUSION

The increase in complement deposition and the decrease in the expression of CD59 suggests that RBC clearance might be enhanced after return to the donor. Possible side effects due to an increase in hemolysis after Trima Accel plateletpheresis should be further investigated.

In vitro evaluation of the quality of blood products collected and stored in systems completely free of di(2-ethylhexyl)phthalate-plasticized materials

BACKGROUND

The plasticizer di(2-ethylhexyl)phthalate (DEHP) is a common component in blood bags. DEHP is noncovalently bound to polyvinylchloride (PVC) polymer and can leach into the blood product. There are public concerns that exposure to DEHP might induce developmental and reproductive toxicity in humans. The aim of this study was to evaluate an alternative plasticizer, di(isononyl) cyclohexane-1,2-dicarboxylate (Hexamoll DINCH, BASF SE), for its use in blood bags.

STUDY DESIGN AND METHODS

Whole blood (WB) was collected into DEHP-containing and DEHP-free collection systems. After overnight hold, WB was centrifuged and separated in plasma, buffy coat, and red blood cells (RBCs). Buffy coats and plasma were used to make platelet (PLT) concentrates in DEHP-free systems. After addition of additive solution (AS), SAG-M, PAGGS-M, AS-3, or PAGGG-M, RBCs were leukoreduced and analyzed for in vitro characteristics and plasticizer levels during storage.

RESULTS

The use of DINCH-based systems had no effect on WB composition, blood processing, and plasma quality. PLT in vitro quality variables were maintained during storage in DEHP-free systems. During storage in SAG-M, hemolysis was significantly higher in DINCH-PVC while potassium leakage and adenosine triphosphate content were comparable. During storage in alternative ASs, hemolysis was reduced compared to storage in SAG-M.

CONCLUSIONS

The complete absence of DEHP in the collection system had no effect on WB composition, processing, or plasma and PLT quality. During storage in SAG-M, the absence of DEHP resulted in increased hemolysis. With alternative ASs like PAGGS-M, AS-3, or PAGGG-M, the absence of DEHP had no effect on hemolysis. Leakage of DINCH into the blood product was less pronounced than that of DEHP.