P. F. van der Meer

Storage of platelets in additive solutions: a multicentre study of the in vitro effects of potassium and magnesium

Background and Objectives  In a preliminary study, the presence of potassium and magnesium in a modified synthetic medium (PAS‐III) was found to have a significant influence on platelet metabolism (using apheresis‐derived, as well as buffy‐coat‐derived platelets) when compared with standard PAS‐III. The differences included reduced glycolysis, as evidenced by lower consumption of glucose and lower production of lactate, but also better preservation of pH and hypotonic shock response reactivity. The results suggested that storage in modified PAS‐III containing 20% plasma was comparable to storage in standard PAS‐III containing 30% plasma. To confirm the preliminary results and to evaluate the effects of different preparation protocols, an international multicentre study, which included 11 different sites, was conducted.

In vitro comparison of platelet storage in plasma and in four platelet additive solutions, and the effect of pathogen reduction: a proposal for an in vitro rating system.

Background  The introduction of platelet (PLT) additive solutions (PASs) and pathogen reduction (PR) technologies possibly allow extension of PLT shelf life. It was our aim to compare in vitro quality of leucocyte‐reduced PLT concentrates (PCs) stored in various PASs, including PR, with those in plasma during 8 days of storage. The study was performed in four blood centres where each tested four conditions.

UPDATE ON LEUCOCYTE DEPLETION OF BLOOD COMPONENTS BY FILTRATION

It has long been recognized that allogenic leucocytes from donor blood are responsible for serious untoward effects in some transfused patients such as alloimmunization, febrile reactions, platelet refractoriness, transfusion associated acute lung injury, immunosuppression as well as transmission or reactivation of viruses such as CMV, HTLV or EBV. Leucocytes are also known to accelerate the rate of storage lesion. The optimal method to remove leucocytes from blood components has been shown to be filtration. However, many variables exist in the properties of leuco-depletion filters (material, composition, surface charge, mechanisms of leucocyte entrapment), the blood components to be filtered (composition, age), and the filtration method (pre- or post-storage, priming and rinsing, temperature, flow rate). In this paper principles of filtration and subsequent logistic consequences will be discussed. It is recommended to carefully select a filter for a specific blood component and to perform leuco-depletion procedures under controlled conditions according to validated methods meeting Good Manufacturing Practice (GMP) and Good Laboratory Practice (GLP).

Bacterial contamination in platelet concentrates

R. N. I. Pietersz, H. W. Reesink, S. Panzer, S. Oknaian, S. Kuperman, C. Gabriel, A. Rapaille, M. Lambermont, V. Deneys,D. Sondag, S. Ramirez-Arcos, M. Goldman, G. Delage, F. Bernier, M. Germain, T. Vuk, J. Georgsen, P. Morel, C. Naegelen,L. Bardiaux, J.-P. Cazenave, J. Dreier, T. Vollmer, C. Knabbe, E. Seifried, K. Hourfar, C. K. Lin, M. Spreafico, L. Raffaele,A. Berzuini, D. Prati, M. Satake, D. de Korte, P. F. van der Meer, J. L. Kerkhoffs, L. Blanco, J. Kjeldsen-Kragh,A.-M. Svard-Nilsson, C. P. McDonald, I. Symonds, R. Moule, S. Brailsford, R. Yomtovian & M. R. JacobsSeptic reactions after transfusion, particularly of plateletconcentrates, still occur and belong to the most serioustransfusion reactions. From a previous InternationalForum [1] on the subject, it could be concluded that inpart of the countries that participated in the forum, plate-let concentrates (PCs) were tested for bacterial contamina-tion and that culture-based methods, particularly theBacT/Alert system, were used.In recent years, several rapid bacterial detection meth-ods, such as surrogate measurements of the pH or glu-cose, the detection of bacteria with a scan system orPCR tests that detect bacterial RNA, have been devel-oped. These tests can either be performed immediatelyprior to transfusion of the PC or at a variety of testmoments at which culture and release tests are com-bined.Pathogen inactivation (PI) methods also affect bacterialcontamination of PCs. In 2007 [1], in some countries, theIntercept method of PI of PCs was implemented insteadof bacterial screening.It seemed of interest to evaluate the present state ofthe art of this subject. In order to obtain the desiredinformation, the following questions were sent to expertsin the field.Question 1: How long do you store PC and is there adifference between whole-blood-derived PC and apheresisPC? Which method of preparation do you use for whole-blood-derived PC? Are PCs leuco-reduced?Question 2: Do you use a culture method to detect bac-terial contamination of PC? If so,

Interruption of agitation of platelet concentrates: effects on in vitro parameters

Background and Objectives  When platelet concentrates (PCs) are shipped from one centre to another, they may remain unagitated for a considerable period of time. It was therefore our aim to study the effects of interruption of agitation on the in vitro parameters of PCs stored in platelet additive solutions.

Commercially available blood storage containers

Plastic blood bags improve the safety and effectiveness of blood component separation and storage. Progress towards optimal storage systems is driven by medical, scientific, business and environmental concerns and is limited by available materials, consumer acceptance and manufacturing and regulatory concerns. Blood bag manufacturers were invited to submit lists of the bags they manufacture. The lists were combined and sorted by planned use. The lists were analysed by experts to assess the degree to which the products attend to scientific problems. Specific issues addressed included the use of di‐ethylhexyl phthalate (DEHP) as plasticizer for polyvinyl chloride (PVC) blood bags, the size, material and thickness of platelet bags, and the fracture resistance of plasma bags. Alternatives to DEHP for red blood cell (RBC) storage exist, but are mostly in a developmental stage. Plastic bags (DEHP‐free, PVC‐free) for platelet storage with better gas diffusion capabilities are widely available. Alternatives for plasma storage with better fracture resistance at low temperatures exist. Most RBC products are stored in DEHP‐plasticized PVC as no fully satisfactory alternative exists that ensures adequate storage with low haemolysis. A variety of alternative platelet storage systems are available, but their significance – other than improved oxygen transport – is poorly understood. The necessity to remove DEHP from blood bags still needs to be determined.

Leucoreduced platelet concentrates in additive solution: an evaluation of filters and storage containers

Buffy coat (BC) pooling sets are integrated systems, consisting of a pooling bag, a filter and a platelet storage container, for the production of leucoreduced platelet concentrates (LR‐PCs) from pooled BCs. It was our aim to compare various pooling sets that are currently marketed.

Coagulation factor content of plasma produced from whole blood stored for 24 hours at ambient temperature: results from an international multicenter BEST Collaborative study

BACKGROUND: There is increasing international interest in producing components from blood that has been stored at room temperature for 24 hours. The lack of comprehensive data on the quality of plasma produced from blood stored in this way led to this international study.

Preparation of leukodepleted platelet concentrates from pooled buffy coats: prestorage filtration with Autostop BC

Background and Objectives: Our requirements for leukocyte–depleted platelet concentrates (LD–PC) for an adult patient are: platelets >240×109, leukocytes <5×106, volume of 150–400 ml; and at the end of storage a pH between 6.8 and 7.4 and presence of the swirling effect. Our aim was to develop a standardized, semiautomated method for the production of LD–PC, by pooling of buffy coats (BC), and prestorage leukoreduction by filtration. Materials and Methods: Whole blood was collected in Top and Bottom systems, and separated automatically with the Compomat™ G3 equipment into a red cell concentrate, a plasma and a BC. Subsequently, a pool of 5 BC was made, and 200 g plasma from one of the donors was added. Then, after soft spin centrifugation, the platelet rich plasma was leukocyte depleted by filtration using the Autostop™BC filter, and stored in a 1,000 ml polyolefin platelet storage bag. Results: BC (n = 60) had a volume of 51±2 ml (mean ± SD) with a hematocrit of 0.44±0.03 l/l and contained 80±5% of the platelets and 74±12% of the leukocytes of the whole blood. Routinely prepared LD–PC (n = 15,037) contained a median of 341×109 platelets (range 49–599×109), with only 104/15,037 (0.7%) containing fewer than 240×109 platelets; the median volume was 263 ml (range 134–373 ml). In 118/917 (13%) LD–PC leukocytes were observed in the Nageotte hemocytometer, but only twice exceeding 1×106 leukocytes per unit, and none exceeding 5×106 (median <0.6×106; range <0.6–1.41×106). Storage experiments of the LD–PC (n = 12) revealed adequate oxygenation and maintenance of pH and swirling effect up to 9 days. Conclusions: This method warrants with 99% confidence that LD–PC contain more than 240×109 platelets; with 97.5% confidence that 100% of the LD–PC contain <5×106 leukocytes, and with 95% confidence that more than 99% of the LD–PC contain fewer than 1×106 leukocytes; these LD–PC can be stored satisfactorily for up to 9 days.

Comparison of two platelet additive solutions

. The use of an additive solution for substitution of plasma for storage of leukodepleted platelet concentrates can have many advantages. In this study, a comparison was made between two platelet additive solutions: one containing citrate and acetate (PAS‐II), the other also supplemented with additional salts such as magnesium, and with gluconate (Composol‐PS). Donor‐dependent differences were avoided by applying a paired experimental design (n = 10). The platelet concentrates were prepared by pooling five buffy coats and the additive solution, and prestorage filtration was utilized to remove leucocytes to well below 1 × 106. Storage of platelet concentrates up to 9 days after blood collection revealed that platelet concentrates in Composol‐PS maintained an almost constant pH of on average 6·93 from day 2 through day 7, and at 6·90 at day 9. This was in contrast to PAS‐II, which showed a gradually decreasing pH from on average 6·97 at day 1 to 6·86 at day 9. In all units stored in both solutions the swirling effect was present during 9 days of storage. In conclusion, both additive solutions allow storage of platelets, derived from pooled buffy coats, for up to 9 days after collection of the whole blood, with maintenance of good quality in vitro. Composol‐PS has a slightly better buffering capacity, reflected as a more constant pH throughout the storage period.