Extended storage of single-donor apheresis platelets in CLX blood bags: effect of storage on platelet morphology, viability and in vitro function

Revisitation of the clinical indications for the transfusion of platelet concentrates

Platelet transfusion is indicated when the expected benefits of increasing the number of functional platelets in the patient's circulation outweigh the potential risks generated by exposing the patient to allogeneic, manipulated and stored blood products such as platelet concentrates. Although reassuring evidence has been collected indicating that current risks associated with blood transfusion are lower than those of several voluntary and involuntary human activities, balancing benefits and risks of platelet transfusion may not be easy in a proportion of patients and in a number of conditions. To facilitate this task, guidelines have been developed, with particular attention to cancer patients. As witnessed by the most recent guidelines, over the last few years there has been a progressive, although not absolute, consensus on: (i) the routine use of platelets as a tool to prevent hemorrhage in oncohematology (the so called 'prophylactic approach') as opposed to limiting platelet transfusion to actual bleeding episodes (the so-called 'therapeutic approach') and (ii) lowering the trigger for prophylactic platelet transfusion in stable oncohematology recipients from 20 x 109 to 10 x 109 platelets/L. This has been accompanied by a reduction of platelet use per oncohematology patient of about 20%, an important outcome in view of the progressive increase of platelet demand due to more aggressive therapy in cancer patients. In selected clinical conditions, specific triggers ranging from 30 x 10(9) to 100 x 10(9) platelets/L have been recommended, with higher values when surgical procedures are required for the patient's treatment. Indications and trigger values proposed in the guidelines must be considered within the context of careful clinical evaluation of each patient, with a clear appreciation of the power of discrimination of automated platelet counters at low counts, and of the quality and local availability of platelet products for emergency.

Cost effectiveness of quality assurance in plateletpheresis

BACKGROUND AND OBJECTIVES

A quality assurance system (QAS) is part of modern blood banking facilities. Quality control of single donor platelet (SDP) concentrates includes the determination of the platelet (PLT) yield and the white blood cell (WBC) contamination. Improvements in modern apheresis technology allow the collection of high PLT yields and leukoreduced products. Double dose SDPs can be split and WBC-reduced products may be labelled as leukodepleted thereby reducing costs.

MATERIAL AND METHODS

3309 SDPs obtained with the Amicus, AS 104, AS.TEC 204 and MCS + blood cell separators were retrospectively analysed for their PLT yield. SDPs with > or = 4.0 x 10(11) PLTs were considered as double dose SDPs and split. WBCs were determined microscopically in 170 SDPs. SDPs with a leukocyte content < 1.0 x 10(6) were labelled as leukodepleted and no further WBC filtration was recommended.

RESULTS

PLT yield was statistically higher in SDPs from the Amicus device, 84.8% of these products could be split. Double dose concentrates were collected in 22.7% with the MCS + machine and in 4.8% with the AS 104/AS.TEC 204 blood cell separators. The savings for disposables was $150,041 and for infectious disease testing $75,766. After the subtraction of the costs for PLT determinations in all SDPs $215,880 could be saved. WBC contamination was statistically lowest in in-line filtered SDPs from the MCS + device (median 0.29 x 10(5), range 0.22-9.96 x 10(5)) and all of these products were considered as fulfilling the criterion of leukodepeletion so that we were able to save $17,135 for bedside filters. Median WBC content was 0.75 x 10(5) (range 0.35-22.5 x 10(5)) in SDPs from the Amicus and 0.9 x 10(5) (range 0.27-99.8 x 10(5)) in SDPs from the AS 104/AS.TEC 204 devices, respectively.

CONCLUSION

Blood cell separators of the newest generation allow the collection of leukodepleted double dose SDPs. An intensified QAS in plateletpheresis allows the decision whether a product can be split and/or released as leukodepleted. By this means we were able to save a total of $233,015 per year.

Evaluation of platelets collected by a new portable apheresis device

We studied the efficiency of platelet collection by the Mobile Collection System (MCS) using two types of experimental protocols and evaluated the effect of storage at 22 degrees C on the platelet concentrates (PC). MCS is a new blood cell separator that combines discontinuous flow features with a new computerized operating system and can be used to harvest either full units of apheresis PC (SDP protocol) or half units of PC together with one to two units of plasma (PLP protocol). On the average, 1.98 x 10(11) +/- 0.46 x 10(11) (mean +/- SD) platelets were obtained by the PLP protocol and 3.01 x 10(11) +/- 0.70 x 10(11) and 4.2 x 10(11) +/- 1.12 x 10(11) by the early and later versions of the SDP protocols, respectively. The mean number of WBC per PC ranged from 3.3 to 4.7 x 10(8). During the storage period pH stayed above 7.0. On the average, the production of one molecule of lactate corresponded to the consumption of 0.538 molecules of glucose, indicating that less than 8% of glucose was consumed by the oxidative pathway. There were only small increases in LDH and B thromboglobulin concentrations. Furthermore, the ability of platelets to recover from osmotic shock and to aggregate following exposure to dual agonists declined only slightly during storage, indicating that both viability and function of platelets collected by the MCS were preserved during storage.

Evaluation of elutriated single donor platelets collected and stored in a closed system

Single donor platelets (SDPC) were collected by the elutriation technique in a closed-system integrated with large storage containers. Seven runs of SDPC were stored in a 1.5 liter polyvinyl-chloride trimellitate (PVC-TOTM) storage container, making the ratio of platelet concentrate volume to container volume 1:4.5. An equal volume of pooled multiple donor platelet concentrates (MDPC) was stored in parallel under the same conditions. All haematological data were comparable for both products, except for the degree of leukocyte contamination (5-fold increase in the pool). Under these conditions, the functional, morphological, and metabolic characteristics of elutriated platelets throughout 7-day storage were superior to those of pooled platelets. Although the platelet count was not significantly different in both types of concentrates, the mean pH of pooled MDPC fell to 6.0 on day 5 of storage. Leukocytes were shown to contribute to this pH fall. The extent of cell damage, however, as evidenced by LDH leakage (42.7 LDH units/10(11) platelets/day by differential centrifugation, compared to 5.3 units by elutriation) could not be explained solely on the basis of the leukocyte effect. This indicated that the processing method itself influences the platelet quality. By increasing the surface/volume ratio of SDPC, the initial pH of 7.1 was well maintained throughout storage, platelet metabolic rate was slowed, and the function and ultrastructure improved significantly.

Plateletpheresis with the COBE spectra single needle access option

A group of modifications, including a reservoir bag in the return circuit, has been devised to allow single needle plateletpheresis with the COBE Spectra. We compared the number and quality of platelets collected from 10 subjects in paired donations with single and dual needle protocols. There was no evidence of hemolysis with either protocol. Mean (+/- SD) platelet yields were 3.61 +/- 1.47 x 10(11) with two needles and 3.31 +/- 1.31 x 10(11) with the single needle procedure (P = .13). Mean leukocyte levels (standard manual counting chamber) were 1.0 +/- 1.7 x 10(7) and 1.2 +/- 1.0 x 10(7), respectively (p = .78). pH values during storage were acceptable in both groups of concentrates, and there were no significant differences between the single needle and dual needle concentrates in morphology scores or beta-thromboglobulin levels at 0, 1, 3, or 5 days of storage. Thus the single needle modification produced platelets that were comparable in quantity and quality to those from the standard dual needle plateletpheresis protocol.

Platelet collection with the Autopheresis-C apheresis system

This report describes a new system for collection of platelet concentrate (PC) and cell-free plasma (PPP) from apheresis donors. The system uses two separation devices and requires only a single venipuncture. The Plateletcell device separates primary platelet concentrate (PPC) from anticoagulated whole blood and the Plasmacell-C device separates the PPC into PC and PPP. Results of functional studies performed indicate that the separation process does not alter viability of either the PPC, the PC, or the PPP. Platelet function after 5 days of storage is maintained. An average yield of 3.4 +/- 0.7 x 10(11) platelets in 201 g of PC and 422 g of PPP were harvested in 71 +/- 13 min of donor time from donors with preprocedure hematocrits averaging 42.5 +/- 2.0% and preprocedure platelet counts averaging 265 +/- 61 x 10(3)/microliters.

A novel second-generation polyolefin container for storage of single-donor apheresis platelets

A non-blow-molded LE-2 polyolefin (PO) container was developed to store single-donor apheresis platelet concentrates (PCs) processed by the Haemonetics Plasma Collecting System (PCS) at 22 degrees C for over 1 day. We molded PO containers with heat-sealing of light-weight polymer alloy films with a thickness of 0.25 mm. The film was made of polymer blends consisting of polypropylene, styrene ethylene butylene styrene-block copolymer, and ethylene ethylacrylate copolymer. The PO container with enough strength and flexibility in routine practice has 2 and 1.6 times higher oxygen and carbon dioxide gas transfer properties than standard polyvinyl chloride (PVC) plastic containers. PCs (1-1.9 x 10(11) platelets) processed from 450 ml platelet-rich plasma were stored in 0.6-liter PO containers at 22 degrees C with flatbed agitation for up to 6 days. The pH of PCs was well maintained at the mean values of 7.0 in PO containers after 6 days in the well-oxygenated condition. The energy metabolism of stored platelets was determined. Oxygen consumption rates of platelets stored in PO containers averaged 1.5 nmol/min/10(9) platelets. The rates of glucose consumption and lactate production were 0.4 and 0.8 nmol/min/10(11) platelets, respectively. The rates of adenosine triphosphate (ATP) generation of platelets, 9.7 nmol/min/10(9) platelets, in PO containers did not differ from those in the PVC containers. Aggregation responses to adenosine diphosphate and hypotonic shock response of platelets were better maintained in PO containers. The morphological changes into sphere forms with projections and the appearance of unclassified forms were more frequently observed in PO than in PVC containers.(ABSTRACT TRUNCATED AT 250 WORDS)