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. Study Design and Methods In paired experiments (n = 12), buffy coat pools were made to which various storage media were added. Plasma served as reference; two centres used InterSol followed by PR (InterSol+PR) and InterSol without PR; T‐sol, SSP+ and Composol were also studied. Results All PCs fulfilled release criteria (pH_37°C > 6·6; swirl present) until Day 8. Marked differences were seen for other parameters, including CD62P expression: 28 ± 5; 31 ± 7; and 39 ± 9% for T‐sol, Intersol+PR and without PR, respectively, which were higher as found for Composol (12 ± 3%), SSP+ (15 ± 5%) and plasma (15 ± 6%). Three parameters (CD62P, Annexin A5, and lactate concentration) were collapsed into one rating value (6 = good quality, 0 = poor quality); PLTs in plasma had a rating of 2·8 ± 1·0, which was higher as for T‐Sol (1·5 ± 0·5), InterSol+PR (1·3 ± 0·6) and without PR (1·7 ± 0·5). PLTs in potassium‐ and magnesium‐containing PASs showed higher ratings as plasma, 4·3 ± 0·5 for Composol and 3·8 ± 0·8 for SSP+. Conclusion PLT concentrates in plasma, SSP+ and Composol scored better using an arbitrary rating system as PLTs stored in T‐Sol or InterSol; PR further impaired rating parameters. The applicability of these differences in rating for clinical effects needs a clinical study.     

Comparison between in vitro qualities of platelets washed with commercially available additive solutions and those washed with M‐sol

Background and Objectives We previously developed a novel additive solution (M‐sol) with a high ability to preserve the in vitro qualities of platelets (PLTs) in washed PLTs Here, we compared the ability of M‐sol with that of commercially available additive solutions (ASs) to preserve the in vitro qualities (pH, mean PLT volume, %disc, P‐selectin, %hypotonic shock response and aggregation) of PLTs at a low plasma concentration. Materials and Methods The platelet concentrate was divided into two equal aliquots (control group and test group). After centrifugation of both groups and removal of as much supernatant as possible, the pellet of the control group was resuspended in M‐sol and those of the test group were resuspended in other ASs, and subsequently stored in polyolefin bags with agitating at 20–24°C. Results Compared with those stored in M‐sol, the qualities of PLTs stored in PAS‐B (alternative name; PAS‐II or T‐sol), PAS‐ C (alternative name; PAS‐III or Intersol) or Plasma Lyte were degraded as early as 24 h after washing. The qualities of PLTs stored in PAS‐D (alternative name; Composol PS) or PAS‐E (alternative name; PAS‐IIIM or SSP+) were comparable to that of those stored in M‐sol 24 h after washing; however, the qualities had deteriorated 72 h after washing. Conclusions At a low plasma concentration (5% or less), the M‐sol showed a higher ability to preserve PLTs than the five ASs studied here. Although PAS‐D and PAS‐E are available as an AS for short‐term storage of washed PLTs, M‐sol is thought to be preferable for longer storage.     

Platelet storage media

Present platelet storage media often designated platelet additive solutions (PAS) basically contain acetate, citrate and phosphate and recently also potassium and magnesium. However, there seems to be an increasing interest in developing PASs that can be used also after further reduction of residual plasma content below 15–20% plasma. Inclusion of glucose but also calcium and bicarbonate in such solutions have been suggested to improve platelet (PLT) storage, especially when plasma content is reduced to very low levels. Results from a limited number of studies using novel PAS alternatives have been presented during the last years, such as InterSol‐G, PAS‐5, M‐sol, PAS‐G and SAS. Most of them are experimental solutions. The combined results presented in those studies suggest that presence of glucose may be necessary during PLT storage, primarily to maintain ATP at acceptable levels. At plasma inclusion below 15–20%, the content of glucose will generally be too low to support PLT metabolism for more than a few days making glucose addition in PAS necessary. Significant effects associated with presence of calcium was observed in PLTs stored in PAS with 5% inclusion but not with 20–35% plasma inclusion, suggesting that the content of plasma could be of importance. Bicarbonate only seems to be of importance for pH regulation, primarily when plasma inclusion is reduced to about 5%. Reduction in rate of glycolysis was observed in some PAS alternatives containing potassium and magnesium but not in others. Differences in pH or in concentrations of the various compounds included in PAS may be possible explanations. Additionally, novel PAS containing glucose, calcium and bicarbonate does not seem to be associated with improved in vitro results as compared to SSP+ or CompoSol when PLTs are stored with 35% plasma inclusion. The results would then also suggest that excess of glucose in novel PAS environment may not be associated with additional positive effects on PLT metabolism. This review is based on the few publications on novel PAS available, and additional studies would be needed in the future.     

Transfused stored platelets have the same haemostatic function as circulating native platelets

Background and objectives As thrombelastography^® (TEG) measures haemostasis in whole blood, we used this instrument to study whether transfused platelets (PLTs) have the same haemostatic function compared to native circulating PLTs. Further, we studied the effect of storage time on the haemostatic potential of platelet concentrates (PCs). Materials and methods During the decrease in PLT count after chemotherapy, TEG parameters were measured serially until the transfusion trigger was reached in 92 patients. TEG parameters for different ranges of native circulating PLTs could be assessed, which were compared to ranges obtained in the thrombocytopenic period in which the patient received PLT transfusions. Finally, we compared the haemostatic potential of fresh PCs (1–3 days) with PCs with longer storage time (4–5 days). Results No differences could be found in haemostatic potential between native PLTs and transfused stored PLTs (all P‐values ≥ 0·1). The transfusion of fresh PLTs demonstrated better haemostatic effects than longer stored PLTs, measured 1 h after transfusion. Both the time until a fixed level of clot firmness was reached (K‐time) and the rate of clot growth (alpha angle) were superior for fresh PCs. Conclusion TEG is able to monitor the haemostatic effects of PLT transfusion, with comparable haemostatic properties of native circulating and transfused stored‐PLTs. Further, our data suggest that limited storage time is associated with a better haemostatic capacity. However, before TEG can be applied as a qualitative test in PLT transfusion, further research is needed with focus on clinical outcomes like bleeding episodes.     

Washing of platelets can be fully automated using a closed‐system cell processor and BRS‐A platelet additive solution

This study evaluated the in vitro properties of platelets (PLTs) washed with BRS‐A additive solution in the Haemonetics ACP215 automated processing system. Two washing modes, ‘manually/automatically adding ACD‐A to BRS before/during the washing process’, represented the control and test groups, respectively. Outcomes were compared over 7 days of storage (n = 7, for both). PLT recovery following washing processing (26–27 min) was 86·2 ± 1·7% and 86·0 ± 2·2% and plasma protein removal was 98·8 ± 0·3% and 99·0 ± 0·2% in the control and test groups, respectively (not significant). Both groups exhibited comparable in vitro properties.     

Comparison of a novel viscous platelet additive solution and plasma: preparation and in vitro storage parameters of buffy-coat-derived platelet concentrates

Background and Objectives  We developed a viscous platelet additive solution (PAS) based on MacoPharma's SSP+ but containing hydroxyethyl starch to address the poor osmotic balance and low yield associated with conventional PAS for the storage of buffy-coat platelet concentrates (PC).
Materials and Methods  Pools of four buffy-coats were made into leucoreduced PCs ( n  = 5) suspended either in plasma or viscous PAS. After determination of platelet recoveries, the PCs were stored under standard conditions. On days 1, 2, 3, 5, 7 and 9, PCs were tested for mean platelet volume, platelet concentration, soluble protein concentration, CD62 expression, platelet morphology, partial pressure of oxygen and partial pressure of carbon dioxide, glucose and lactate concentration, pH, extent of shape change, and hypotonic shock response (HSR).
Results  Platelets were prepared with greater ease using the viscous PAS and had improved platelet yield. PCs stored in either plasma or viscous PAS displayed similar storage characteristics to day 9. On days 7 and 9 of storage, platelets stored in viscous PAS displayed significantly lower ( P <  0·05) CD62 expression and higher HSR scores than those stored in plasma.
Conclusion  Alteration of the viscosity of PAS improves platelet recovery during processing and may prolong platelet quality at the later stages of storage.     

Quality assessment of platelets stored in a modified platelet additive solution with trehalose at low temperature (10 °C) and in vivo effects on rabbit model of thrombocytopenia

Trehalose is widely used as a cryoprotective reagent to preserve various cells. Platelet additive solution-III (PAS) has been used to maintain platelet function, benefit the virus inactivation, and extend the storage period. PAS with trehalose (PAS-III M?+?T) may effectively protect platelets (PLTs) at a relatively low temperature (10?°C). The apheresis PLTs from six donors were divided into two groups. Group A was stored in PAS-III M?+?T at 10?°C as experimental group and group B in plasma at 22?°C as control group. The samples were collected on different storage dates, and multiple parameters were determined or investigated for in vitro studies. The in vivo recovery and survival of rabbit PLTs stored in the same conditions, and then labeled with ⁵¹Cr were measured and evaluated using a rabbit model of thrombocytopenia. Over 9 days, P-selectin expression increased significantly in a time-dependent manner in both groups (n?=?6). The levels of the hypotonic shock reaction and PLT aggregation rate decreased in both groups and were significantly higher in group A than B after 1 day of storage. The lactate dehydrogenase (LDH) release and glucose (GLU) consumption increased similarly, but the levels were significantly lower in group A than B. The pH decreased significantly after 5 days of storage in group B but did not change in group A. After 5 days, the morphology of the PLTs in group B maintained a more normal shape than that of group A. The recovery and survival of PLTs stored in both groups were not significantly different (p?>?0.05). The bacteria growth was not examined out in both groups for up to 5 (group A) and 9 (group B) days. Storage of PLTs in the modified PAS at low temperature was more effective in protecting PLT functions than that of standard storage method and may have the potential to decrease the risk of PLT activation and bacterial contamination.     

Function and activation state of platelets in vitro depend on apheresis modality

Background and Objectives In multicomponent collection, various blood components are prepared during one apheresis process. The aim of this prospective crossover study was to compare the function, metabolic parameters and activation state of fresh and stored platelets (PLTs) collected by two different cell separators. Materials and Methods Twenty‐four donors underwent apheresis on each of two cell separators (Fenwal Amicus^® and CaridianBCT Trima Accel^®) with an interval of at least 2 months between donations. Per donation, one double dose of PLT concentrate (PC) and one unit of packed red‐blood‐cells were collected. In total, 48 single unit PCs were tested for pH, glucose, bicarbonate, lactate, potassium and LDH concentration during 7 days of storage. PLT function was analysed by aggregometry, rotation thrombelastometry and hypotonic shock response. The PLT surface expression of P‐selectin (CD62P) and LAMP‐3 (CD63) was estimated by flow cytometry. Results During storage, metabolic parameters were well maintained in both groups, but levels of glucose and pH were significantly lower, while lactate and LDH were significantly higher in Amicus^®‐PCs. Amicus^®‐derived PLTs were significantly more activated as evidenced by higher CD62P and CD63 expression. In parallel, the in vitro function of Amicus^®‐PLTs was significantly reduced compared to Trima^®‐PLTs. Conclusion In multicomponent apheresis, standardized PLT collection is effective and well tolerated. The higher activation of Amicus^®‐derived PLTs may be because of the divergent centrifugation modalities during collection. Possible consequences for the clinical outcome of thrombocytopenic patients will be evaluated in further trials.     

Hyperconcentrated platelets stored in additive solution: aspects on productivity and in vitro quality

BACKGROUND AND OBJECTIVES: New platelet (PLT) additive solutions (PASs) allow a plasma carryover of < 30% in PLT concentrates. This implicates the need to collect apheresis PLT concentrates at very high PLT concentrations: so-called dry PLTs (DPs). We used the TRIMA, with software version 4 (TRIMA V4), to collect such DPs and investigated the in vitro quality of these PLTs when stored in the new modified PAS-III (PAS-IIIM). MATERIALS AND METHODS: TRIMA V4 was programmed to collect 6.0 x 10(11) PLTs at a concentration of 5000 x 10(3) PLTs/microl. Two DPs were pooled, split into four equal parts and diluted to obtain secondary pools (SPs) consisting of 70% PAS-III/30% plasma, 70% PAS-IIIM/30% plasma, 80% PAS-IIIM/20% plasma or 100% plasma. In vitro testing was performed on days 0, 1, 5 and 7. Collection efficiency (CE), collection rate (CR) and PLT yield were calculated for each donation. RESULTS: Thirty-two runs with TRIMA V4 were performed, collecting 6.58 +/- 0.74 x 10(11) PLTs at a concentration of 4255 +/- 914 x 10(3)/microl in 99 +/- 19.9 min, resulting in a CE of 65.3 +/- 8.2% and a CR of 6.92 +/- 1.6 x 10(9) PLTs/min. On day 0, 34-37% of the PLTs in the units prepared for storage were already activated. PLTs stored in 70% or 80% PAS-IIIM showed superior in vitro quality compared to PLTs stored in PAS-III. CONCLUSIONS: TRIMA V4 is a suitable device for the collection of DPs. Nevertheless, improvements are desirable to further increase the ability to concentrate PLTs at very high levels. The storage of apheresis-derived PLTs in PAS III-M is a very promising approach, even at a plasma carryover of < 30%.     

High-yield platelet units revealed immediate pH decline and delayed mitochondrial dysfunction during storage in 100% plasma as compared with storage in SSP+

Background and Objectives Initial elevated and prolonged high carbon dioxide levels related to mitochondrial dysfunction are recently being suggested as a contributing factor to rapid pH decline in platelet (PLT) units. The use of different storage environments may influence this phenomenon. This study has two objectives (i) to investigate the relationship of mitochondrial function and apoptotic events with different storage environments capability of pH control and (ii) to examine the cause and relationship between pH decline in PLT units, carbon dioxide levels and mitochondrial function. Materials and Methods Platelet units were prepared for storage in (A) 70% SSP+, 300–400 × 10⁹/unit, (B) 70% SSP+, 550–600 × 10⁹/unit, (C) 100% plasma, 550–600 × 10⁹/unit, and (D) additional 100% plasma, >600 × 10⁹/unit. In vitro variables including mitochondrial function (JC‐1), reactive oxygen species (ROS) and caspase 3 activity were analysed on days 2, 5 and 7. Results Glucose/lactate was higher, pH, ATP, Hypotonic shock response (HSR) and extent of shape change (ESC) decreased (P < 0·001 on day 7), CD62P (P < 0·001 on day 7) increased, the JC‐1‐positive PLTs were lower (P < 0·001 on day 7), and ROS was higher (P < 0·001 days 2–7) in the plasma (C) units as compared with the SSP+ (A) and (B) units. All plasma (D) units showed rapid pH and pCO₂ decline from day 2 but by means of >80% maintenance of mitochondrial function until day 7. Conclusions The use of SSP+ instead of plasma may reduce the risk of triggering pro‐apoptotic events in high‐yield PLT units. A rapid decline in pH in PLT units cannot be explained with initial elevated and prolonged high carbon dioxide levels and mitochondrial dysfunction.     

Storage of Buffy‐coat‐derived platelets in additive solutions: in vitro effects on platelets prepared by the novel TACSI system and stored in plastic containers with different gas permeability

Background The novel TACSI system is designed for automated preparation of platelets (PLTs) from pooled buffy coats (BCs). One TACSI device will handle 6 units at the same time. The aim of our in vitro study is to investigate the effects of using this automated equipment with subsequent storage in two different plastic containers and to compare these results with PLTs prepared by the OrbiSac system. Study design and methods Buffy‐coat‐derived PLTs (n = 8) were prepared by using the TACSI system, including storage in polyvinyl chloride (PVC)‐based plastic containers with di, n‐decyl phthalate (DnDP) (TACSI R) and BTHC (TACSI T)‐based plasticizers. As a reference, the OrbiSac System was used to prepare PLTs (n = 8) with subsequent storage in a PVC plastic container with a citrate‐based plasticizer (BTHC). In total, 16 TACSI and eight reference units, supplied by approximately 30% plasma and 70% SSP+, were analysed for various in vitro variables during the 7‐day storage period. Results No significant difference in PLT counts, LDH, mean platelet volume (MPV) and adenosine triphosphate between the groups was detected. Glucose was lower (P < 0·05) and lactate was higher (P < 0·05) in TACSI R vs. OrbiSac. With exception of day 7 (P < 0·05 TACSI R vs. OrbiSac), HSR reactivity were not different between groups. Extent of shape change was lower and CD62P higher in TACSI T when compared with TACSI R and OrbiSac units (P < 0·05). pH was maintained at >6·8 (day 7) and swirling remained at the highest level (score = 2) for all units throughout storage. Conclusion Platelets prepared by the TACSI system with subsequent storage in two different PVC‐based plastic containers were equivalent to reference PLTs with regard to in vitro characteristics during 7 days of storage.     

In vitro function of buffy coat-derived platelet concentrates stored for 9 days in CompoSol, PASII or 100% plasma in three different storage bags

BACKGROUND AND OBJECTIVES: The aim of the study was to compare the in vitro quality of buffy coat-derived platelet concentrates (PC) during extended storage in plasma or additive solution in three different storage bags. MATERIALS AND METHODS: A pooled and split design was chosen so that identical PCs were produced in either 100% plasma, 70% PASII : 30% plasma or 70% CompoSol : 30% plasma (n = 6 each). This was repeated for three different manufacturers' platelet storage bags (Fresenius, Baxter and Pall). PCs were sampled on days 1, 5, 7 and 9 of storage and tested in vitro using a variety of tests of platelet function. For each bag type, storage in PASII or Composol was compared with plasma (data taken across the entire storage period), and differences occurring with time were analysed for all storage media. RESULTS: The pH of all PCs was > 6.8 at day 9 of storage. In vitro platelet function, as assessed by markers of platelet activation and metabolism, of PCs stored in CompoSol appeared to be similar to that of PCs stored in plasma over 9 days of storage. In contrast, PCs stored in PASII tended to have significantly higher levels of platelet activation (almost a twofold increase in % platelets positive for CD62P by day 5) and lower hypotonic shock response (approximately 40%, by day 7) compared to either PCs stored in 100% plasma or 70% CompoSol. The magnitude of the differences observed between platelet storage media appeared to be dependent on the type of platelet storage bag with the highest degree of platelet activation and lowest hypotonic shock response values being observed in Fresenius bags in combination with PASII. CONCLUSIONS: The maintenance of platelet function in vitro during extended storage of PCs in platelet additive solutions is dependent on the combination of type of additive solution and type of platelet storage bag. For all bag types studied, storage in PASII resulted in poorer platelet function in vitro.     

Feasibility of a closed‐system cell processor (ACP215) for automated preparation of washed platelet concentrates

Background and Objectives This study was aimed at evaluating the feasibility of the ACP215 closed‐system cell processor for preparing washed platelet concentrates. Material and Methods Platelet washing was performed with either the ACP215 system or the manual technique with M‐sol. Plasma protein removal and platelet recovery were estimated, and the washed platelet concentrates were stored for 5 days. Samples were collected after washing and on days 1, 3 and 5 of storage to determine the effects of the washing methods on the in vitro platelet qualities (platelet count, platelet volume, pH, glucose and lactate concentrations, hypotonic shock response, aggregation response and CD62P expression level). Results Platelet recovery was 86·9 ± 2·1% and 85·9 ± 1·9% (P = 0·305), and plasma protein removal was 95·8 ± 0·9% and 96·9 ± 0·7% (P = 0·016) after washing with the ACP215 system and manual technique, respectively. No statistically significant differences in the in vitro platelet qualities were observed between the washing methods. Conclusion The ACP215 system is a feasible alternative to manual, labour‐intensive, techniques for preparing washed platelet concentrates.     

Precise pH measuring of platelet concentrates containing additive solution--the impact of the temperature

Background and Objectives Blood gas analysers measuring pH at 37°C (pH37) are widely used for pH determination of platelet (PLT) concentrates (PCs). For reporting pH at 22°C (pH22), converting of pH37 using the correct conversion factor is mandatory. For PCs stored in PLT additive solution (PAS), such conversion factors are not yet widely available. We studied pH in samples of PCs with different PAS/plasma ratios during warming from 22 to 37°C. Materials and Methods We measured pH in 39 samples containing modified PAS‐III (PAS‐IIIM) with a plasma carryover of 20%, 30% or 40% or no PAS‐IIIM. Differences between pH22 and pH37 (dpH) were compared within and between study groups. Correlation between pH22 and dpH was tested. Additional measurements in 33 samples with three different PLT counts were performed to study the influence of PLT count on dpH. Results pH22 and pH37 within each group and dpH or dpH/dT between study groups differed significantly. The dpH was 0·135 ± 0·040, 0·021 ± 0·009, 0·033 ± 0·011 and 0·048 ± 0·017 for samples containing 100%, 20%, 30% or 40% plasma, respectively. Correlation between dpH and pH22 was strong in 100% (r = 0·696, P < 0·001), weaker in 30% and 40% (r = 0·367, P = 0·022 and r = 0·345, P = 0·032, respectively) and not existing in 20% plasma (r = 0·153, P = 0·354). PLT count did not influence the dpH significantly. Conclusion The dpH is dependent on different PAS‐IIIM/plasma ratios and pH range. For precise reporting of pH22, the respective dpH must be used if converting is necessary. Preferably, the pH should be reported at 37°C or measured directly at 22°C.     

A multicenter randomized study of the efficacy of transfusions with platelets stored in platelet additive solution II versus plasma

Randomized studies testing the clinical efficacy of platelet additive solutions (PASs) for storage of platelets are scarce and often biased by patient selection. We conducted a multicenter, randomized study to investigate clinical efficacy of platelets stored in PAS II versus plasma, also including patients with clinical complications associated with increased platelet consumption. A total of 168 evaluable patients received pooled buffy coat-derived platelet concentrates (PCs) suspended in either plasma (n = 354) or PAS II (n = 411) stored up to 5 days. Both univariate as well as multivariate analysis showed a significant effect of used storage medium in regard to 1- and 24-hour count increments and corrected count increments, in favor of plasma PCs. However, there were no significant differences between the groups regarding bleeding complications and transfusion interval. Adverse transfusion reactions occurred significantly less after transfusions with PAS II PCs (P = .04). Multivariate analysis showed no significant effect of the used storage medium on the incidence of 1- and 24-hour transfusion failure. We showed safety and efficacy of PAS II PCs in intensively treated patients; however, plasma PCs show superior increments.     

In vitro and in vivo effects of potassium and magnesium on storage up to 7 days of apheresis platelet concentrates in platelet additive solution

BACKGROUND AND OBJECTIVE: Prolonged storage of platelets up to 7 days provides improved availability, logistical management and decreased wastage. Beside methods of bacterial detection, addition of magnesium and potassium to the platelet storage solution (SSP+) may further improve the quality of platelets with extended storage. MATERIALS AND METHODS: Apheresis platelets from 10 donors were divided and stored in two different platelet additive solutions (PAS) (Intersol and SSP+) for a paired comparison. A variety of in vitro platelet function and metabolic assays were performed both on day 1 and after 7 days of storage. For in vivo study, platelets were labelled with either (111)Indium or (51)Chromium after 7 days of storage and were injected into the corresponding donor. Serial blood samples were drawn for recovery and survival measurements. RESULTS: In vitro parameters for SSP+ showed significantly reduced glycolysis (lower glucose consumption and decreased production of lactate), a higher hypotonic shock response (HSR) and the extent of shape change reactivity and a lower degree of platelet activation by means of RANTES (regulated on activation, normal, T cell-expressed, and secreted), CD62p and CD63 expression. Platelet recovery on day 7 was higher for Intersol as compared to SSP+, 65 +/- 11 vs. 53 +/- 13% (P = 0.023), and survival showed no difference 4.2 +/- 1.9 vs. 3.6 +/- 1.4 days. CONCLUSION: In vitro characteristics of platelets stored in PAS with addition of potassium and magnesium indicated higher quality, but this could not be verified by the in vivo parameters by means of recovery and survival.     

In vitro effects on platelets irradiated with short-wave ultraviolet light without any additional photoactive reagent using the THERAFLEX UV-Platelets method

Background A novel short‐wave ultraviolet light (UVC) pathogen reduction technology (THERAFLEX UV‐Platelets; MacoPharma, Mouvaux, France) without the need of any additional photoactive reagent has recently been evaluated for various bacteria and virus infectivity assays. The use of UVC alone has on the one hand been shown to reduce pathogens but may, on the other hand, have some impact on the platelet (PLT) quality. The purpose of this study was to determine the potential effects on PLT quality of pathogen inactivation treatment using the novel UVC method for PLT concentrates. Study Design and Methods Buffy‐coat‐derived PLTs suspended in SSP+ were irradiated with UVC light in plastic bags (MacoPharma) made of ethyl vinyl acetate, considered to be highly permeable to UVC light. The UVC‐treated (test, n = 8) as well as the untreated (reference, n = 8) PLT units were stored in PLT storage bags composed of n‐butyryl, tri n‐hexyl citrate–plasticized polyvinyl chloride (MacoPharma) on a flat bed agitator for in vitro testing during 7 days of storage. Results No significant difference in PLT counts and lactate dehydrogenase between the groups was detected. During storage, glucose decreased more and lactate increased more in the test units. Statistically significant differences were found for glucose (P < 0·01) and lactate (P < 0·05) on day 7. ATP levels were higher (P < 0·01 from day 5) in the reference units. With exception of day 7 (P < 0·01 reference vs. test), hypotonic shock response reactivity was not different between groups. Extent of shape change was lower (P < 0·01), and CD62P (P < 0·05 day 5) was higher in the test units. CD42b and CD41/61 showed similar trends throughout storage, without any significant difference between the units. pH was maintained at >6·8 (day 7) and swirling remained at the highest level (score = 2) for all units throughout storage. Conclusion Our results suggest that irradiation with UVC light has a slight impact on PLT in vitro quality and appears to be insignificant with regard to current in vitro standards.     

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. MATERIALS AND METHODS: In this multicentre study, PCs were prepared either by apheresis or from pooled buffy coats, paired to minimize donor-dependent differences, and aliquoted into 3 units with a 'low concentration' (approximately 1 x 10(9) platelets/ml; groups A, B and C) and 3 units with a 'high concentration' (approximately 2 x 10(9) platelets/ml; groups D, E and F). The final composition of the storage medium was 30% plasma and 70% additive solution in all PCs. Either PASIIIM or Composol was used as the additive solution. Agitation was interrupted for 2 days (between days 3 and 5, groups A and D), or for 4 days (between days 1 and 5, groups B and E), and continuous agitation served as the reference (groups C and F). A number of in vitro parameters were used for testing on days 1, 5 and 7. RESULTS: On day 7, reference units C and F in PASIIIM had significantly higher pH values than the study units in PASIIIM, but all retained a pH of > 6.5 at 37 degrees C. Hypotonic shock response (HSR) results were significantly lower in the high concentration/4-day interruption group (E) than in the other groups. The low-concentration groups in PASIIIM, with agitation interrupted for either 2 days (group A) or 4 days (group B), did not have HSR values significantly different from the respective references. Study groups A, B, D and E in Composol, a solution lacking phosphate, had a pH of approximately 6.5 on day 7, which was significantly lower than that of the references and of the corresponding units in PASIIIM. The pH values were > 7.0 in reference groups C and F in Composol, not significantly different from those in PASIIIM. HSR values were also significantly lower in the Composol study groups. On the other hand, the reference Composol groups showed results similar to units in PASIIIM. CONCLUSIONS: PCs in PASIIIM additive solution with a platelet concentration of approximately 1 x 10(9)/ml can sustain 4 days without agitation. Phosphate may be of importance in maintaining good in vitro characteristics during interruption of agitation.     

Survival and recovery of apheresis platelets stored in a polyolefin container with high oxygen permeability

Background and Objectives Oxygen permeability is important in platelet storage media. We compared a new polyolefin container with enhanced oxygen permeability (PO‐80; Kawasumi, Tokyo, Japan) to a widely used alternative (PL2410; Baxter Healthcare, Deerfield, IL, USA). Materials and Methods In vitro characteristics of paired platelet concentrates (PCs; mean 4·2 × 10¹¹/250 ml plasma/bag) stored in PO‐80 or PL2410 were assessed through 9 days of storage. In vivo recovery and survival of 7‐day‐old autologous PCs were assessed according to the Murphy method. Results Laboratory assessment of platelet quality favoured PO‐80 during 9 days of storage with statistically significant differences in glucose consumption (2·75 vs. 4·93 mmol/10¹²/24 h in the interval 120–168 h), lactate generation (4·37 vs. 8·11 mmol/10¹²/24 h in the interval 120–168 h), pressure of oxygen (pO₂) (59·3 vs. 38·1 mmHg at day 1), and (14·7 vs. 13·4 mmol/l at day 1). Statistically significant differences were not seen in aggregation, hypotonic shock response or pH. In vivo assessment of autologous platelets stored 7 days in the PO‐80 container revealed that recovery was 82·1% and survival was 81·0% of fresh control. Seven‐day stored PCs in PO‐80 were shown in vivo to be non‐inferior to fresh platelets, with upper confidence limits (UCL₉₅) in recovery and survival of stored PCs below the maximum acceptable difference (MAD); 15·3% UCL₉₅ < 20·4% MAD and 2·1 days UCL₉₅ < 2·1 days MAD. Conclusions The in vitro characteristics of PCs stored in a highly oxygen‐permeable container were stable at least 7 days. The in vivo study supports the suitability of PO‐80 for 7‐day platelet storage.     

Methods for testing platelet function for transfusion medicine

Background Currently only indirect measures are required for monitoring the function of platelets in platelet concentrates (PC). Methods This is an overview on currently available commercialized methods that have been used to determine platelet function in donors, concentrates and after transfusion. We show examples for the application of the no/low shear methods light‐transmission aggregometry, flow cytometry, multiple electrode aggregometry, thrombelastography and dynamic light scattering, and those applying high shear, the platelet function analyzer‐100, and the cone and plate analyzer. Advantages and disadvantages of the various methods to screen donors, evaluate the haemostatic properties maintained in the PC and after transfusion are discussed, based on considerations of platelet physiology, and the feasibility of the various procedures. This survey focuses on reports from the last 10 years, as the technology for the production of PCs has advanced significantly during the last few years. Conclusion Specific aspects of platelet function can be assessed by the no/low shear methods, while the high shear methods provide more general analysis of platelet haemostatic competence. Yet, there is no strong evidence that the in vitro data correspond with the clinical outcome.