In vitro evaluation of prestorage pooled leukoreduced whole blood-derived platelets stored for up to 7 days

Evaluation of platelet activation in leukocyte-depleted platelet concentrates during storage

Structural and functional changes in platelets during storage can lead to the loss of platelet reactivity and response. Our aim was to evaluate leukocyte-depleted platelet concentrates on storage days 0, 3 and 5, obtained by in-line filtration. In non-filtered platelet concentrates (NF-PC) group, 180 whole blood units were collected with quadruple blood bags and then compared to another group of 180 whole blood units (leukocyte-depleted platelet concentrates [LD-PC]), collected in Imuflex Whole Blood Filter Saving Platelets (WB-SP) bags with an integrated leukoreduction filter, with regard to the platelet quality and characteristics. The efficacy of the two techniques for platelet concentrate preparation was evaluated by white blood cell (WBC) and platelet count on day 0. The partial pressure of oxygen (pO2), pH, platelets positive for P-selectin (CD62P), CD63, cluster of differentiation 42b (CD42b), phosphatidylserine (PS), and mitochondrial membrane potential (MMP) were analyzed during the storage in both groups. A significantly lower WBC count and higher platelet count was observed in LD-PC compared to NF-PC group, indicating the overall efficacy of the first technique. During the 5-day storage, pH and pO2 decreased in both groups. In LD-PC group, higher pH, increased pO2 and decreased platelet surface expression of CD62P, CD63 and PS were observed compared to NF-PC group. In both groups, the percentage of CD42b positive platelets and MMP did not change significantly during the 5-day period. The assessment of different markers of platelet activation may be an effective tool in evaluating the quality of platelets during storage. A better understanding of platelet activation may provide new insights for developing a novel therapeutic approach in the manipulation of platelet aggregation.

Quality control of apheresis platelets: a multicentre study to evaluate factors that can influence pH measurement

BACKGROUND AND OBJECTIVES

Blood operators routinely monitor the pH of apheresis platelets as a marker of the so-called storage lesion, which can result from manufacturing problems. It is also suspected that some donor characteristics can increase the risk of poor platelet storage. To explore this hypothesis, we analysed a large, multinational data set of quality control (QC) pH test results on apheresis platelets.

MATERIALS AND METHODS

For the period between September 2011 and August 2014, seven blood operators in Canada, the USA, the Netherlands, the United Kingdom, France and Australia provided pH QC test results and donor characteristics on a total of 21,671 apheresis platelets.

RESULTS

Some variations in pH distribution between blood operators were in part explained by differences in collection, processing and testing methods. Younger age and female gender were significantly associated with a pH value below the 10th percentile. Among donors who had two or more pH measurements (n = 3672), there was a strong correlation between pH results (r = 0·726; P < 0·0001).

CONCLUSION

The strong intradonor correlation of pH measurements and the association between donor characteristics and pH results suggest that donor factors play a role in the quality of platelets.

Bias, efficiency, and agreement for group-testing regression models

Group testing involves pooling individual items together and testing them simultaneously for a rare binary trait. Whether the goal is to estimate the prevalence of the trait or to identify those individuals that possess it, group testing can provide substantial benefits when compared to testing subjects individually. Recently, group-testing regression models have been proposed as a way to incorporate covariates when estimating trait prevalence. In this paper, we examine these models by comparing fits obtained from individual and group testing samples. Relative bias and efficiency measures are used to assess the accuracy and precision of the resulting estimates using different grouping strategies. We also investigate the agreement of individual and group-testing regression estimates for various grouping strategies and the effects of group size selection. Depending on how groups are formed, our results show that group-testing regression models can perform very well when compared to the analogous models based on individual observations. However, different grouping strategies can provide very different results in finite samples.

The quality of platelet concentrates produced by COBE Spectra and Trima Accel cell separators during storage for 7 days as assessed by in vitro methods

BACKGROUND

The quality of platelet (PLT) concentrates (PCs) can be evaluated with various in vitro methods. A new technique, free oscillation rheometry (FOR), can be used to monitor coagulation properties of PCs and gives information on clotting time and coagulum elasticity. This study compared the quality of apheresis PCs produced by the COBE Spectra and Trima Accel cell separators (both Gambro BCT) during storage for 7 days with in vitro tests including FOR.

STUDY DESIGN AND METHODS

Apheresis PCs were collected with the COBE Spectra (n = 10) and Trima Accel (n = 10) cell separators. Swirling, blood gases, and metabolic variables were analyzed on Day 0. Samples taken on Days 1, 5, and 7 were also analyzed for hypotonic shock response (HSR), P-selectin, and glycoprotein (GP)Ib expression and evaluation of coagulation by FOR.

RESULTS

Swirling, HSR, and percent GPIb-expressing PLTs were well maintained for 7 days, whereas glucose decreased and lactate increased significantly during storage for both Spectra and Trima PCs. Percent P-selectin-expressing cells increased to the same extent in both types of PCs during storage. pH increased between Day 0 and Day 1 but then decreased. The clotting time remained constant throughout the storage period whereas the development of elasticity was reduced on Days 5 and 7 compared to Day 1 (p < 0.05) for both types of PCs.

CONCLUSION

The results indicate that the PLT quality after storage for 7 days is well preserved, although activation of PLTs occurs during storage as assessed by in vitro tests. No difference in PLT quality was observed between Spectra- and Trima-produced PCs.

In vitro evaluation of prestorage pools consisting of mixed A and O platelet concentrates

BACKGROUND

Current FDA regulations allow the prestorage pooling of whole blood-derived platelet concentrates (PCs) of identical ABO type in a recently cleared platelet (PLT) pooling bag (Acrodose, Pall Medical). It is unclear how ABO-mixed PC pools would store if pooled before storage.

STUDY DESIGN AND METHODS

Pools consisting of ABO-identical PLTs and mixed A and O PLTs in varying proportions were evaluated on Days 1, 5, and 7 of storage with measures of the PLT storage lesion, lymphocyte activation, and activation of the complement and coagulation system. Data were analyzed by analysis of variance.

RESULTS

Pools did not differ on Day 7 in pH (p = 0.63), hypotonic shock response (p = 0.25), extent of shape change (p = 0.26), morphology score (p = 0.18), or white cell count (p = 0.79), but surface P-selectin expression was more evident in the ABO-mixed pools (p = 0.02). Small microscopic clumps of PLTs were observed in all pools, but were more prominent in the ABO-mixed pools (p < 0.01). PLT counts, however, did not differ between pools (p = 0.93), indicating that only a small proportion of PLTs were clumped. Surface A-antigen expression was proportional to the number of A PCs in each pool and did not vary between study days. Anti-A(1) titers were either unchanged or decreased by one dilution. Complement and coagulation activation markers did not differ between pools.

CONCLUSION

Pooling A and O PCs is associated with evidence of increased microscopic PLT clumping and activation, but these differences are not exacerbated with 7-day storage. Other major measures of PLT quality do not differ, and there was no evidence of a mixed lymphocyte reaction.

Leukoreduced buffy coat?derived platelet concentrates photochemically treated with amotosalen HCl and ultraviolet A light stored up to 7�days: assessment of hemostatic function under flow conditions

BACKGROUND

Amotosalen plus ultraviolet A light photochemical treatment (PCT) inactivates high titers of bacteria, and other pathogens, in platelet concentrates (PCs) potentially allowing the storage of platelets (PLTs) for up to 7 days. Adhesion and aggregation of PLTs to injured vascular surfaces are critical aspects of PLT hemostatic function.

STUDY DESIGN AND METHODS

Two ABO-identical leukoreduced buffy coat-derived PCs in additive solution were mixed and divided: one-half underwent PCT (PCT-PCs) and the other was kept as a control (C-PCs); both were stored under standard conditions. The total number of paired PCs studied was nine. Samples were taken on Day 1 (before PCT) and after 5 and 7 days of storage. The adhesion and aggregation capacities were evaluated under flow conditions in a ex vivo perfusion model.

RESULTS

Compared to control, PCT resulted in a decrease in PLT count of 6.5 percent (p = 0.004) and 10.2 percent (p = 0.008) after 5 and 7 days' storage, respectively (n = 9). PLT interaction with subendothelium was mainly in form of adhesion. The surface covered by PCT PLTs on Day 1 was 26.0 +/- 4.2 percent (mean +/- SEM). On Day 5, PCT-PCs showed a covered surface of 20.9 +/- 2.2 percent, and the C-PCs, 20.6 +/- 1.6 percent. After 7 days, PCT-PCs produced a nonsignificant higher PLT deposition compared to control (27.1 +/- 2.9% vs. 21.2 +/- 2.8%, p = 0.06).

CONCLUSION

PCT of PCs and storage up to 7 days was associated with a 10.2 percent decrease in PLT count due to processing losses compared to C-PC. PLT adhesive and aggregating capacities under flow conditions of PCT-PCs were similar to C-PCs and remained well preserved for up to 7 days of storage.

Characterization of blood components prepared from whole-blood donations after a 24-hour hold with the platelet-rich plasma method

BACKGROUND

The preparation of platelet (PLT) concentrates (PCs) from PLT-rich plasma (PRP) requires that whole blood (WB) be processed within 8 hours of collection. Increasing WB storage time to 24 hours would be logistically attractive. This study compares the in vitro quality of blood components prepared from WB stored for 8 and 24 hours at room temperature before processing with the PRP method.

STUDY DESIGN AND METHODS

WB units were collected from ABO-matched blood donors. To reduce individual variations, paired donations were drawn in parallel, pooled, and split back in the collection bag. One unit was held for 6 to 8 hours and the other for 22 to 24 hours at 20 to 24 degrees C. Prestorage leukoreduced components were prepared with the PRP as intermediate product and analyzed during storage.

RESULTS

RBC units prepared after an 8- or 24-hour hold were comparable in terms of hemolysis, sodium, pH, and ATP levels. RBC 2,3- diphosphoglycerate (2,3-DPG) was significantly lower in RBCs prepared from 24-hour hold donations immediately after processing but not after 20 days of storage. Residual white blood cells were approximately fivefold higher (p < 0.05) in 24-hour RBC units. For PCs, measurements for glucose, ATP, lactate, pH, extent of shape change, hypotonic shock response, and CD62p activation were similar. No differences were observed in the von Willebrand factor, factor (F)V, FVIII, and fibrinogen content of fresh-frozen plasma.

CONCLUSIONS

The decrease in FVIII and RBC 2,3-DPG can be acceptable as a compromise to improve blood component logistics, but leukoreduction efficiency must be improved before considering the adoption of an overnight storage of WB before PRP processing.

A critical comparison of platelet preparation methods

PURPOSE OF REVIEW

Platelet concentrates may be prepared from whole blood or by plateletpheresis. Currently, the non-evidence-based preponderance of apheresis units in the United States and the 50: 50 ratio in Europe may not optimize the gifts of whole-blood donors or minimize healthcare costs. Post-storage pooled, whole-blood-derived platelets, on the other hand, do not provide the convenience of or an equivalent level of safety as apheresis platelets.

RECENT FINDINGS

Some data suggest that different methods of manufacture of whole-blood-derived platelets (platelet-rich plasma or buffy coat intermediate steps) result in differing degrees of platelet activation, which may impact on the quality of stored concentrates. Recent studies have observed superior radiolabel recovery and post-transfusion increments for platelets derived from apheresis compared with platelet-rich plasma whole-blood-derived platelets. A pre-storage pooling system for whole-blood-derived platelets has just been licensed in the USA, and may eventually combine the benefits of apheresis-derived and whole-blood-derived platelets. The advantages of the European method of manufacture of buffy coat whole-blood-derived platelet concentrate have convinced the Canadian Blood Services to abandon platelet-rich-plasma-derived concentrates.

SUMMARY

We present a literature-based review of the relative merits of apheresis-derived and whole-blood-derived platelets. Additional studies are needed in order to define the optimal proportion of the platelet supply from apheresis collections and the choice of whole-blood-derived production method for US blood providers.

Storage of platelet-rich plasma-derived platelet concentrate pools in plasma and additive solution

BACKGROUND

Prestorage pooling of platelet (PLT)-rich plasma (PRP)-derived PLT concentrates (PCs) and storage in either plasma (PS) or an additive solution (AS) is logistically feasible and would result in a product similar to buffy-coat or apheresis PLTs.

STUDY DESIGN AND METHODS

On Day 0, PS PRP PCs were pooled with a sterile connecting device into a new 1.3-L storage container (ELX, PALL Medical). AS-PCs were prepared by addition of a new low-pH glucose-containing AS to the PLT sediment. AS-PCs were pooled into a 1.3-L ELX bag containing four tablets of NaHCO3. PC pools were sampled on Days 1, 5, and 7.

RESULTS

PS pools containing 5 units had a mean PLT yield similar to the AS pools (39 x 10(10) +/- 3 x 10(10) vs. 37 x 10(10) +/- 6 x 10(10); p = 0.25). All pools had WBC counts of less than 1 x 10(6). pH and HCO3 decreased in PS pools with storage, but either increased or remained constant in the AS pools. On Day 7, no differences were seen in morphology score or extent of shape change. Hypotonic shock response was better preserved in the plasma pools (71 +/- 12% vs. 56 +/- 13%, p < 0.01); however, surface P-selectin was expressed less in the AS pools (6 +/- 4% vs. 18 +/- 10%, p < 0.01).

CONCLUSION

Manufacture and storage of PRP-PCs in pools either in plasma or in a glucose-containing AS in this new container are feasible, and there is good preservation of PLT quality to Day 7.

Platelets: testing, dosing and the storage lesion--recent advances

The demand for platelet transfusions continues to grow. Several complementary approaches that may help meet this demand in the future are reviewed. First, platelet bacterial testing is beginning to allow the extension of platelet storage beyond 5 days. Studies are also underway aimed at better preserving viability and function during ex vivo platelet storage: additive solutions and other approaches are being developed to try to negate the "platelet storage lesion." Finally, new approaches to dosing platelets may help extend the limited supply.