Aging of platelets stored for transfusion

A goal of platelet storage is to maintain the quality of platelets from the point of donation to the point of transfusion - to suspend the aging process. This effort is judged by clinical and laboratory measures with varying degrees of success. Recent work gives encouragement that platelets can be maintained ex vivo beyond the current 5 -7 day shelf life whilst maintaining their quality, as measured by posttransfusion recovery and survival. However, additional measures are needed to validate the development of technologies that may further reduce the aging of stored platelets, or enhance their hemostatic properties.

Introducing a dexamethasone mouse model for monitoring in vivo viability of stored human platelets

OBJECTIVES

The aim of this study is to establish an available animal model which can evaluate in vivo viability of stored human platelets (HuPLTs).

BACKGROUND

The viability in vivo of HuPLTs was usually evaluated by transfusing HuPLTs into animals before clinical trials. It is necessary to develop a method which may slow down rapid clearance of HuPLTs from circulation of the animal.

METHODS

Carbon clearance tests were performed by treating mice with dexamethasone (DEX) to determine the phagocytic ability of the mice macrophages. HuPLTs in mice whole blood were detected by flow cytometric analysis with mouse anti-human CD41-fluorescein isothiocyanate monoclonal antibody. Recovery and survival of the HuPLTs stored at 22 °C for 1 day were evaluated after transfusing these HuPLTs into DEX-treated mice, and compared with those either stored at 22 °C for 5 days or at 4 °C for 1 day.

RESULTS

Corrected phagocytic indexes of DEX-treated mice decreased significantly compared with those of control mice (P < 0.05). The recovery after 24 h and survival time of fresh HuPLTs in DEX-treated mice were much higher than those in control mice (P < 0.01). After transfused into the DEX-treated mice, HuPLTs stored either at 22 °C for 5 days or at 4 °C for 1 day showed decrease in recovery and survival compared with those stored at 22 °C for 1 day (P < 0.05).

CONCLUSION

Dexamethasone slows down the rate of HuPLTs clearance efficiently in mouse circulation. And the DEX-treated mouse model was able to evaluate the in vivo viability of stored HuPLTs.

Pathogen inactivation of platelets using ultraviolet C light: effect on in vitro function and recovery and survival of platelets

BACKGROUND

We evaluated the effect of treating platelets (PLTs) using ultraviolet (UV)C light without the addition of any photosensitizing chemicals on PLT function in vitro and PLT recovery and survival in an autologous radiolabeled volunteer study.

STUDY DESIGN AND METHODS

For in vitro studies, pooled or single buffy coat-derived PLT concentrates (PCs) were pooled and split to obtain identical PCs that were either treated with UVC or untreated (n = 6 each) and stored for 7 days. PLT recovery and survival were determined in a two-arm parallel autologous study in healthy volunteers performed according to BEST guidelines. UVC-treated or untreated PCs (n = 6 each) were stored for 5 days and were compared to fresh PLTs from the same donor.

RESULTS

There were no significant differences on Day 7 of storage between paired UVC-treated and control PC units for pH, adenosine triphosphate, lactate dehydrogenase, CD62P, CD63, PLT microparticles, and JC-1 binding, but annexin V binding, lactate accumulation, and expression of CD41/61 were significantly higher in treated units (p < 0.05). Compared with control units, the recovery and survival of UVC-treated PC were reduced after 5 days of storage (p < 0.05) and when expressed as a percentage of fresh values, survival was reduced by 20% (p = 0.005) and recovery by 17% (p = 0.088).

CONCLUSION

UVC-treated PLTs stored for 5 days showed marginal changes in PLT metabolism and activation in vitro and were associated with a degree of reduction in recovery and survival similar to other pathogen inactivation systems that are licensed and in use.

Extended storage of platelet-rich plasma-prepared platelet concentrates in plasma or Plasmalyte

BACKGROUND

Using bacterial detection or pathogen reduction, extended platelet (PLT) storage may be licensed if PLT viability is maintained. The Food and Drug Administration (FDA)'s poststorage PLT acceptance guidelines are that autologous stored PLT recoveries and survivals should be 66 and 58% or greater, respectively, of each donor's fresh PLT data.

STUDY DESIGN AND METHODS

Nonleukoreduced PLT concentrates were prepared from whole blood donations. Autologous PLT concentrates from 62 subjects were stored in 100% plasma (n=44) or 20% plasma/80% Plasmalyte (n=18), an acetate-based, non-glucose-containing crystalloid solution previously used for PLT storage. Fresh PLTs were obtained on the day the donor's stored PLTs were to be transfused. The fresh and stored PLTs were alternately radiolabeled with either (51) chromium or (111) indium, and in vitro measurements were performed on the stored PLTs.

RESULTS

The FDA's PLT recovery criteria were met for 7 days of plasma storage, but PLT survivals maintained viability for only 6 days. Plasmalyte-stored PLTs did not meet either acceptance criteria after 6 days of storage. After 7 days of storage, PLT recoveries averaged 43±4 and 30±4% and survivals 4.1±0.4 and 2.0±0.2 days for plasma- and Plasmalyte-stored PLTs, respectively (p=0.03 for recoveries and p<0.001 for survivals). Poststorage PLT recoveries correlated with the commonly used in vitro PLT quality measurements of hypotonic shock response and annexin V binding, while survivals correlated with extent of shape change, morphology score, and pH.

CONCLUSION

There is a progressive decrease in recoveries and survivals of plasma-stored PLTs over time. PLT viability is better maintained in plasma than Plasmalyte.

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 x 10(11)/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/10(12)/24 h in the interval 120-168 h), lactate generation (4.37 vs. 8.11 mmol/10(12)/24 h in the interval 120-168 h), pressure of oxygen (pO(2)) (59.3 vs. 38.1 mmHg at day 1), and HCO(3)(-) (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 (UCL(95)) in recovery and survival of stored PCs below the maximum acceptable difference (MAD); 15.3% UCL(95) < 20.4% MAD and 2.1 days UCL(95) < 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.