Viability of platelets collected by apheresis versus the platelet-rich plasma technique: a direct comparison

Efficacy and Adverse Events of Platelet Transfusion Product-Specific Differences

SUMMARY: TWO PREPARATIONS ARE AVAILABLE FOR PLATELET TRANSFUSION: single-donor apheresis platelet concentrates (APC) and pooled platelet concentrates (PPC) prepared from 4-6 whole blood units. Clear advantages of APC over PPC are a markedly reduced donor exposure of recipients, and easier logistics when attempting a complete supply with ABO-identical and Rh-compatible platelet concentrates. Regulations should aim at complete ABO-identical platelet transfusions because major and minor ABO-incompatible platelet transfusions are probably associated with significantly increased morbidity and mortality. The main advantage of PPC is lower costs. Preparation of PPC is however inevitably accompanied by substantial wastage of plasma and red cells. Only major supraregional blood transfusion centers can guarantee full-coverage supply with ABO-identical and Rh-compatible PPC. Whether APC are more effective than PPC and associated with fewer septic platelet transfusion reactions as shown in some but not all studies, has to be examined in future prospective controlled trials.

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.

In vivo recovery and survival of apheresis and whole blood-derived platelets: a paired comparison in healthy volunteers

BACKGROUND

Methods of platelet preparation may alter the recovery and survival characteristics of platelets following transfusion. As suggested by a recent clinical trial, platelet recovery may be better preserved with apheresis platelet preparations than with platelets prepared from whole blood by the platelet-rich plasma (PRP) method.

STUDY DESIGN AND METHODS

In vivo platelet recovery and survival of autologous leukoreduced (LR) apheresis platelets and autologous filter-LR PRP platelets were compared in 22 healthy volunteers using a paired crossover design. On the same day, each participant gave one apheresis platelet donation and one whole blood donation from which platelets were recovered from the PRP. The sequence of donations was randomly assigned for each participant. Following 5 days of storage and bacterial screening, a sample from each platelet product was labeled with either (51)chromium or (111)indium (randomly assigned) and both samples were simultaneously re-infused into the original donor. Recovery and gamma-function platelet survival were calculated for each platelet product using the multiple hit mathematical model.

RESULTS

Five day stored LR-apheresis platelets had 18.8 percent better recovery, and 32.9 percent longer gamma-survival than filter-LR PRP platelets. Stored apheresis platelets had lower p-selectin expression and higher morphology scores than stored PRP platelets.

CONCLUSIONS

Filter-LR PRP platelet preparation appears to adversely affect platelet recovery and survival characteristics. The reasons for this effect are not clear. These results may not apply to all apheresis and PRP methods of platelet preparation.

Photochemical inactivation of selected viruses and bacteria in platelet concentrates using riboflavin and light

BACKGROUND

A medical device is being developed for the reduction of pathogens in PLT concentrates (PCs). The device uses broadband UV light and the compound riboflavin (vitamin B(2)).

STUDY DESIGN AND METHODS

Pathogens were added to single-donor PLTs. After treatment, the infectivity of each pathogen was measured using established biologic assays. In vitro PLT performance was evaluated after treatment and after 5 days of storage using a panel of 10 in-vitro cell quality assays.

RESULTS

In studies with viral pathogens, the Pathogen Reduction Technology (PRT) system provided average log reduction factors of 4.46 +/- 0.39 for intracellular HIV, 5.93 +/- 0.20 for cells associated HIV, and 5.19 +/- 0.50 for West Nile virus. For the nonenveloped porcine parvovirus, a reduction factor greater than 5.0 log was observed. Staphylococcus epidermidis and Escherichia coli bacteria were also tested with observed reduction factors to the limits of detection of 4.0 log or greater. PLT cell quality was adequately maintained after treatment and during storage. Although P-selectin expression, glucose consumption, and lactate production increased relative to controls, this was not beyond accepted levels. The pH of treated PCs also decreased slightly relative to control PLTs on Days 1 and 5.

CONCLUSION

The data indicate that the device successfully reduced the number of selected pathogens in PCs. Despite the fact that significant differences exist between treated and control in-vitro variables, it is speculated that the clinical effectiveness of both products will not be significantly different, based on comparison to historical data for products in routine clinical use today.

Radioisotopic labels for blood cell survival studies: a review

The different methods of labeling blood cells, in particular erythrocytes and platelets, for survival studies are reviewed. Besides the technical information about these procedures, attention is also paid to the indications of blood cell survival studies, the effective dose equivalent involved and the interpretation of the resulting data. In the final section the possibilities created by dual-labeling procedures are discussed.