In vitro evaluation of Haemonetics MCS+ apheresis platelet concentrates treated with photochemical pathogen inactivation following plasma volume reduction using the INTERCEPT Preparation Set

Pathogen Reduction Technologies and Their Impact on Metabolic and Functional Properties of Treated Platelet Concentrates: A Systematic Review

Pathogen reduction technologies (PRTs) such as Mirasol and Intercept were developed to eliminate transfusion-transmitted infections. The impact of PRTs on platelet function during the storage period, their effect on platelet storage lesions, and the optimal storage duration following PRTs have not been clearly defined. The aim of this study was to systematically review the existing literature and investigate the impact of PRTs on functional alterations of PRT-treated platelets during the storage period. The authors identified 68 studies suitable to be included in this review. Despite the high heterogeneity in the literature, the results of the published studies indicate that PRTs may increase platelet metabolic activity, accelerate cell apoptosis, and enhance platelet activation, which can subsequently lead to a late exhaustion of activation potential and reduced aggregation response. However, these effects have a minor impact on platelet function during the early storage period and become more prominent beyond the fifth day of the storage period. Large in vivo trials are required to evaluate the effectiveness of PRT-treated platelets during the storage period and investigate whether their storage can be safely extended to more than 5 days, and up to the traditional 7-day storage period.

High platelet content can increase storage lesion rates following Intercept pathogen inactivation primarily in platelet concentrates prepared by apheresis

BACKGROUND

Pathogen inactivation methods for platelet concentrates are increasingly being used in blood banks worldwide. In vitro studies have demonstrated its effects on storage lesion, but little routine quality control data on blood banking outcomes have been reported.

MATERIALS AND METHODS

Swirling of distributed products was monitored before and after implementation of Intercept pathogen inactivation. Metabolic parameters pH, glucose and lactic acid were determined in a random cohort of expired pathogen-inactivated products. Storage lesion indicators in apheresis concentrates with premature low swirling were compared to concentrates with normal swirling.

RESULTS

During validation for implementing Intercept pathogen inactivation, pH and glucose levels decreased faster in apheresis platelet concentrates with high platelet content than with low platelet content or than in pathogen-inactivated pooled buffy coat-derived products. In routine products, glucose exhaustion was more often found in apheresis compared to buffy coat-derived platelet concentrates despite 3-7% more plasma carryover in the former. Annual incidence of premature low swirling increased significantly by 50% following implementation of pathogen inactivation implementation for apheresis but not for pooled buffy coat platelet concentrates. In addition, apheresis concentrates with premature low swirling had a significantly higher median platelet count (5·0 × 10¹¹ ) than unaffected products (3·5 × 10¹¹ ).

CONCLUSION

The risk of increased storage lesion rates following Intercept pathogen inactivation is higher for apheresis than for buffy coat-derived platelet concentrates, especially when platelet contents are higher than 5·0 × 10¹¹ .

The clinical and biological impact of new pathogen inactivation technologies on platelet concentrates

Since 1990, several techniques have been developed to photochemically inactivate pathogens in platelet concentrates, potentially leading to safer transfusion therapy. The three most common methods are amotosalen/UVA (INTERCEPT Blood System), riboflavin/UVA-UVB (MIRASOL PRT), and UVC (Theraflex-UV). We review the biology of pathogen inactivation methods, present their efficacy in reducing pathogens, discuss their impact on the functional aspects of treated platelets, and review clinical studies showing the clinical efficiency of the pathogen inactivation methods and their possible toxicity.

Photo-activated riboflavin therapy of refractory corneal ulcers

PURPOSE

To evaluate the therapeutic effect of photo-activated riboflavin (PAR) for treating refractory corneal ulcers.

METHODS

Seven eyes with infectious keratitis, presented with a gradually deteriorating, vision-threatening, corneal ulcer, despite intense antimicrobial therapy, were treated with PAR. The surgical procedure was deepithelialization of the affected corneas followed by UV-A riboflavin (B2) cross-linking. Local antimicrobial therapy was continued after the procedure.

RESULTS

In all cases, the progression of corneal melting was halted after PAR treatment. Emergency keratoplasty was not necessary in any of the 7 eyes presented. More importantly, all the ulcers were healed without significant vascularization.

CONCLUSION

PAR is a promising option for treating patients with therapy-refractory infectious keratitis to avoid emergency keratoplasty and should be considered as a potential adjuvant therapeutic tool in such eyes.

[Pathogen reduction for platelets: available techniques and recent developments]

The will to reach for blood components a microbiological safety comparable to that of plasma-derived drugs led to the development of numerous pathogen reduction research programs for red blood cells and\or platelets in the 1990s. A consensus conference organized in 2007 allowed to define the main steps and precautions to be taken for the implementation of these processes. In the specific case of platelet concentrates, three processes stay this day in the run, even if they are not at the same development stage. A process using ultraviolet C only is at the stage of preclinical studies. The Mirasol® process, based on the activation of riboflavin by exposure to ultraviolet A and ultraviolet B is CE marked (class IIb), and a clinical study was published in 2010. The Intercept® process, involving the activation of a psoralen molecule by exposure to ultraviolet A, is CE marked (class III) since 2002, and has been licensed in France since 2005, in Germany since 2005 and in Switzerland since 2010. At least 12 clinical studies have been published. In regard to this last pathogen reduction process, the medical and scientific documentation, from in vitro investigations to post-marketing observational studies, is much more developed than the corresponding documentation of some innovative processes at the time of their generalization, such as the SAG-mannitol solution for red cell concentrates in 1979, leukoreduction filters for platelets and red cells concentrates in the 1990s, the solvent detergent therapeutic plasma in 1992 or the methylene blue therapeutic plasma in 2006.

Comparison of platelet activation in platelet concentrates measured by flow cytometry or ADVIA 2120

BACKGROUND AND OBJECTIVES

The ADVIA 2120 Haematology Analyser is capable of measuring parameters that can be used as markers of platelet activation, mean platelet component (MPC), platelet component distribution width (PCDW) and mean platelet mass (MPM). This study investigated the degree of correlation of these measures of platelet granularity with CD62P measurement of platelet activation by flow cytometry in platelet concentrates.

MATERIALS AND METHODS

Pooled platelets in plasma/citrate phosphate dextrose (CPD) anticoagulant or apheresis platelets in plasma/acid citrate dextrose formula A (ACD-A) anticoagulant were evaluated. Pooled platelets were tested during 13 day storage, and apheresis platelets within 24 h of venepuncture. These were assessed for platelet activation using CD62P and the ADVIA, with or without extra EDTA anticoagulant.

RESULTS

In pooled platelets, PCDW correlated strongly with CD62P, both with and without the addition of extra EDTA anticoagulant. There was a good correlation between MPC and CD62P with additional EDTA, but a weaker correlation without extra EDTA. There was no correlation between CD62P and MPM. In apheresis platelets the correlation between PCDW and CD62P was poor, whereas MPC correlated strongly with CD62P if EDTA anticoagulant was added.

CONCLUSION

The usefulness of ADVIA platelet granularity measures to predict the degree of platelet activation depends upon the anticoagulant present in the platelet concentrate, and whether extra EDTA is added to the sample. Although ADVIA MPC and PCDW measurement could not replace CD62P or other gold standard methods of assessing platelet activation, these ADVIA 2120 parameters may provide a quick check of platelet concentrate quality.

[Evolution of techniques for preparation of labile blood products (LBP): pathogen inactivation in LBP]

The techniques for inactivation of pathogens in labile blood products (LBP) would appear to be the new strategy which will permit us to increase transfusion safety in the face of the risks of transmission of pathogenic agents by LBP. Various methods are in the course of development or already validated and used in France. The latter only apply however to plasma or platelet concentrates. The mechanisms of action and the efficacy of inactivation and attenuation of pathogenic agents vary with the different techniques. Each of these constitutes a preparative procedure composed of unit steps which have to be fully mastered in order to ensure the quality and transfusion efficacy of the treated product.

In vitro evaluation of metabolic changes and residual platelet responsiveness in photochemical treated and gamma-irradiated single-donor platelet concentrates during long-term storage

BACKGROUND

Photochemical treatment (PCT) prevents replication of pathogens in platelet concentrates (PCs) by cross-linking nucleic acids and thus affects all cells containing DNA or RNA.

STUDY DESIGN AND METHODS

Fourteen double-dose single-donor PCs were divided into two study arms. The double-dose PCs were split in two identical units, PCT and conventional control PCs. Study Arm A consisted of seven PCT PCs with corresponding untreated controls, whereas Study Arm B consisted of seven PCT PCs with corresponding gamma-irradiated control. Metabolic changes and agonist-induced platelet (PLT) response were evaluated during storage for up to 12 days.

RESULTS

Higher rate of PLT destruction, illustrated by reduced PLT content, increased lactate dehydrogenase levels, and higher CD61+ microparticle formation rate, were observed after PCT. Generally PCT accelerated metabolic changes in PCs and reduced agonist-induced (collagen or thrombin receptor activator peptide [TRAP]) aggregation responses. Flow cytometric analysis of CD62P and CD42b (GPIbalpha) expression showed higher spontaneous PLT activation in PCT PCs from 5 days of storage. Correspondingly, a reduced capacity for up regulation of CD62P expression and down regulation of CD42b was observed in PCT PLTs after stimulation by the agonists ADP or TRAP.

CONCLUSION

Generally reduced in vitro PLT quality was observed after PCT during storage for up to 12 days, with marked reduction from 5 days of storage. Compared to conventional PCs, reduced agonist-induced aggregation and glycoprotein expression were observed after PCT during storage, corresponding to significantly higher level of spontaneous PLT activation in PCT PCs. Clinical studies of efficacy and safety of PCT PCs stored for more than 5 days are recommended.