Elimination of cytokine production in stored platelet concentrate aliquots by photochemical treatment with psoralen plus ultraviolet A light

Acute pulmonary injury in hematology patients supported with pathogen-reduced and conventional platelet components

ABSTRACT

Patients treated with antineoplastic therapy often develop thrombocytopenia requiring platelet transfusion, which has potential to exacerbate pulmonary injury. This study tested the hypothesis that amotosalen-UVA pathogen-reduced platelet components (PRPCs) do not potentiate pulmonary dysfunction compared with conventional platelet components (CPCs). A prospective, multicenter, open-label, sequential cohort study evaluated the incidence of treatment-emergent assisted mechanical ventilation initiated for pulmonary dysfunction (TEAMV-PD). The first cohort received CPC. After the CPC cohort, each site enrolled a second cohort transfused with PRPC. Other outcomes included clinically significant pulmonary adverse events (CSPAE) and the incidence of treatment-emergent acute respiratory distress syndrome (TEARDS) diagnosed by blinded expert adjudication. The incidence of TEAMV-PD in all patients (1068 PRPC and 1223 CPC) was less for PRPC (1.7 %) than CPC (3.1%) with a treatment difference of -1.5% (95% confidence interval [CI], -2.7 to -0.2). In patients requiring ≥2 PCs, the incidence of TEAMV-PD was reduced for PRPC recipients compared with CPC recipients (treatment difference, -2.4%; 95% CI, -4.2 to -0.6). CSPAE increased with increasing PC exposure but were not significantly different between the cohorts. For patients receiving ≥2 platelet transfusions, TEARDS occurred in 1.3% PRPC and 2.6% CPC recipients (P = .086). Bayesian analysis demonstrated PRPC may be superior in reducing TEAMV-PD and TEARDS for platelet transfusion recipients compared with CPC recipients, with 99.2% and 88.8% probability, respectively. In this study, PRPC compared with CPC demonstrated high probability of reduced severe pulmonary injury requiring assisted mechanical ventilation in patients with hematology disorders dependent on platelet transfusion. This trial was registered at www.ClinicalTrials.gov as #NCT02549222.

How do I/we forecast tomorrows' transfusion: Blood components

The current implementation of Pathogen Reduction Technologies (PRTs) offers advantages and disadvantages to transfusion medicine. PRT rollout may significantly reduce the incidence of transfusion-transmitted infections and immune reactions, while offering a 'one-size-fits-all' solution to future pathogens in blood products. However, the decrease in transfusion efficacy of PRT-treated blood products suggests that the demand for blood products may increase, further straining the already limited supply of these cells. Conversely, cold-stored platelets and whole-blood transfusions have re-emerged, potentially granting more effective transfusion options to bleeding patients. The renewed focus on donor variability, storage quality, and transfusion outcome presents another avenue through which transfusion quality and supply may be improved.

Transfusion of pathogen-reduced platelet components without leukoreduction

BACKGROUND

Leukoreduction (LR) of platelet concentrate (PC) has evolved as the standard to mitigate risks of alloimmunization, clinical refractoriness, acute transfusion reactions (ATRs), and cytomegalovirus infection, but does not prevent transfusion-associated graft-versus-host disease (TA-GVHD). Amotosalen-ultraviolet A pathogen reduction (A-PR) of PC reduces risk of transfusion-transmitted infection and TA-GVHD. In vitro data indicate that A-PR effectively inactivates WBCs and infectious pathogens.

STUDY DESIGN AND METHODS

A sequential cohort study evaluated A-PR without LR, gamma irradiation, and bacterial screening in hematopoietic stem cell transplant (HSCT) recipients. The first cohort received conventional PC (control) processed without LR, but with gamma irradiation and bacterial screening. The second cohort received A-PR PC (test) processed without: LR, bacterial screening, or gamma irradiation. The primary efficacy outcome was the 1-hour corrected count increment. The primary safety outcome was treatment-emergent ATR. Secondary outcomes included clinical refractoriness, and 100-day status for engraftment, TA-GVHD, HSCT-GVHD, infections, and mortality.

RESULTS

Mean corrected count increment (× 10³ ) of 33 test PC recipients was similar (18.9 ± 8.8 vs. 16.6 ± 8.4; p = 0.296) to that of 31 control PC recipients. Test recipients had a reduced, but nonsignificant, incidence of ATR (test = 9.1%, Control = 19.4%; p = 0.296). The frequencies of clinical refractoriness (0 of 33 vs. 4 of 31 patients) and refractory transfusions (6.6% vs. 19.3%) were lower in the test cohort (p = 0.05 and 0.02), respectively. No patient in either cohort had TA-GVHD. Day 100 engraftment, HSCT-GVHD, mortality, and infectious disease complications were similar between cohorts.

CONCLUSIONS

This study indicated that A-PR PC without LR, gamma irradiation, or bacterial screening is feasible for support of HSCT.

Amotosalen/UVA treatment inactivates T cells more effectively than the recommended gamma dose for prevention of transfusion-associated graft-versus-host disease

INTRODUCTION

Transfusion-associated graft-versus-host disease (TA-GVHD) is a rare complication after transfusion of components containing viable donor T cells. Gamma irradiation with doses that stop T-cell proliferation is the predominant method to prevent TA-GVHD. Treatment with pathogen inactivation methodologies has been found to also be effective against proliferating white blood cells, including T cells. In this study, T-cell inactivation was compared, between amotosalen/ultraviolet A (UVA) treatment and gamma-irradiation (2500 cGy), using a sensitive limiting dilution assay (LDA) with an enhanced dynamic range.

METHODS AND MATERIALS

Matched plasma units (N = 8), contaminated with 1 × 10⁶ peripheral blood mononuclear cells (PBMCs) per mL, were either treated with amotosalen/UVA or gamma irradiation, or retained as untreated control. Posttreatment, cells were cultured under standardized conditions. T-cell proliferation was determined by the incorporation of ³ H-thymidine and correlated with microscopic detection.

RESULTS

Range-finding experiments showed that after gamma irradiation (2500 cGy), significant T-cell proliferation could be observed at a 1 × 10⁷ cell culture density, some proliferation at 1 × 10⁶ , and none at 1 × 10⁵ cells/well. Based on these facts, a quantitative comparison was carried out between amotosalen/UVA at the highest challenge of 1 × 10⁷ PBMCs/well, and gamma irradiation at 1 × 10⁶ and 1 × 10⁵ PBMCs/well. Complete inactivation of the T cells after amotosalen/UVA treatment was observed, equivalent to greater than 6.2 log inactivation. Complete inactivation of the T cells was also observed after gamma irradiation when 1 × 10⁵ PBMCs/well were cultured (>4.2 log inactivation). Proliferation was observed when 1 × 10⁶ PBMCs/well were cultured (≤5.2 log inactivation) after gamma irradiation.

CONCLUSION

Amotosalen/UVA treatment more effectively inactivates T cells than the current standard of gamma irradiation (2500 cGy) for the prevention of TA-GVHD.

Pathogen reduction technologies: The pros and cons for platelet transfusion

The transfusion of platelets is essential for diverse pathological conditions associated with thrombocytopenia or platelet disorders. To maintain optimal platelet quality and functions, platelets are stored as platelet concentrates (PCs) at room temperature under continuous agitation-conditions that are permissive for microbial proliferation. In order to reduce these contaminants, pathogen reduction technologies (PRTs) were developed by the pharmaceutical industry and subsequently implemented by blood banks. PRTs rely on chemically induced cross-linking and inactivation of nucleic acids. These technologies were initially introduced for the treatment of plasma and, more recently, for PCs given the absence of a nucleus in platelets. Several studies verified the effectiveness of PRTs to inactivate a broad array of bacteria, viruses, and parasites. However, the safety of PRT-treated platelets has been questioned in other studies, which focused on the impact of PRTs on platelet quality and functions. In this article, we review the literature regarding PRTs, and present the advantages and disadvantages related to their application in platelet transfusion medicine.

Platelet derived cytokine accumulation in platelet concentrates treated for pathogen reduction

BACKGROUND

Pathogen reduction technologies (PRTs) prevent replication and proliferation of pathogens in platelet (PLT) concentrates (PCs) by modifying nucleic acids. Due to increased cell activation, PRT may also lead to increased cytokine release from α granules and promote adverse transfusion reactions in the recipient.

DESIGN

Fifteen double-dose leukoreduced apheresis PCs were collected on the Trima Accel platform (vs. 5.2.) allowing for the resuspension in PLT additive solution (PAS) immediately after collection. After a 2-h resting period (1st hour without, 2nd hour with agitation), splitting was performed: one unit remained untreated to serve as control (C), while the other was riboflavin-UVB treated using the Mirasol-PRT system according to the manufacturer's instructions (M). During 8 days of storage, PCs were analyzed for contaminating white and red blood cells, bacterial growth, PLT activation, LDH and cytokine release (MIP-1 α, RANTES, PF4, and TGF-β-1). Results obtained were opposed to a former study, where triple-dose PCs underwent Mirasol-PRT prior to resuspension or the INTERCEPT BLOOD SYSTEM (psoralen-UVA) or remained untreated.

RESULTS

Despite similar LDH release, PRT treatment was associated with significantly higher (p<0.05) cell activation but only slightly higher cytokine accumulation during storage. Differences became significant only for PF4 and RANTES at day 8 of storage. On the other hand, in the investigation on triple-dose PCs (yielding higher cytokine levels), TGF beta-1 and RANTES remained significantly (p<0.05) lower after PRT treatment compared to untreated units.

CONCLUSION

Factors, such as collection modality, onset of resuspension and additional amounts of magnesium/potassium in the PAS used may be of equal or even greater impact for cytokine accumulation in stored PCs than PRT treatment.

[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.

Current practice and future directions for optimization of platelet transfusions in patients with severe therapy-induced cytopenia

Platelet transfusions are mainly used for patients with thrombocytopenia due to bone marrow failure, especially cancer patients developing severe chemotherapy-induced thrombocytopenia (e.g. patients with acute leukemia or other hematologic malignancies). A prophylactic transfusion strategy is now generally accepted in developed countries. Some clinical data, however, support the use of a therapeutic transfusion strategy at least for certain subsets of these patients. Several methodological approaches can then be used to evaluate the outcome of platelet transfusions, including peripheral blood platelet increments and bleeding assessments. Several factors will influence the efficiency of platelet transfusions; fever and ongoing hemorrhage are among the most important patient-dependent factors, but the number and quality of the transfused platelets are also important. The quality of transfused platelets can be evaluated by analyzing platelet activation, metabolism or senescence/apoptosis. Only evaluation of metabolism is included in international guidelines, but high-throughput methods for evaluation of activation and senescence/apoptosis are available and should be incorporated into routine clinical practice if future studies demonstrate that they reflect clinically relevant platelet characteristics. Finally, platelet transfusions have additional biological effects that may cause immunomodulation or altered angioregulation; at present it is not known whether these effects will influence the long-time prognosis of cancer patients. Thus, several questions with regard to the optimal use of platelet transfusions in cancer patients still need to be answered.

Pathogen Inactivation of Platelet and Plasma Blood Components for Transfusion Using the INTERCEPT Blood System™

BACKGROUND: The transmission of pathogens via blood transfusion is still a major threat. Expert conferences established the need for a pro-active approach and concluded that the introduction of a pathogen inactivation/reduction technology requires a thorough safety profile, a comprehensive pre-clinical and clinical development and an ongoing hemovigilance program. MATERIAL AND METHODS: The INTERCEPT Blood System utilizes amotosalen and UVA light and enables for the treatment of platelets and plasma in the same device. Preclinical studies of pathogen inactivation and toxicology and a thorough program of clinical studies have been conducted and an active he-movigilance-program established. RESULTS: INTERCEPT shows robust efficacy of inactivation for viruses, bacteria (including spirochetes), protozoa and leukocytes as well as large safety margins. Furthermore, it integrates well into routine blood center operations. The clinical study program demonstrates the successful use for very diverse patient groups. The hemovigilance program shows safety and tolerability in routine use. Approximately 700,000 INTERCEPT-treated products have been transfused worldwide. The system is in clinical use since class III CE-mark registration in 2002. The safety and efficacy has been shown in routine use and during an epidemic. CONCLUSION: The INTERCEPT Blood System for platelets and plasma offers enhanced safety for the patient and protection against transfusion-transmitted infections.

Effect of the psoralen-based photochemical pathogen inactivation on mitochondrial DNA in platelets

Photochemical treatment (PCT) of platelet concentrates, using amotosalen HCl and UVA-light, inactivates pathogens by forming adducts between amotosalen and nucleic acids. The impact of the photochemical treatment on pathogens and leukocytes has been studied extensively. Yet little is known about the effect of PCT on nucleic acids in platelets. Platelets contain viable mitochondria and mitochondrial DNA (mtDNA) and this study aimed at evaluating the amotosalen modifications on platelet mtDNA. We applied two independent but complementary molecular assays to investigate qualitative as well as quantitative aspects of the psoralen-mediated DNA modifications in platelet mtDNA. The amotosalen-DNA modification density was measured using (14)C-labeled amotosalen. Amotosalen (150 microM) yielded 4.0 +/- 1.2 psoralen adducts per 1,000 bp in mtDNA after irradiation with 3 J/cm(2) UVA. Furthermore, we tested if the PCT-induced DNA modifications could be detected by a PCR assay. On the basis of PCR inhibition due to amotosalen-DNA adducts, mtDNA-specific PCR assays were developed and tested for their specificity and sensitivity. Our data revealed that mtDNA in platelets is substantially modified by PCT and that these modifications can be documented by a PCR inhibition system.

Evaluation of White Blood Cell- and Platelet-Derived Cytokine Accumulation in MIRASOL-PRT-Treated Platelets

BACKGROUND: Soluble mediators in platelet concentrates (PCs) released from contaminating white blood cells (WBCs) and platelets (PLTs) themselves are supposed to promote allergic and non-hemolytic febrile transfusion reactions in the recipient. Pathogen reduction technologies (PRTs) prevent replication and proliferation of pathogens as well as of WBCs, and may reduce cytokine accumulation in PCs during storage and prevent adverse events after PLT transfusion. On the other hand, such treatments may also lead to increased cytokine production by stimulation of WBCs or PLTs due to the photochemical or photodynamical process itself. MATERIAL AND METHODS: 12 triple-dose PLT apheresis collections were leukoreduced by the process-controlled leukoreduction system of the Trima Accel machine and split into 3 units undergoing Mirasol-PRT treatment (M) or gamma irradiation (X) or remaining untreated (C). During storage for up to 7 days, PLT activation, WBC-derived Th-1/2, and inflammatory as well as PLT-derived cytokines were measured by cytometric bead array and enzymelinked immunosorbent assay, respectively. RESULTS: Independent of treatment, all PLT products exhibited low levels of WBC-associated cytokines near or below assay detection limits. WBC-associated cytokines were not elevated by Mirasol-PRT treatment. PLT-derived cytokines were detected at higher levels and increased significantly during storage in all units. Most likely due to higher PLT activation, M units showed significantly higher levels of PLT-derived cytokines compared to untreated and gamma-irradiated units on day 5 of storage. CONCLUSION: In all PCs, PLTs themselves were the main source of cytokine release. Mirasol-PRT treatment was associated with a significantly increased PLT activation and accumulation of PLT-derived cytokines during storage, without affecting WBC-derived cytokines relative to controls.

Release of immune modulation factors from platelet concentrates during storage after photochemical pathogen inactivation treatment

BACKGROUND

Blood platelets (PLTs) are critical for hemostasis, and they contain biologically active constituents with the potential to modulate inflammatory responses. This study examined the effects of photochemical pathogen inactivation treatment (PCT) on the release of cytokines and/or chemokines from PLT components.

STUDY DESIGN AND METHODS

Double-dose apheresis PLT components were suspended in plasma-PLT additive solution mixtures and divided into paired therapeutic units. One unit served as an untreated control and the other unit was treated with PCT. PLT concentrations, pH, and levels of cytokines and/or chemokines (CD62p, platelet-derived growth factor-AB, interleukin [IL]-8, soluble CD40 ligand [sCD40L], IL-1beta, and tumor necrosis factor alpha) were measured during 7 days of storage in PLT component supernatants and PLT lysates.

RESULTS

PLT content, pH, and cytokine and/or chemokine content and release from PLT component prepared with PCT were not different (p > 0.05) from paired control components during storage. Levels of sCD40L, however, increased significantly during storage while decreasing in parallel within PLT lysates, although no differences were detected between paired PCT and control PLT component.

CONCLUSION

PCT did not increase the release or secretion of PLT chemokines and/or cytokines over a 7-day period compared to conventional PLT component.

[Platelets cytokines and their effects on platelet transfusion]

Platelets have long been confined to haemostasis only. However, novel functions for platelets have been identified recently. Those non-nucleated cells indeed participate to inflammation and also they produce and release numerous factors with known immunomodulatory functions. Among those factors are cytokines and chemokines and the like, such as soluble CD40-Ligand (CD154), which are key molecules in that they bridge innate and adaptative immunity; sCD40L is active on T cells, B cells, monocytes and macrophages, dendritic cells and endothelial cells lining the blood vessels. This means that when a platelet concentrate is transfused to a recipient, a huge amount of cytokines and chemokines is also infused. In this state of the art review, we will present arguments on the role of platelet secretory products in modulating cellular parameters of immunity, and--very likely--in altering functions of those immune cells upon encounters while infusing platelets in blood recipients. We aimed at summarizing data that have been made available on the issue of cytokines/chemokines released by stored platelets prior to delivery. We will focus on the suspected role of the CD40/CD40L tandem in postplatelet transfusion reactions or incidents. We will present recent data on the role of pathogen inactivators on the docking and/or release of cytokines/chemokines by platelets.

Transfusion-Transmitted Cytomegalovirus: Lessons From a Murine Model

Transfusion-transmitted cytomegalovirus (CMV) infection (TT-CMV) continues to complicate blood transfusion therapy, which can lead to severe morbidity or mortality in immunocompromised or immuno-immature recipients. The biological mechanisms that underlie TT-CMV (eg, viral latency in donor monocytes or stimulatory signals in the transfusion recipient leading to cytomegalovirus reactivation) are difficult to study in humans, but can be addressed in animal models. In this review, we discuss a mouse blood transfusion model, which can be used to investigate these issues as well as to validate methods to prevent TT-CMV in at-risk patients.

Release of potential immunomodulatory factors during platelet storage

BACKGROUND

Blood platelets (PLTs) link the processes of hemostasis and inflammation. Recent studies have demonstrated that PLTs promote immunity and inflammation mainly by means of the CD40/CD40L pathway. Our objective was to describe the accumulation of cytokines in PLT concentrates during storage.

STUDY DESIGN AND METHODS

Pools of PLT concentrates were prepared, separated from plasma, and resuspended in clinical-grade storage medium; samples were taken on Days 0, 1, 2, 3, and 5 for analysis, without replacement (i.e., without soluble protein dilution). Interleukin (IL)-6, IL-8, PLT-derived growth factor (PDGF)-AA, soluble CD40 ligand (sCD40L), RANTES, and transforming growth factor-beta production were measured by specific enzyme-linked immunosorbent assays.

RESULTS

Over time, the levels of RANTES, IL-8, and IL-6 were stable. In contrast, the levels of PDGF-AA and sCD40L increased. Ex vivo production of sCD40L was quantified at levels sufficient to induce B-cell effects based on previous studies of in vitro induced B-cell activation and differentiation by sCD40L. Cytokine and/or chemokine levels were generally higher in PLT concentrate supernatants and/or PLT lysates in comparison to PLT-free plasma, allowing the determination of which cytokine and/or chemokine was absorbed or secreted by transfusion-grade PLTs over time.

CONCLUSION

Our data provide evidence that stored PLTs contain molecules with known immunomodulatory competence and secrete them differentially over time during storage for transfusion purposes.

Cytokine accumulation in photochemically treated and gamma-irradiated platelet concentrates during storage

BACKGROUND

Photochemical treatment (PCT) for pathogen reduction of platelet concentrates (PCs) affects all cells containing DNA and/or RNA. Soluble mediators, which may cause transfusion reactions, are determined by the balance between secretion and/or cell destruction and binding and/or degradation.

STUDY DESIGN AND METHODS

Ten double-dose single-donor leukoreduced PCs were split in two identical units. Two study arms were created: Study Arm A consisting of five PCT PCs with corresponding untreated control PCs and Study Arm B consisting of five PCT PCs with corresponding gamma-irradiated control PCs. PCs that had added PAS-III (Intersol) were treated with amotosalen and ultraviolet A light. Corresponding controls PCs, to which PAS-II (T-sol) were added, received no treatment or were gamma-irradiated before storage. Platelet (PLT)-derived (CCL5/RANTES, CXCL4/PF4, CCL3/MIP-1alpha, transforming growth factor [TGF]-beta, CXCL8/interleukin [IL]-8, IL-1beta) as well as white blood cell (WBC)-associated (IL-6, IL-10, IL-11, IL-12, tumor necrosis factor, interferon-gamma) cytokines were investigated by enzyme-linked immunosorbent assay and cytometric bead array during storage for up to 12 days.

RESULTS

Independent of previous treatment we observed that all concentrates showed low levels of WBC-associated cytokines. PLT-derived cytokines were detected at higher levels and showed significant increase during storage. Statistical analysis showed lower PLT content per unit in PCT PCs, higher levels of activation variables in PCT PCs, and higher levels and accumulation rate of CCL5, CXCL4, TGF-beta, and CXCL8 in PCT PCs.

CONCLUSION

PLTs are the main source of released cytokines during storage of untreated, gamma-irradiated, and PCT PCs. PCT may affect the level of PLT-derived cytokines in PCs. No additional reduction of WBC-associated cytokines were observed after PCT in prestorage leukoreduced PCs.

Clinical safety of platelets photochemically treated with amotosalen HCl and ultraviolet A light for pathogen inactivation: the SPRINT trial

BACKGROUND

A photochemical treatment (PCT) method utilizing a novel psoralen, amotosalen HCl, with ultraviolet A illumination has been developed to inactivate viruses, bacteria, protozoa, and white blood cells in platelet (PLT) concentrates. A randomized, controlled, double-blind, Phase III trial (SPRINT) evaluated hemostatic efficacy and safety of PCT apheresis PLTs compared to untreated conventional (control) apheresis PLTs in 645 thrombocytopenic oncology patients requiring PLT transfusion support. Hemostatic equivalency was demonstrated. The proportion of patients with Grade 2 bleeding was not inferior for PCT PLTs.

STUDY DESIGN AND METHODS

To further assess the safety of PCT PLTs, the adverse event (AE) profile of PCT PLTs transfused in the SPRINT trial is reported. Safety assessments included transfusion reactions, AEs, and deaths in patients treated with PCT or control PLTs in the SPRINT trial.

RESULTS

A total of 4719 study PLT transfusions were given (2678 PCT and 2041 control). Transfusion reactions were significantly fewer following transfusion of PCT than control PLTs (3.0% vs. 4.1%; p = 0.02). Overall AEs (99.7% PCT vs. 98.2% control), Grade 3 or 4 AEs (79% PCT vs. 79% control), thrombotic AEs (3.8% PCT vs. 3.7% control), and deaths (3.5% PCT vs. 5.2% control) were comparable between treatment groups. Minor hemorrhagic AEs (petechiae [39% PCT vs. 29% control; p < 0.01] and fecal occult blood [33% PCT vs. 25% control; p = 0.03]) and skin rashes (56% PCT vs. 42% control; p < 0.001) were significantly more frequent in the PCT group.

CONCLUSION

The overall safety profile of PCT PLTs was comparable to untreated PLTs.

Therapeutic efficacy and safety of photochemically treated apheresis platelets processed with an optimized integrated set

BACKGROUND

This multicenter, randomized, controlled, double-blind Phase III clinical study evaluated the therapeutic efficacy and safety of apheresis platelets (PLTs) photochemically treated (PCT) with amotosalen and ultraviolet A light (INTERCEPT Blood System, Baxter Healthcare Corp.) compared with conventional apheresis PLTs (reference).

STUDY DESIGN AND METHODS

Forty-three patients with transfusion-dependent thrombocytopenia were randomly assigned to receive either PCT or reference PLT transfusions for up to 28 days.

RESULTS

The mean 1- and 24-hour corrected count increments were lower in response to PCT PLTs (not significant). When analyzed by longitudinal regression analysis, the estimated effect of treatment on 1-hour PLT count was a decrease of 7.2 x 10(9) per L (p = 0.05) and on 24-hour PLT count a decrease of 7.4 x 10(9) per L (p = 0.04). Number, frequency, and dose of PLT transfusions; acute transfusion reactions; and adverse events were similar between the two groups. There was no transfusion-associated bacteremia. Four PCT patients experienced clinical refractoriness; however, only one exhibited lymphocytotoxicity assay seroconversion. Antibodies against potential amotosalen-related neoantigens were not detected.

CONCLUSION

PCT PLTs provide effective and safe transfusion support for thrombocytopenic patients.

In vitro evaluation of COM.TEC apheresis platelet concentrates using a preparation set and pathogen inactivation over a storage period of five days

The aim of the present study was to evaluate in vitro data on platelets collected by apheresis, processed on a preparation set followed by photochemical treatment (PCT). Fifteen single-donor platelet concentrates (PCs) were collected by apheresis (COM.TEC blood cell separator, Fresenius, Bad Homburg, Germany). The platelets were transferred to the preparation set and plasma was removed after centrifugation to resuspend the platelets in approximately 37% plasma and 63% platelet additive solution InterSol. PCT was done by exposing the platelets to amotosalen HCl followed by illumination with ultraviolet light. Blood cell counts and in vitro PLT function were measured up to 5 days. An average of 3.44 +/- 0.28 x 10(11) platelets were collected in a product volume of 351 +/- 21 mL. Plasma removal resulted in a mean platelet loss of 7.8%. After PCT, a progressive decrease in platelet function was observed. LDH level rose through storage (171 +/- 81 U/L) to levels approximating LDH levels observed post-collection (180 +/- 103 U/L). There was a gradual decrease of the platelets to respond to hypotonic shock response from 90 +/- 9 % post-plasma reduction to 48 +/- 16% at day 5. All PLT units met the European requirements for leukoreduction and the pH limit of 6.8 up to day 5 post-collection. The new preparation set was capable of producing platelet units meeting the requirements for PCT. Despite differences observed in in vitro platelet function parameters, PLTs at storage day 5 fit the German and European guidelines.

Novel processes for inactivation of leukocytes to prevent transfusion-associated graft-versus-host disease

Transfusion-associated graft-versus-host disease (TA-GVHD) is a serious complication of blood component transfusion therapy. Currently, cellular blood components for patients recognized at risk for TA-GVHD are irradiated prior to transfusion in order to prevent this complication. Considerable progress has been made in elucidating the pathophysiology of this highly morbid complication, but questions as to which patients are at risk and what is the most robust technology to prevent TA-GVHD remain. As new technologies for inactivating or modulating leukocyte function are introduced, the question of how to evaluate these technologies becomes relevant. Over the past two decades, a number of research groups have explored technology to inactivate infectious pathogens and leukocytes contaminating cellular blood components. Few clinicians have an in-depth understanding of the methods or the criteria for selection of how to approach new technologies for leukocyte inactivation with potential to replace current methods. This mini review focuses on the salient aspects of current and evolving technology for prevention of TA-GVHD.

Photochemical treatment of platelet concentrates with amotosalen hydrochloride and ultraviolet A light inactivates free and latent cytomegalovirus in a murine transfusion model

BACKGROUND

A photochemical treatment (PCT) process utilizing amotosalen hydrochloride and long wavelength UVA light has been developed to inactivate pathogens in PLTs. This study investigated the effects of amotosalen/UVA treatment on free and latent murine CMV (MCMV) in PLT preparations using a murine model of transfusion-transmitted CMV (TT-CMV).

STUDY DESIGN AND METHODS

In a model of latent MCMV infection, "donor" mice received 1 x 10(6) plaque-forming units (PFUs) MCMV and were rested 14 days. Subsequently harvested, pooled, and washed WBCs were PCR positive for MCMV. Murine WBC doses of 1 x 10(4), 1 x 10(5), and 1 x 10(6) were added to human apheresis PLTs in 35 percent autologous plasma and 65 percent PLT AS (PAS). The WBC-PLT products were treated with 150 micro mol/L amotosalen and 0.6 J per cm2 UVA and transfused via tail vein injection into recipient mice. Recipients were killed on Day 14. Blood and spleens were collected and assayed for MCMV by PCR. In a parallel model of active infection with free virus, human PLT in 35 percent autologous plasma and 65 percent PAS were dosed with 1 x 10(5) and 1 x 10(6) PFUs of MCMV. All other procedures were as described above.

RESULTS

In the absence of amotosalen/UVA-pretreatment, transfusion of PLT latently or actively infected with MCMV produced TT-CMV in a dose-dependent fashion. In contrast, all transfusion recipients of identical PLT preparations pretreated with amotosalen/UVA were uniformly PCR negative for MCMV (abrogation of TT-CMV; p < 0.05).

CONCLUSIONS

PCT of PLT preparations with the specified doses of amotosalen hydrochloride and UVA light prevents transfusion transmission of free and latent MCMV in a murine model. These results suggest that PCT of human PLTs with amotosalen/UVA should also effectively abrogate TT-CMV in the clinical setting.

Functional characteristics of photochemically treated platelets

BACKGROUND

A photochemical treatment (PCT) process using the psoralen compound amotosalen HCL (S59) and long wavelength UVA light was developed for inactivation of infectious pathogens and WBCs. In this study the effect of PCT on functional characteristics of the platelets was evaluated in vitro.

STUDY DESIGN AND METHODS

Platelet concentrates were treated photochemically using the experimental clinical processing system T-bag S59 Reduction Device (SRD) (n = 4) or the commercially available integral processing system Wafer SRD (n = 4) and compared with control platelet concentrates in plasma/PAS III alone (n = 4). The evaluation included variables with respect to the overall quality of the product (e.g., HSR, pH), the function (aggregation and activation tests), apoptosis (annexin V and caspase 3), and lysis.

RESULTS

No differences were found in the product quality variables, in P-selectin expression, and the apoptosis variables. PCT using the T-bag SRD led to a significant decrease in aggregation capacity with collagen and thrombin and a significant increase in plasma LDH, whereas no differences for the Wafer SRD were found.

CONCLUSION

PCT using the experimental T-bag SRD led to a significant decrease in platelet function. However, the commercially available Wafer SRD had only minor in vitro effects on the quality of the platelets.

[Transfusion-transmitted bacterial infection: residual risk and perspectives of prevention]

Bacterial contamination of blood components represents today the highest infectious risk of blood transfusion, the risk is particularly high when it affects platelet concentrates. The residual risk of transfusion reaction due to bacterial contamination of platelets concentrates remains stable. For all severity 1 case occurs with 25,000 distributed platelets concentrates and 1 death occurs with 200,000 distributed units. In France, efforts have focused on the prevention of contamination during donation--involving measures such as rejecting the first few millilitres of donated blood and improving skin disinfection--and the prevention of bacterial proliferation in platelets concentrates--notably by removing leukocytes and ensuring high-quality storage of donated blood. Improving strategies for reducing the risks of bacterial contamination is one of the priorities of the French National Blood Transfusion Service (l'Etablissement français du sang-EFS). There is currently considerable debate about the relative importance of bacterial screening methods and methods for inactivating pathogens present in PC. Automated culture (Biomérieux) and the ScanSystem (Hemosystem) and BDS (Pall) method are the most advanced detection systems available, to our knowledge. In term of pathogen inactivation system for platelets, Intercept (Baxter) is nearing the commercial market. These new prevention have logistic and/or functional consequences that will require close scrutiny methods. A national study group is currently considering the consequences of each of these methods and should give its opinion at the end of the first half of 2003.

Safety of the blood supply: role of pathogen reduction

Even though the blood supply is very safe, the risk of transfusion transmitted disease is not zero. To improve the safety of the blood supply, pathogen reduction (PR) technology has been developed. The principle of most current PR strategies involves modifying DNA or RNA templates and making them inaccessible to DNA or RNA polymerase. Several platforms of pathogen reduction are available including psoralens, alkylating compounds, binary ethyleneimine-like compounds, riboflavin, methylene blue, and solvent-detergent treatment. PR systems have been designed for RBC, plasma, and platelets. PR technology has been found to be effective for a variety of pathogens including lipid-enveloped and non-enveloped viruses, bacteria and parasites. Pre-clinical studies and Phase III clinical trials to evaluate the efficacy and safety of these PR technologies are currently ongoing.

Advances in pretransfusion infectious disease testing: ensuring the safety of transfusion therapy

The public expects a zero-tolerance policy for the transmission of infectious agents by blood transfusion. Although unrealistic, the efforts to reach this goal have produced an extremely safe albeit costly blood supply [82]. Blood collecting agencies, the FDA, physicians, and scientists have over the past 20 years created a complex system of layers of protection to interdict transfusion-transmitted infections (Fig. 2). As new, exotic, potentially blood transmittable infectious agents evolve [83], new barriers will be erected to [figure: see text] interdict these agents. In the interim, the US blood supply is the safest in the world.

Prevention of transfusion-associated graft-versus-host disease by inactivation of T cells in platelet components

Patients with hematological malignancies and infants with congenital immunodeficiencies who received blood are two of many populations at risk for transfusion-associated graft-versus-host disease (TA-GVHD). Of the methodologies (eg, photoinactivation, peglyation, ultraviolet light, and irradiation) that can be used to prevent TA-GVHD, only irradiation of whole blood and cellular components is currently accepted practice of the US Food and Drug Administration (FDA). Among the newer methods that have been developed to reduce the risks of bacterial and viral contaminants of platelet transfusions, photochemical treatment (PCT) using psoralens and long-wavelength ultraviolet (UVA) irradiation modifies bacterial and viral genomes sufficiently to inhibit replication. Among a broad group of compounds, the synthetic psoralen compound amotosalen hydrochloride (HCl) (S-59) has been shown to be particularly effective in inactivating bacteria and viruses, without adversely affecting in vitro and in vivo platelet function.

Inactivation of WBCs in RBC suspensions by photoactive phenothiazine dyes: comparison of dimethylmethylene blue and MB

BACKGROUND

The transfusion of blood components containing WBCs can cause unwanted complications, which include virus transmission, transfusion-associated GVHD, alloimmunization, febrile reactions, and immunomodulation. Phototreatment with 4 microM of dimethylmethylene blue (DMMB) and 13 J per cm(2) of white light irradiation has previously been shown to be an effective way to inactivate different models of enveloped and nonenveloped viruses in RBC suspensions, with minimum damage to RBCs. The present study compares WBC photoinactivation in buffy coat after DMMB or MB phototreatment under virucidal conditions.

STUDY DESIGN AND METHODS

Buffy coat diluted to 30-percent Hct was treated with the dye and white light. Isolated WBCs were assayed for cell proliferation and viability by an assay using a tetrazolium compound, limiting dilution analysis, DNA fragmentation, and flow cytometry assays.

RESULTS

DMMB and 2.5 J per cm(2) of light phototreatment can inactivate T cells to the limit of detection by limiting dilution analysis (>4.76 log reduction). No WBC proliferation activity was observed after DMMB and 3.8 J per cm(2) of light. DNA degradation after DMMB phototreatment was light dependent. In addition, DMMB phototreatment induced apoptosis in WBCs. In contrast, MB phototreatment under virucidal conditions did not cause significant changes in the viability of WBCs. Neither DNA degradation nor signs of apoptosis were observed after MB phototreatment.

CONCLUSION

DMMB phototreatment inactivates T-lymphocytes, the cells that cause GVHD.

Prevention of Transfusion-Associated Graft-Versus-Host Disease by Photochemical Treatment

Photochemical treatment (PCT) with the psoralen S-59 and long wavelength ultraviolet light (UVA) inactivates high titers of contaminating viruses, bacteria, and leukocytes in human platelet concentrates. The present study evaluated the efficacy of PCT to prevent transfusion-associated graft-versus-host disease (TA-GVHD) in vivo using a well-characterized parent to F1 murine transfusion model. Recipient mice in four treatment groups were transfused with 108 splenic leukocytes. (1) Control group mice received syngeneic splenic leukocyte transfusions; (2) GVHD group mice received untreated allogeneic splenic leukocytes; (3) gamma radiation group mice received gamma irradiated (2,500 cGy) allogeneic splenic leukocytes; and (4) PCT group mice received allogeneic splenic leukocytes treated with 150 μmol/L S-59 and 2.1 J/cm2UVA. Multiple biological and clinical parameters were used to monitor the development of TA-GVHD in recipient mice over a 10-week posttransfusion observation period: peripheral blood cell levels, spleen size, engraftment by donor T cells, thymic cellularity, clinical signs of TA-GVHD (weight loss, activity, posture, fur texture, skin integrity), and histologic lesions of liver, spleen, bone marrow, and skin. Mice in the control group remained healthy and free of detectable disease. Mice in the GVHD group developed clinical and histological lesions of TA-GVHD, including pancytopenia, marked splenomegaly, wasting, engraftment with donor derived T cells, and thymic hypoplasia. In contrast, mice transfused with splenic leukocytes treated with (2,500 cGy) gamma radiation or 150 μmol/L S-59 and 2.1 J/cm2 UVA remained healthy and did not develop detectable TA-GVHD. Using an in vitro T-cell proliferation assay, greater than 105.1 murine T cells were inactivated by PCT. Therefore, in addition to inactivating high levels of pathogenic viruses and bacteria in PC, these data indicate that PCT is an effective alternative to gamma irradiation for prevention of TA-GVHD.

Prevention of Transfusion-Associated Graft-Versus-Host Disease by Photochemical Treatment

Photochemical treatment (PCT) with the psoralen S-59 and long wavelength ultraviolet light (UVA) inactivates high titers of contaminating viruses, bacteria, and leukocytes in human platelet concentrates. The present study evaluated the efficacy of PCT to prevent transfusion-associated graft-versus-host disease (TA-GVHD) in vivo using a well-characterized parent to F1 murine transfusion model. Recipient mice in four treatment groups were transfused with 108 splenic leukocytes. (1) Control group mice received syngeneic splenic leukocyte transfusions; (2) GVHD group mice received untreated allogeneic splenic leukocytes; (3) gamma radiation group mice received gamma irradiated (2,500 cGy) allogeneic splenic leukocytes; and (4) PCT group mice received allogeneic splenic leukocytes treated with 150 μmol/L S-59 and 2.1 J/cm2UVA. Multiple biological and clinical parameters were used to monitor the development of TA-GVHD in recipient mice over a 10-week posttransfusion observation period: peripheral blood cell levels, spleen size, engraftment by donor T cells, thymic cellularity, clinical signs of TA-GVHD (weight loss, activity, posture, fur texture, skin integrity), and histologic lesions of liver, spleen, bone marrow, and skin. Mice in the control group remained healthy and free of detectable disease. Mice in the GVHD group developed clinical and histological lesions of TA-GVHD, including pancytopenia, marked splenomegaly, wasting, engraftment with donor derived T cells, and thymic hypoplasia. In contrast, mice transfused with splenic leukocytes treated with (2,500 cGy) gamma radiation or 150 μmol/L S-59 and 2.1 J/cm2 UVA remained healthy and did not develop detectable TA-GVHD. Using an in vitro T-cell proliferation assay, greater than 105.1 murine T cells were inactivated by PCT. Therefore, in addition to inactivating high levels of pathogenic viruses and bacteria in PC, these data indicate that PCT is an effective alternative to gamma irradiation for prevention of TA-GVHD.