Susanne Marschner

Pathogen Reduction Technology Treatment of Platelets, Plasma and Whole Blood Using Riboflavin and UV Light

Bacterial contamination and emerging infections combined with increased international travel pose a great risk to the safety of the blood supply. Tests to detect the presence of infection in a donor have a ‘window period’ during which infections cannot be detected but the donor may be infectious. Agents and their transmission routes need to be recognized before specific tests can be developed. Pathogen reduction of blood components represents a means to address these concerns and is a proactive approach for the prevention of transfusion-transmitted diseases. The expectation of a pathogen reduction system is that it achieves high enough levels of pathogen reduction to reduce or prevent the likelihood of disease transmission while preserving adequate cell and protein quality. In addition the system needs to be nontoxic, non-mutagenic and should be simple to use. The Mirasol® Pathogen Reduction Technology (PRT) System for Platelets and Plasma uses riboflavin (vitamin B2) plus UV light to induce damage in nucleic acid-containing agents. The system has been shown to be effective against clinically relevant pathogens and inactivates leukocytes without significantly compromising the efficacy of the product or resulting in product loss. Riboflavin is a naturally occurring vitamin with a well-known and well-characterized safety profile. The same methodology is currently under development for the treatment of whole blood, making pathogen reduction of all blood products using one system achievable. This review gives an overview of the Mirasol PRT System, summarizing the mechanism of action, toxicology profile, pathogen reduction performance and clinical efficacy of the process.

Treatment with riboflavin and ultraviolet light prevents alloimmunization to platelet transfusions and cardiac transplants

Background. Functional leukocytes in blood transfusions can cause alloimmunization. Previous studies have shown that exposure of platelet concentrates to riboflavin and light (Mirasol PRT treatment) causes irreparable modification of nucleic acids. This treatment does not interfere with platelet function but does inhibit a wide range of immunological functions of leukocytes present in platelet concentrates. The current study evaluated the ability of Mirasol treatment to prevent alloimmunization by platelet transfusions in rats. Methods. Lewis rats received eight transfusions of untreated or Mirasol-treated platelets containing leukocytes from DA rats. Animals were subsequently challenged with a heart transplant under cyclosporine treatment. Results. Mirasol treatment caused apoptosis of the leukocytes as measured by annexin V and CD45 staining. Complement split products were deposited on the apoptotic bodies in the platelet pack. The primary and secondary immunoglobulin (Ig) M and IgG responses in rats that received Mirasol-treated platelets were almost completely abolished compared to animals that received untreated platelets. Untreated platelet transfusions elicited strong IgG responses that were associated with rapid rejection of subsequent heart transplants. Rejected hearts contained macrophage infiltrates and C4d deposits. In contrast, no grafts were rejected by recipients transfused with Mirasol-treated platelets. Macrophage infiltrates and C4d deposits were decreased in these grafts. Recipients that were presensitized to untreated platelets were capable of producing a memory response to Mirasol-treated platelets that caused accelerated rejection of subsequent transplants. Conclusions. Transfusions of platelets that were treated with riboflavin and ultraviolet light prevented presensitization to transplants. However, Mirasol-treated platelets were immunogenic in presensitized recipients.

Treatment of whole blood with riboflavin plus ultraviolet light, an alternative to gamma irradiation in the prevention of transfusion-associated graft-versus-host disease?

BACKGROUND: Exposure of blood products to gamma irradiation is currently the standard of care in the prevention of transfusion‐associated graft‐versus‐host disease (TA‐GVHD). Regulatory, technical, and clinical challenges associated with the use of gamma irradiators are driving efforts to develop alternatives. Pathogen reduction methods were initially developed to reduce the risk of microbial transmission by blood components. Through modifications of nucleic acids, these technologies interfere with the replication of both pathogens and white blood cells (WBCs). To date, systems for pathogen and WBC inactivation of products containing red blood cells are less well established than those for platelets and plasma.

Inactivation of human white blood cells in platelet products after pathogen reduction technology treatment in comparison to gamma irradiation

BACKGROUND: During the transfusion of blood products, the transfer of allogeneic donor white blood cells (WBCs) can mediate adverse reactions in recipients. To minimize reactions, blood components are leukoreduced and/or exposed to gamma irradiation. Nucleic acid–targeted pathogen reduction technologies (PRTs) processes are well suited for WBC inactivation. The Mirasol PRT system (CaridianBCT Biotechnologies) uses riboflavin and ultraviolet light to reduce the active pathogen load and inactivate residual WBCs in blood products used for transfusion. The aim of this study was to compare the effect of PRT treatment to gamma irradiation.

Effect of Plasmodium inactivation in whole blood on the incidence of blood transfusion-transmitted malaria in endemic regions: the African Investigation of the Mirasol System (AIMS) randomised controlled trial

BACKGROUND Transfusion-transmitted malaria is a frequent but neglected adverse event in Ghana. We did a randomised controlled clinical trial to assess the efficacy and safety of a whole blood pathogen reduction technology at preventing transfusion transmission of Plasmodium spp parasites. METHODS For this randomised, double-blind, parallel-group clinical trial, eligible adult patients (aged ≥ 18 years) with blood group O+, who required up to two whole blood unit transfusions within 3 days of randomisation and were anticipated to remain in hospital for at least 3 consecutive days after initial transfusion, were enrolled from Komfo Anokye Teaching Hospital in Kumasi, Ghana. The main exclusion criteria were symptoms of clinical malaria, antimalaria treatment within 7 days before randomisation, fever, and haemorrhage expected to require transfusion with up to two units of whole blood during the 3 days following study entry. Eligible patients were randomly assigned 1:1 by computer-generated permuted block randomisation (block size four) list to receive transfusion with either pathogen-reduced whole blood (treated) or whole blood prepared and transfused by standard local practice (untreated). Patients, health-care providers, and data collectors were masked to treatment allocation. Patients in both groups received up to two whole blood unit transfusions that were retrospectively tested for parasitaemia. Pre-transfusion and post-transfusion blood samples (taken on days 0, 1, 3, 7, and 28) were tested for presence and amount of parasite genome, and assessed for haematological and biochemical parameters. The primary endpoint was the incidence of transfusion-transmitted malaria in non-parasitaemic recipients exposed to parasitaemic whole blood, defined as two consecutive parasitaemic post-transfusion samples with parasite allelic matching, assessed at 1-7 days after transfusion. Secondary endpoints included haematological parameters and a safety analysis of adverse events in patients. This study is registered with ClinicalTrials.gov, number NCT02118428, and with the Pan African Clinical Trials Registry, number PACTR201406000777310. FINDINGS Between March 12, 2014, and Nov 7, 2014, 227 patients were enrolled into the study, one of whom was subsequently excluded because she did not meet the inclusion criteria. Of the 226 randomised patients, 113 were allocated to receive treated whole blood and 113 to receive standard untreated whole blood. 223 patients (111 treated and 112 untreated) received study-related transfusions, whereas three patients (two treated and one untreated) did not. 214 patients (107 treated and 107 untreated) completed the protocol as planned and comprised the per-protocol population. Overall, 65 non-parasitaemic patients (28 treated and 37 untreated) were exposed to parasitaemic blood. The incidence of transfusion-transmitted malaria was significantly lower for the pathogen-reduced (treated) patients (1 [4%] of 28 patients) than the untreated group (8 [22%] of 37 patients) in this population (p=0.039). Overall, 92 (41%) of 223 patients reported 145 treatment-related emergent adverse events during the conduct of the study, with a similar incidence of adverse events between groups receiving untreated or treated whole blood. No transfusion-related deaths occurred in the trial. INTERPRETATION Treatment of whole blood with the Mirasol pathogen reduction system for whole blood reduced the incidence of transfusion-transmitted malaria. The primary endpoint of the study was achieved in the population of non-parasitaemic patients receiving parasitaemic whole blood. The safety profile and clinical outcomes were similar across the two treatment groups. FUNDING Terumo BCT Inc.

In vivo viability of stored red blood cells derived from riboflavin plus ultraviolet light-treated whole blood

BACKGROUND: A novel system using ultraviolet (UV) light and riboflavin (Mirasol System, CaridianBCT Biotechnologies) to fragment nucleic acids has been developed to treat whole blood (WB), aiming at the reduction of potential pathogen load and white blood cell inactivation. We evaluated stored red blood cell (RBC) metabolic status and viability, in vitro and in vivo, of riboflavin/UV light–treated WB (IMPROVE study).

Development of a riboflavin and ultraviolet light‐based device to treat whole blood

In the United States, blood components are commonly used for patients in need of massive transfusion after blood loss. In combat situations, when severe traumatic injuries occur far from a hospital, fresh whole blood is a valuable transfusion therapy because components may not be available. The risk of infectious or immunological complications from fresh whole blood transfusions could be mitigated by a system that reduces pathogen loads and inactivates white blood cells (WBCs). Such a system is in development and utilizes riboflavin and ultraviolet light to provide pathogen reduction and WBC inactivation.

The Mirasol® Pathogen Reduction Technology system and quality of platelets stored in platelet additive solution

BACKGROUND The Mirasol Pathogen Reduction Technology system for platelets and plasma uses riboflavin and UV light to introduce irreparable lesions into nucleic acids thereby inhibiting pathogen and white blood cell replication and reducing the load of infectious pathogens. The aim of the present study was to evaluate low plasma buffy coat platelet concentrates obtained from the OrbiSac System and to examine the effects on the development of platelet storage lesion during storage in platelet additive solution. MATERIAL AND METHODS Twenty buffy coat platelet concentrates were generated by pooling five individual units using the OrbiSac System. Riboflavin was added during the final pooling step, and the units were exposed to UV light. The bag was removed after the target energy of 6.24 J/mL had been delivered and 150 mL of platelet additive solution were added prior to storage. Platelet quality was assessed by pH, swirl, CD62P expression, lactate dehydrogenase, lactate production and glucose consumption rates over 7 days of storage. RESULTS Buffy coat platelet concentrates generated on the OrbiSac contained an average 3.5 +/- 0.6 x 10(11) platelets at a concentration of 2976+/- 406 x 10(6)/mL. After addition of 150 mL platelet additive solution the storage concentration was 1043 +/- 148x 10(6)/mL. Values obtained for pH, lactate production and glucose consumption rates were all within the limits of previously established correlations between in vitro cell quality and in vivo performance of Pathogen Reduction Technology-treated platelets in plasma. DISCUSSION In vitro studies show that OrbiSac-derived platelets treated with the Mirasol Pathogen Reduction Technology system preserve adequate function, which would indicate acceptable in vitro viability.

In vitro quality of single-donor platelets treated with riboflavin and ultraviolet light and stored in platelet storage medium for up to 8 days.

BACKGROUND: The Mirasol pathogen reduction technology system is known to increase the activation and metabolic rate of platelets (PLTs). Storage of Mirasol PLTs in PLT storage medium (PSM) has the potential to slow this accelerated PLT storage lesion. We investigated the quality of Mirasol‐treated PLTs stored in either 50% SSP+ or 50% Composol for 8 days.

Inactivation of viruses in platelet and plasma products using a riboflavin-and-UV–based photochemical treatment

Multilayered blood safety programs reduce the risk of transfusion‐transmitted diseases; however, there remains a risk of window period transmission of screened viruses and transmission of unscreened and emerging viruses from asymptomatic donors. To reduce this risk, a riboflavin‐and‐UV‐light–based pathogen reduction process was evaluated against eight viral agents.