Decolonization and Pathogen Reduction Approaches to Prevent Antimicrobial Resistance and Healthcare-Associated Infections.

Antimicrobial resistance in healthcare-associated bacterial pathogens and the infections they cause are major public health threats affecting nearly all healthcare facilities. Antimicrobial-resistant bacterial infections can occur when colonizing pathogenic bacteria that normally make up a small fraction of the human microbiota increase in number in response to clinical perturbations. Such infections are especially likely when pathogens are resistant to the collateral effects of antimicrobial agents that disrupt the human microbiome, resulting in loss of colonization resistance, a key host defense. Pathogen reduction is an emerging strategy to prevent transmission of, and infection with, antimicrobial-resistant healthcare-associated pathogens. We describe the basis for pathogen reduction as an overall prevention strategy, the evidence for its effectiveness, and the role of the human microbiome in colonization resistance that also reduces the risk for infection once colonized. In addition, we explore ideal attributes of current and future pathogen-reducing approaches.

Introduction of 7-day amotosalen/ultraviolet A light pathogen-reduced platelets in Honduras: Impact on platelet availability in a lower middle-income country.

BACKGROUND AND OBJECTIVES: Honduras became the first lower middle-income country (LMIC) to adopt amotosalen/UVA pathogen-reduced (PR) platelet concentrates (PCs) as a national platelet safety measure in 2018. The Honduran Red Cross (HRC) produces ~70% of the national platelet supply using the platelet-rich plasma (PRP) method. Between 2015 and 2018, PCs were screened with bacterial culture and issued as individual, non-pooled PRP units with weight-based dosing and 5-day shelf-life. PR PCs were produced in six-PRP pools with a standardized dose (≥3.0 × 1011), no bacterial screening and 7-day shelf-life. Gamma irradiation and leukoreduction were not used. MATERIALS AND METHODS: PC production and distribution data were retrospectively analysed in two periods. Period 1 (P1) included 3 years of PRP PCs and a transition year (2015-18). Period 2 (P2) included 5 years of PR PCs (2019-23). PC doses were standardized to an equivalent adult dose for both periods. Descriptive statistics were calculated. RESULTS: HRC produced 10% more PC doses per year on average in P2 compared to P1. Mean annual waste at HRC declined from 23.9% in P1 to 1.1% in P2. Two urban regions consumed 96% of PC doses in P1 and 88.3% in P2. PC distributions increased in 14/18 regions. CONCLUSION: Standardized dosage, PR and 7-day shelf-life increased PC availability, reduced waste, eliminated bacterial screening and avoided additional costs for arboviral testing, leukoreduction and irradiation. Access to PC transfusion remains limited in Honduras; however, the conversion to pooled PR PCs illustrates the potential to sustainably expand PC distribution in an LMIC.

Implementation of amotosalen plus ultraviolet A-mediated pathogen reduction for all platelet concentrates in France: Impact on the risk of transfusion-transmitted infections.

BACKGROUND AND OBJECTIVES: Pathogen reduction (PR) technology may reduce the risk of transfusion-transmitted infections (TTIs), notably transfusion-transmitted bacterial infection (TTBI) associated with platelet concentrates (PCs). PR (amotosalen/UVA treatment) was implemented for all PCs transfused in France in November 2017. No bacterial detection was in place beforehand. The study aimed to assess the impact of PR PC on TTI and TTBI near-miss occurrences. MATERIALS AND METHODS: TTI and TTBI near-miss occurrences were compared before and after 100% PR implementation. The study period ran from 2013 to 2022. Over 300,000 PCs were transfused yearly. RESULTS: No PC-related transmission of human immunodeficiency virus, hepatitis C virus, hepatitis B virus and human T-cell lymphotropic virus was reported throughout the study period. PC-mediated hepatitis E virus and hepatitis A virus infections occurred irrespective of PR implementation. Mean PC-mediated TTBI occurrence before PR-PC implementation was 3/year (SD: 1; n = 15; 1/92,687 PC between 2013 and 2016) with a fatal outcome in two patients. Since PR implementation, one TTBI has been reported (day 4 PC, Bacillus cereus) (1/1,645,295 PC between 2018 and 2022; p < 0.001). Two PR PC quarantined because of a negative swirling test harboured bacteria: a day 6 PC in 2021 (B. cereus and Staphylococcus epidermidis) and a day 7 PC in 2022 (Staphylococcus aureus). Five similar occurrences with untreated PC were reported between 2013 and 2020. CONCLUSION: Transfusion of 100% PR PC resulted in a steep reduction in TTBI occurrence. TTBI may, however, still occur. Pathogen-reduced PC-related TTI involving non-enveloped viruses occurs as well.

Therapeutic efficacy and safety of pathogen-reduced platelet components: Results of a meta-analysis of randomized controlled trials.

BACKGROUND AND OBJECTIVES: Clinical efficacy and safety of pathogen-reduced platelet concentrates (PR-PCs) concerning bleeding prevention are still debated despite conclusive real-world data from multiple countries where PR-PCs are transfused routinely. We performed a meta-analysis of randomized controlled trials (RCTs) comparing the clinical efficacy and safety of conventional platelet components (PCs) and PR-PCs prepared with the amotosalen/ultraviolet A light (INTERCEPT platelet concentrate [I-PC]) or riboflavin/ultraviolet light (Mirasol platelet concentrate [M-PC]) technologies, transfused in thrombocytopenic adult patients. MATERIALS AND METHODS: A literature search was conducted, and 10 RCTs met the criteria for inclusion in this meta-analysis. Summary odds ratios (ORs) of clinically significant bleeding (World Health Organization [WHO] bleeding grade ≥2), severe bleeding (WHO bleeding score ≥3) and all-cause mortality were calculated. RESULTS: The use of I-PC was not associated with an increase in the OR of clinically significant bleeding when compared to non-treated PCs (OR, 1.12; 95% CI: 0.89-1.41; p = 0.33), whereas transfusions with M-PC showed an increase in clinically significant bleeding (OR, 1.34; 95% CI: 1.03-1.75; p = 0.03). The OR of severe bleeding did not increase with either I-PC or M-PC (OR 0.88; 95% CI: 0.59-1.31; p = 0.52 for I-PC; OR 1.25; 95% CI: 0.66-2.37; p = 0.49 for M-PC). In the case of all-cause mortality, compared to non-treated PC, I-PC showed an OR of 0.61 (95% CI: 0.36-1.04; p = 0.07), and M-PC showed an OR of 3.04 (95% CI: 0.81-11.47; p = 0.1). CONCLUSION: No differences were observed concerning the clinical efficacy and safety of overall PR-PCs when compared to non-treated PCs. However, differences are evident when analysing platelets prepared with the two PR technologies independently.

Dose-dependent inactivation of Plasmodium falciparum in red blood cell concentrates by treatment with short-wavelength ultraviolet light.

BACKGROUND AND OBJECTIVES: Plasmodium species are naturally transmitted by Anopheles mosquitos. The parasite infects red blood cells (RBCs) and can be transfused with blood products. In non-endemic areas, the main risk of infection arises from travellers coming back and people immigrating from malaria-endemic regions. Endemic countries face a permanent risk of infection from transfusion-transmitted malaria (TTM). TTM may cause life-threatening complications in patients dependent on blood donations. This study aimed to investigate the efficacy of Plasmodium falciparum inactivation in RBC units by treatment with short-wavelength ultraviolet C (UVC) light in the absence of photochemical additives. MATERIALS AND METHODS: RBC units were spiked with P. falciparum to a parasite density of 0.1%-1% and irradiated with up to 4.5 J/cm2 UVC. The parasite density of UVC-treated dilution series and untreated controls were compared over 3 weeks after irradiation. RESULTS: The lowest dose of 1.5 J/cm2 UVC led to a 3.1 log reduction in parasite load compared with the untreated control. The inactivation capacity was dose-dependent. Strikingly, 4.5 J/cm2 led to ≥5.3 log unit reduction, which was equivalent to a complete inactivation in two out of three experiments. CONCLUSION: Pathogen reduction with UVC light was previously shown to be effective for different bacteria and viruses, but the inactivation of parasites in RBC concentrates was not addressed until now. The present study provides evidence for significant inactivation of P. falciparum-infected RBCs by UVC light.

Spectroscopic view on the interaction between the psoralen derivative amotosalen and DNA.

Psoralens are eponymous for PUVA (psoralen plus UV-A radiation) therapy, which inter alia can be used to treat various skin diseases. Based on the same underlying mechanism of action, the synthetic psoralen amotosalen (AMO) is utilized in the pathogen reduction technology of the INTERCEPT® Blood System to inactivate pathogens in plasma and platelet components. The photophysical behavior of AMO in the absence of DNA is remarkably similar to that of the recently studied psoralen 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT). By means of steady-state and time-resolved spectroscopy, intercalation and photochemistry of AMO and synthetic DNA were studied. AMO intercalates with a higher affinity into A,T-only DNA (KD = 8.9 × 10-5 M) than into G,C-only DNA (KD = 6.9 × 10-4 M). AMO covalently photobinds to A,T-only DNA with a reaction quantum yield of ΦR = 0.11. Like AMT, it does not photoreact following intercalation into G,C-only DNA. Femto- and nanosecond transient absorption spectroscopy reveals the characteristic pattern of photobinding to A,T-only DNA. For AMO and G,C-only DNA, signatures of a photoinduced electron transfer are recorded.

Evaluation of riboflavin concentrations and light intensities on bacteria reduction in platelets using visible light.

Bacterial contamination in platelets has been a major concern over the years. In this study, we showed that treatment with 420 nm visible light with various concentrations of riboflavin in platelets reduced E. coli and S. aureus by 0-1.56 and 0.3-2.02 logs (50 mW/cm2), 2.24-4.77 and 0.73-3.26 logs (75 mW/cm2), and ≥ 5.14 and ≥ 5.27 logs (100 mW/cm2). Treatment with high-intensity light (100 mW/cm2) and high concentrations of riboflavin (400 µM and 500 µM) effectively reduced both bacteria in platelets by over 4 logs. The study also found a positive correlation between bacterial reduction and light intensity, as well as riboflavin concentration in a dose-dependent manner. These results demonstrate the potential of using riboflavin and visible light to reduce the risk of bacterial contamination in platelets, and support the need for further exploration of pathogen reduction using 420 nm visible light and riboflavin.

Metabolomics evaluation of the photochemical impact of violet-blue light (405 nm) on ex vivo platelet concentrates.

INTRODUCTION: Microbicidal violet-blue light in the visible spectrum (405 nm) has been under evaluation for pathogen inactivation in ex vivo human plasma and platelets (PLTs) stored in plasma. Results to date have demonstrated that several blood-borne infectious disease-causing pathogens can be successfully reduced to significantly low levels in the light-treated plasma and PLTs. METHOD: In order to evaluate whether the microbicidal 405 nm light is safe for the treatment of PLT concentrates for pathogen inactivation, LC/MS-based metabolomics analyses were performed to evaluate the overall impact of 405 nm violet-blue light treatment on ex vivo PLT concentrates suspended in plasma and on plasma itself, and to identify metabolome changes in intra-platelet and extra-cellular medium (i.e., plasma). RESULTS: The metabolomics data identified that platelet activating factors (PAFs), agonists and prostaglandins, which can influence PLT basic functions such as integrity, activation, and aggregation potential were unaltered, suggesting that 405 nm light illumination is safe regarding PLT basic functions. Distinct increases in hydroxyl fatty acids and aldehydes, as well as decreases in antioxidant metabolites indicated that reactive oxygen species (ROS) were generated at high levels after only one hour of exposure to 405 nm light. Distinctly changed endogenous photosensitizer metabolites after 1 h of light exposure provided good evidence that 405 nm light was an effective microbicide acting through ROS mechanism and no external additive photosensitizers were required.

Risk of HLA antibody generation after receipt of Mirasol versus standard platelets in the MIPLATE randomized trial.

BACKGROUND: Human leukocyte antigen (HLA) alloimmunization can occur after platelet transfusion. These antibodies can complicate future platelet transfusions or organ transplantation. Animal data suggest that Mirasol pathogen reduction treatment (PRT) can prevent alloimmunization after transfusion. STUDY DESIGN AND METHODS: The MIPLATE trial enrolled 330 of a planned 660 participants with hematological malignancies at risk for grade 2 or greater bleeding. The study was halted early for futility after a planned interim analysis. Participants were randomized to receive PRT versus standard control platelets. Serum samples were collected from participants at baseline (pretransfusion), weekly for the first 4 weeks, then at days 42 and 56. HLA antibody levels were determined using a commercial multianalyte bead-based assay. HLA antibody levels were analyzed using low, medium, and high cutoffs based on prior studies. RESULTS: The rate of alloimmunization was low in both arms of the study, particularly at the high HLA antibody cutoff (total of 6 of 277 subjects at risk, or 2.2%). The risk of alloimmunization did not differ between study arms, nor did the risk of immune refractoriness to platelet transfusion. CONCLUSIONS: The data do not support the conclusion that Mirasol exerted a protective effect against alloimmunization after platelet transfusion in the MIPLATE trial.

Evaluating the inventory impact of utilizing low titer platelets in regional hospitals.

BACKGROUND: As a result of constrained supply, it is sometimes necessary to provide patients with ABO-mismatched platelets. Such practices increase the risk of acute hemolytic transfusion reaction (AHTR). Providing patients with platelets suspended in O plasma having low-titer Anti-A and Anti-B antibodies (LtABO) could reduce the incidence of AHTR. However, natural scarcity limits the number of such units that can be produced. In this paper we present a study to evaluate strategies for deploying LtABO at regional hospitals in Canada. STUDY DESIGN AND METHODS: Regional hospitals often experience demand for platelets on an irregular basis. They are, however, required to stock some number of platelets (typically one A-unit and one O-unit) for emergencies; outdates are common, with discard rates sometimes >>50%. A simulation study was completed to determine the impact of replacing a (1A, 1O) inventory with 2 or 3 units of LtABO at regional hospitals. RESULTS: A significant decreases in wastage and shortage can be expected by replacing a (1A, 1O) inventory policy with 2 units of LtABO. In tested cases, a 2-unit LtABO dominated a (1A, 1O) policy, resulting in statistically fewer outdates and instances of shortage. Holding 3 units of LtABO, increases product availability, but results in an increase in outdates when compared to a (1A, 1O) policy. CONCLUSION: Providing LtABO platelets to smaller, regional hospitals will lower wastage rates and improve patient access to care, when compared to existing (1A, 1O) inventory policies.

Longitudinal analysis of annual national hemovigilance data to assess pathogen reduced platelet transfusion trends during conversion to routine universal clinical use and 7-day storage.

BACKGROUND: France converted to universal pathogen reduced (PR; amotosalen/UVA) platelets in 2017 and extended platelet component (PC) shelf-life from 5- to 7-days in 2018 and 2019. Annual national hemovigilance (HV) reports characterized longitudinal PC utilization and safety over 11 years, including several years prior to PR adoption as the national standard of care. METHODS: Data were extracted from published annual HV reports. Apheresis and pooled buffy coat [BC] PC use was compared. Transfusion reactions (TRs) were stratified by type, severity, and causality. Trends were assessed for three periods: Baseline (2010-14; ~7% PR), Period 1 ([P1] 2015-17; 8%-21% PR), and Period 2 ([P2] 2018-20; 100% PR). RESULTS: PC use increased by 19.1% between 2010 and 2020. Pooled BC PC production increased from 38.8% to 68.2% of total PCs. Annual changes in PCs issued averaged 2.4% per year at baseline, -0.02% (P1) and 2.8% (P2). The increase in P2 coincided with a reduction in the target platelet dose and extension to 7-day storage. Allergic reactions, alloimmunization, febrile non-hemolytic TRs, immunologic incompatibility, and ineffective transfusions accounted for >90% of TRs. Overall, TR incidence per 100,000 PCs issued declined from 527.9 (2010) to 345.7 (2020). Severe TR rates declined 34.8% between P1-P2. Forty-six transfusion-transmitted bacterial infections (TTBI) were associated with conventional PCs during baseline and P1. No TTBI were associated with amotosalen/UVA PCs. Infections with Hepatitis E (HEV) a non-enveloped virus resistant to PR, were reported in all periods. DISCUSSION: Longitudinal HV analysis demonstrated stable PC utilization trends with reduced patient risk during conversion to universal 7-day amotosalen/UVA PCs.

Plasma transfusion-transmission of Zika virus in mice and macaques.

BACKGROUND: Zika virus (ZIKV) epidemics with infections in pregnant women are associated with severe neurological disease in newborns. Although an arbovirus, ZIKV is also blood transfusion-transmitted (TT). Greater knowledge of the efficiency of ZIKV TT would aid decisions on testing and pathogen reduction technologies (PRT). STUDY DESIGN AND METHODS: Plasma units from ZIKV RNA-reactive blood donors were used to study infectivity in vitro, in mice, and in macaques. Furthermore, plasma units were subjected to PRT using amotosalen/ultraviolet light A (A/UVA) before transfusion. RESULTS: In vitro infectivity of ZIKV RNA-reactive plasma varied between 100 and 1000 international units (IU) of ZIKV RNA. Immunodeficient mice were more sensitive with as low as 32 IU sufficient to infect 50% of mice. 50-5500 IU of RNA led to TT in macaques using dose escalation of three different RNA-positive, seronegative plasma units. In contrast, RNA-reactive units collected postseroconversion were not infectious in macaques, even at a dose of 9 million IU RNA. After A/UVA PRT, transfusion of plasma containing up to 18 million IU was no longer infectious in vitro and did not result in ZIKV TT in macaques. CONCLUSION: Significant risks of ZIKV TT are likely confined to a relatively short viremic window before seroconversion, and that sensitive nucleic acid amplification testing likely identifies the majority of infectious plasma. PRT was demonstrated to be effective at preventing ZIKV TT. Considering that there is no approved ZIKV vaccine, these data are relevant to mitigate the risk of TT during the future ZIKV outbreaks.

Assessment of the impact of pathogen reduction technologies on the neutralizing activity of COVID-19 convalescent plasma.

COVID-19 convalescent plasma (CCP) could improve the clinical outcome of COVID-19 patients when high-titer CCP is administered in early stages of disease. However, CCP donors have a risk profile like first-time donors, pathogen reduction treatment (PRT) may mitigate such risk but should not impact CCP quality. The current study aims to assess the impact of PRT-technologies available in Saudi Arabia on the neutralizing activity of CCP. STUDY DESIGN: and Methods: CCP was collected from eligible donors by plasmapheresis. The neutralization titer was determined with an in-house microneutralization assay (MNA) using a local SARS-CoV-2 clinical isolate. Selected units were split and subject to PRT with amotosalen/UVA (AS) or Riboflavin/UVB (RB) (pairwise side-by-side comparison) followed by a second MNA analysis. 51 CCP units were collected, 27 were included in the analysis reaching the minimum MNA titer of 1:40 (4 reached high titer (≥1:250)). 27 CCP units were treated with AS and 14 with RB, the median MNA pre-treatment titer was 1:80 (1:40-640). The impact of AS and RB PRT on CCP neutralizing activity was not significantly different, nor in the total analysis neither in the pairwise comparison (94.6 vs 96.4 % retention, p > 0.05). No correlation of titer and blood group was observed, but a trend for increasing MNA titer with donor age, choosing donors with an age > 45 years would increase the number of high-titer CCP donors. The difference in impact of AS and RB on CCP MNA titer was below the limit of detection of the assay (0.5-fold).

Effect of mirasol pathogen reduction technology system on immunomodulatory molecules of apheresis platelets.

Pathogen inactivation for platelets by riboflavin system (MIRASOL) efficiently reduces transfusion related pathogen transmission. However little is known about its impact on platelets' immunomodulatory biochemical profile. We aimed was to assess the effects of MIRASOL treatment on platelet quality parameters and immunomodulatory molecules CD62P, RANTES, and CD40L in Single Donor Platelets (SDPs) resuspended in plasma (SDP-P) or T-PAS and additive solution (SDP-A). Twenty nine SDPs (15 SDP-P and 14 SDP-A) were included in the study. Samples were collected before, after MIRASOL treatment and just before transfusion. P-selectin (CD62P), RANTES, and CD40L were tested by ELISA. Platelet products quality assays were also performed. Platelet count/unit decreased after Mirasol treatment by 13 %. The pH of all units decreased over the 5-day storage period but remained above expected limits and the swirling test was positive throughout storage. P-selectin levels were not different between the three different time points in both SDPs-P and SDPs-A while RANTES levels were found to differ statistically significantly at the three different time points in all units and in the SPD-A subgroup. CD40L levels in all SDP products increased slightly during storage but this was not statistically significant. CD62P, RANTES, and CD40L in all time points were elevated in SDPs-A compared to SDPs-P but not at a statistically significant level. In conclusion MIRASOL treatment apart from RANTES increase does not seem to substantially affect platelets associated other cytokines and immunomodulatory molecules namely P-selectin and sCD40L which are implicated in immune transfusion reactions.

The Impact of Pathogen Reduction on Total IgG and IgG Subclass Profiles of Convalescent Plasma.

Introduction: In case of newly emerging pathogens, convalescent plasma (CP) is often the only early available treatment option. It has been shown that different IgG subclasses contribute differently to CP neutralizing activity. As CP donors often have a risk profile like first-time donors, especially with respect to window-period viral transmission, pathogen reduction (PR) could mitigate that risk. The aim of our study, especially in the light of potential future pandemics, was to evaluate the impact of commercially available PR technologies on total IgG and IgG subclasses quantity and distribution in CP using COVID-19 CP (CCP) as surrogate for CP in a side-by-side comparison approach. Methods: 36 apheresis CCP donations were allocated to three study groups and a side-by-side assessment of the potential impact of amotosalen (AS)/UVA treatment compared to a riboflavin (RB)/UVB treatment, AS against methylene blue (MB) treatment, and RB against MB treatment on the quantity of IgG and IgG subclasses with a nephelometric analyzer was performed. Results: IgG subclass distributions were not significantly changed post PR treatment with all three technologies. There was also no significant difference in the median loss of concentration for IgG1 and IgG2 between the three technologies. We recognized a non-significant trend of a higher IgG4 median loss post RB treatment compared to post AS and MB treatment, respectively. Conclusion: Although the three commercially available PR systems do not significantly alter the distribution of IgG subclasses, we detected a non-significant trend of higher IgG4 loss after RB treatment. The potential impact of that finding needs further investigation.

Transfusion outcomes between regular and low yield pathogen reduced platelets across different patient populations in a single institution.

BACKGROUND: Pathogen reduction technology (PRT) effectively mitigates bacterial contamination in platelets but is more likely to produce low yield units. Although low dose transfusion using conventional platelets has not been associated with increased bleeding, these findings have not been reproduced with PRT-treated platelets. STUDY DESIGN AND METHODS: Platelet transfusions in a tertiary adult hospital were retrospectively reviewed. Comparisons were made between PRT-treated regular (PRT-PR) and low (PRT-PL) yield platelets. Outcomes examined included the number of platelets and RBCs transfused, transfusion-free interval, and corrected count increment (CCI). Subgroup analyses were also performed on hematology-oncology inpatients and outpatients, as well as non-hematology-oncology patients. RESULTS: Platelet utilization per patient remained mostly unchanged (mean 2.9-4.3 units per patient per month) even when the frequency of PRT-PL transfusion increased. Among 1402 patients examined, the number of platelets and RBCs transfused was not significantly different between patients first transfused with PRT-PR versus PRT-PL (mean number of platelet units = 2.8 vs. 3.1, p = 0.38; mean number of RBC units = 4.8 vs. 4.3, p = 0.93). Among 10,257 platelet transfusions examined, the transfusion-free interval (hazard ratio = 1.05, 95% confidence interval 1.00-1.10) and CCI (10.2 vs. 11.0, p = 0.70) were comparable between PRT-PR and PRT-PL units. Similar findings were observed in all subgroups, except for shortened transfusion-free intervals among hematology-oncology inpatients. CONCLUSION: PRT-PR and PRT-PL units may be used in an equivalent manner to maintain an adequate platelet inventory, since there was only a minor difference in time between transfusions.

Impact of different pathogen reduction technologies on the biochemistry, function, and clinical effectiveness of platelet concentrates: An updated view during a pandemic.

Standard platelet concentrates (PCs) stored at 22°C have a limited shelf life of 5 days. Because of the storage temperature, bacterial contamination of PCs can result in life-threatening infections in transfused patients. The potential of blood components to cause infections through contaminating pathogens or transmitting blood-borne diseases has always been a concern. The current safety practice to prevent pathogen transmission through blood transfusion starts with a stringent screening of donors and regulated testing of blood samples to ensure that known infections cannot reach transfusion products. Pathogen reduction technologies (PRTs), initially implemented to ensure the safety of plasma products, have been adapted to treat platelet products. In addition to reducing bacterial contamination, PRT applied to PCs can extend their shelf life up to 7 days, alleviating the impact of their shortage, while providing an additional safety layer against emerging blood-borne infectious diseases. While a deleterious action of PRTs in quantitative and qualitative aspects of plasma is accepted, the impact of PRTs on the quality, function, and clinical efficacy of PCs has been under constant examination. The potential of PRTs to prevent the possibility of new emerging diseases to reach cellular blood components has been considered more hypothetical than real. In 2019, a coronavirus-related disease (COVID-19) became a pandemic. This episode should help when reconsidering the possibility of future blood transmissible threats. The following text intends to evaluate the impact of different PRTs on the quality, function, and clinical effectiveness of platelets within the perspective of a developing pandemic.

Robust inactivation of Plasmodium falciparum in red blood cell concentrates using amustaline and glutathione pathogen reduction.

BACKGROUND: Plasmodium falciparum is the parasite responsible for most malaria cases globally. The risk of transfusion-transmitted malaria (TTM) is mitigated by donor deferrals and blood screening strategies, which adversely impact blood availability. Previous studies showed robust inactivation of P. falciparum using nucleic acid-targeting pathogen reduction technologies (PRT) for the treatment of plasma and platelet components or whole blood (WB). The efficacy of the amustaline-glutathione (GSH) PRT to inactivate P. falciparum is here evaluated in red blood cells (RBC), as well the impact of PRT on parasite loads, stages, and strains. STUDY DESIGN AND METHODS: RBC units resuspended in AS-1 or AS-5 additive solutions were spiked with ring stage-infected RBC and treated with the amustaline-GSH PRT. Parasite loads and viability were measured in samples at the time of contamination, and after treatment, using serial 10-fold dilutions of the samples in RBC cultures maintained for up to 4 weeks. RESULTS: P. falciparum viability assays allow for the detection of very low levels of parasite. Initial parasite titer was >5.2 log10 /ml in AS-1/5 RBC. No infectious parasites were detected in amustaline-GSH-treated samples after 4 weeks of culture. Amustaline-GSH inactivated high parasite loads regardless of parasite stages and strains. Amustaline readily penetrates the parasite, irreversibly blocks development, and leads to parasite death and expulsion from RBC. DISCUSSION: Amustaline-GSH PRT demonstrated robust efficacy to inactivate malaria parasites in RBC concentrates. This study completes the portfolio of studies demonstrating the efficacy of nucleic acid-targeting PRTs to mitigate TTM risks as previously reported for platelet concentrates, plasma, and WB.

New ultraviolet C light-based method for pathogen inactivation of red blood cell units.

BACKGROUND: Pathogen inactivation (PI) technologies for platelet concentrates and plasma are steadily becoming more established, but new PI treatment options for red blood cells (RBCs), the most commonly used blood component, still need to be developed. We present a novel approach to inactivating pathogens in RBC units employing ultraviolet C (UVC) light. METHODS: Whole blood-derived leukoreduced RBCs suspended in PAGGS-C, a third generation additive solution, served as test samples, and RBCs in PAGGS-C or SAG-M as controls. Vigorous agitation and hematocrit reduction by diluting the RBCs with additional additive solution during illumination ensured that UVC light penetrated and inactivated the nine bacteria and eight virus species tested. Bacterial and viral infectivity assays and in vitro analyses were performed to evaluate the system's PI capacity and to measure the RBC quality, metabolic, functional, and blood group serological parameters of UVC-treated versus untreated RBCs during 36-day storage. RESULTS: UVC treatment of RBCs in the PAGGS-C additive solution did not alter RBC antigen expression, but significantly influenced some in vitro parameters. Compared to controls, hemolysis was higher in UVC-treated RBC units, but was still below 0.8% at 36 days of storage. Extracellular potassium increased early after PI treatment and reached ≤70 mmol/L by the end of storage. UVC-treated RBC units had higher glucose and 2,3-diphosphoglycerate levels than controls. CONCLUSION: As UVC irradiation efficiently reduces the infectivity of relevant bacteria and viruses while maintaining the quality of RBCs, the proposed method offers a new approach for PI of RBC concentrates.

Optimization of human platelet lysate production and pathogen reduction in a public blood transfusion center.

BACKGROUND: Human platelet lysate (HPL) has been proposed as a safe and efficient xeno-free alternative to fetal bovine serum (FBS) for large-scale culturing of cell-based medicinal products. However, the use of blood derivatives poses a potential risk of pathogen transmission. To mitigate this risk, different pathogen reduction treatment (PRT) practices can be applied on starting materials or on final products, but these methods might modify the final composition and the quality of the products. STUDY DESIGN AND METHODS: We evaluated the impact of applying a PRT based on riboflavin and ultraviolet irradiation on the raw materials used to manufacture an improved Good Manufacturing Practices (GMP)-grade HPL product in a public blood center. Growth promotion and the levels of growth factors and proteins were compared between an inactivated product (HPL4-i) and a non-inactivated product (HPL4). Stability studies were performed at 4°C, -20°C, and -80°C. RESULTS: The application of a PRT on the starting materials significantly altered the protein composition of HPL4-i as compared with HPL4. Despite this, the growth promoting rates were unaffected when compared with FBS used as a control. While all products were stable at -20°C and -80°C for 24 months, a significant decrease in the activity of HPL4-i was observed when stored at 4°C. CONCLUSION: Our results show that the application of a PRT based on riboflavin and ultraviolet light on starting materials used in the manufacture of HPL modifies the final composition of the product, yet its cell growth promoting activity is maintained at levels similar to those of non-inactivated products.