A perspective on exogenous redox regulation mediated by transfused RBCs subject to the storage lesion

Granted with a potent ability to interact with and tolerate oxidative stressors, RBCs scavenge most reactive oxygen and nitrogen species (RONS) generated in circulation. This essential non-canonical function, however, renders RBCs susceptible to damage when vascular RONS are generated in excess, making vascular redox imbalance a common etiology of anemia, and thus a common indication for transfusion. This accentuates the relevance of impairments in redox metabolism during hypothermic storage, as the exposure to chronic oxidative stressors upon transfusion could be exceedingly deleterious to stored RBCs. Herein, we review the prominent mechanisms of the hypothermic storage lesion that alter the ability of RBCs to scavenge exogenous RONS as well as the associated clinical relevance.

Advancing in vivo assessment of red blood cell transfusions: A call for radiation-free methods in transfusion medicine

RBC transfusions are a vital clinical therapy to treat anemic patients. The in vivo assessment of red blood cell (RBC) quality post-transfusion is critical to ensuring that the introduction of new RBC products meet established regulatory and clinical quality requirements. Although in vitro quality control testing is routinely performed by blood manufacturers, it is crucial that in vivo tests are performed during the evaluation and regulatory process of new RBC products. This article reviews existing in vivo techniques, like chromium-51 labelling and biotinylation, for determining the circulation and survival of RBCs, and advocates for a move to radiation-free methods. The timely need for radiation-free methods to assess emerging non-DEHP container systems is just one example of why efforts to improve the methods available for in vivo quality assessment is important in transfusion medicine. This review aims to advance our understanding of RBC transfusion in vivo quality assessment and enhance transfusion practices.

Modification of deglycerolization procedure improves processing and post-thaw quality of cryopreserved sickle trait red cell concentrates

Red blood cell (RBC) transfusion is a critical therapy for those with sickle cell disease (SCD). Alloimmunization is frequent for those with SCD and may limit the availability of matched RBC. Cryopreserved RBCs, from family members or donors with a similar RBC antigen profile could provide a viable alternative to avoid further alloimmunization and prevent hemolytic transfusion-related events. However, cryopreserved SCD and Sickle Cell trait (S-trait) donor RBC units suffer from reduced recovery following deglycerolization. This study proposes and tests a modified deglycerolization protocol using an automated cell processor to mitigate RBC loss. Six red cell concentrates (RCC) from donors with S-trait and six control RCCs were glycerolized, frozen (<-65 °C) and deglycerolized on the ACP 215 using modified parameters (decreased hypertonic solution flow rate (100 mL/min) and hypertonic equilibration delay (120 s), and increased NaCl dilution volumes (500 mL). Quality testing included: hematocrit (HCT), hemolysis, indices, extracellular potassium, morphology, osmotic fragility, osmotic gradient ektacytometry, hemoglobin (HGB), and recovery. Canadian standards (CS) indicate that acceptable deglycerolized units for transfusion require a HCT ≤0.80 L/L, HGB ≥35 g/unit, and hemolysis <0.8 % in 90 % of units tested. No significant differences in HGB or RBC recovery were observed between study groups. Significant differences between study groups were identified in osmotic fragility and osmotic gradient ektacytometry parameters. Of the 6 S-trait RCCs, 3/6 units were within the HCT, HGB and hemolysis thresholds set by the CS. The modified deglycerolization protocol provides a path for the routine cryopreservation of S-trait RBCs.

Red cell concentrates from teen male donors contain poor-quality biologically older cells

BACKGROUND AND OBJECTIVES

Donor factors influence the quality characteristics of red cell concentrates (RCCs) and the lesions that develop in these heterogeneous blood products during hypothermic storage. Teen male donors' RCCs contain elevated levels of biologically old red blood cells (RBCs). The aim of this study was to interrogate the quality of units of different donor ages and sexes to unravel the complex interplay between donor characteristics, long-term cold storage and, for the first time, RBC biological age.

MATERIALS AND METHODS

RCCs from teen males, teen females, senior males and senior females were density-separated into less-dense/young (Y-RBCs) and dense/old RBCs (O-RBCs) throughout hypothermic storage for testing. The unseparated and density-separated cells were tested for haematological parameters, stress (oxidative and osmotic) haemolysis and oxygen affinity (p50).

RESULTS

The O-RBCs obtained from teen donor samples, particularly males, had smaller mean corpuscular volumes and higher mean corpuscular haemoglobin concentrations. While biological age did not significantly affect oxygen affinity, biologically aged O-RBCs from stored RCCs exhibited increased oxidative haemolysis and decreased osmotic fragility, with teenage male RCCs exhibiting the highest propensity to haemolyse.

CONCLUSION

Previously, donor age and sex were shown to have an impact on the biological age distribution of RBCs within RCCs. Herein, we demonstrated that RBC biological age, particularly O-RBCs, which are found more prevalently in male teens, to be a driving factor of several aspects of poor blood product quality. This study emphasizes that donor factors should continue to be considered for their potential impacts on transfusion outcomes.

Estimated median density identifies donor age and sex differences in red blood cell biological age

BACKGROUND

Donors possess heterogeneous red cell concentrates (RCCs) in terms of the biological age of their red blood cells (RBCs) as a direct result of various donor-dependent factors influencing rates of erythropoiesis. This study aimed to estimate the median biological age of RBCs in RCCs based on donor age and sex to investigate inherent differences in blood products' biological ages over hypothermic storage using estimated median densities (EMDs).

STUDY DESIGN

Sixty RCCs were collected from four donor groups; male and female teenagers (17-19 years old) and seniors (75+ years old). A Percoll density-based separation approach was used to quantify the EMDs indicative of biological age. EMD and mean corpuscular hemoglobin (MCHC) were compared by correlation analyses.

RESULTS

Differences in the median biological age of RCC units were observed with male donors having significantly higher EMDs compared to females (p < .001). Teen male donors possessed the highest EMDs with significantly elevated levels of biologically aged RBCs compared to both female donor groups, regardless of storage duration (p < .05). Throughout most of the 42-day storage period, senior donors, particularly senior females, demonstrated the strongest correlation between EMD and MCHC (R2 > 0.5).

CONCLUSIONS

This study provides further evidence that there are inherent differences between the biological age profiles of RBCs between blood donors of different sex and age. Our findings further highlight that biological age may contribute to RBC quality during storage and that donor characteristics need to be considered when evaluating transfusion safety and efficacy.

Transforming research to improve therapies for trauma in the twenty-first century

Improvements have been made in optimizing initial care of trauma patients, both in prehospital systems as well as in the emergency department, and these have also favorably affected longer term outcomes. However, as specific treatments for bleeding are largely lacking, many patients continue to die from hemorrhage. Also, major knowledge gaps remain on the impact of tissue injury on the host immune and coagulation response, which hampers the development of interventions to treat or prevent organ failure, thrombosis, infections or other complications of trauma. Thereby, trauma remains a challenge for intensivists. This review describes the most pressing research questions in trauma, as well as new approaches to trauma research, with the aim to bring improved therapies to the bedside within the twenty-first century.

Towards the crux of sex-dependent variability in red cell concentrates

Donor sex can alter the RBC 'storage lesion' progression, contributing to dissimilarities in blood product quality, and thus adverse post-transfusion reactions. The mechanisms underlying the reduced sensitivity of female RBCs to storage-induced stress are partially ascribed to the differential effects of testosterone, progesterone, and estrogen on hemolytic propensity. Contributing to this is the increased proportion of more robust, biologically 'young' subpopulations of RBCs in females. Herein, we discuss the impact of sex hormones on RBCs and the relevance of these biological subpopulations to provide further insight into sex-dependent blood product variability.

Transfusion of female blood in a rat model is associated with red blood cells entrapment in organs

Transfusion of red blood cells (RBCs) has been associated with adverse outcomes. Mechanisms may be related to donor sex and biological age of RBC. This study hypothesized that receipt of female blood is associated with decreased post-transfusion recovery (PTR) and a concomitant increased organ entrapment in rats, related to young age of donor RBCs. Donor rats underwent bloodletting to stimulate production of new, young RBCs, followed by Percoll fractionation for further enrichment of young RBCs based on their low density. Control donors did not undergo these procedures. Male rats received either a (biotinylated) standard RBC product or a product enriched for young RBCs, derived from either male or female donors. Controls received saline. Organs and blood samples were harvested after 24 hours. This study found no difference in PTR between groups, although only the group receiving young RBCs from females failed to reach a PTR of 75%. Receipt of both standard RBCs and young RBCs from females was associated with increased entrapment of donor RBCs in the lung, liver, and spleen compared to receiving blood from male donors. Soluble ICAM-1 and markers of hemolysis were higher in recipients of female blood compared to control. In conclusion, transfusing RBCs from female donors, but not from male donors, is associated with trapping of donor RBCs in organs, accompanied by endothelial activation and hemolysis.

Risk factors for T-cell lymphopenia in frequent platelet donors: The BEST collaborative study

BACKGROUND

Severe T-cell lymphopenia of uncertain clinical significance has been observed in frequent apheresis platelet donors. Two commonly used plateletpheresis instruments are the Trima Accel, which uses a leukoreduction system (LRS) chamber to trap leukocytes and the Fenwal Amicus, which does not use an LRS chamber.

STUDY DESIGN AND METHODS

We performed an international, multicenter, observational study comparing T-cell populations in frequent platelet donors collected exclusively using the Trima instrument (n = 131) or the Amicus instrument (n = 77). Age- and sex-matched whole blood donors (n = 126) served as controls.

RESULTS

CD4+ T-cell counts <200 cells/μL were found in 9.9% of frequent Trima (LRS+) platelet donors, 4.4% of frequent Amicus (LRS-) platelet donors, and 0 whole blood donors (p < .0001). CD4+ T-cell counts <200 cells/μL were only seen in platelet donors with ≥200 lifetime donations. In multivariable analysis, age, lifetime donations, and instrument (Trima vs. Amicus) were independent risk factors for lymphopenia. In 40 Trima platelet donors, a plasma rinseback procedure was routinely performed following platelet collections. No Trima platelet donors receiving plasma rinseback had a CD4+ T-cell count <200 cells/μL versus 13/91 Trima platelet donors not receiving plasma rinseback (p = .01).

DISCUSSION

Recurrent bulk lymphocyte removal appears to contribute to the development of T-cell lymphopenia in frequent, long-term platelet donors. Lymphopenia is more common when an LRS chamber is used during platelet collection but can occur without an LRS chamber. Blood centers using LRS chambers can mitigate donor lymphopenia by performing plasma rinseback.

Multinational comparison study of aircraft pilot healthcare avoidance behaviour

BACKGROUND

US and Canadian pilots are required to meet medical standards to secure their active flying status, but a subgroup exhibit healthcare avoidance behaviour due to fear of loss of that status. This phenomenon has the potential to impact pilot health, aeromedical screening and aviation safety. No international comparison study of pilot healthcare avoidance currently exists between US and Canadian pilots.

AIMS

To compare the rate and subtypes of healthcare avoidance behaviour secondary to fear for loss of flying status between US and Canadian pilots.

METHODS

A comparison analysis of data collected during two independent, non-probabilistic, cross-sectional internet surveys including any individual certified to perform flying duties in the USA (US survey) or Canada (Canadian survey).

RESULTS

There were 4320 US pilots and 1415 Canadian pilots who completed informed consent and 3765 US pilots and 1405 Canadian pilots were included in the results. There were 56% of US pilots who reported a history of healthcare avoidance behaviour compared to 55% of Canadian pilots (P = 0.578). A multivariable logistic regression that included age, pilot type and gender showed that US pilots were slightly more likely than Canadian pilots to report this behaviour (odds ratio 1.22, 95% confidence interval 1.06-1.4).

CONCLUSIONS

Healthcare avoidance behaviour due to fear of loss of flying status has a relatively high prevalence in both US and Canadian pilot populations.

Extracellular vesicles: effectors of transfusion-related acute lung injury

Respiratory transfusion reactions represent some of the most severe adverse reactions related to receiving blood products. Of those, transfusion-related acute lung injury (TRALI) is associated with elevated morbidity and mortality. TRALI is characterized by severe lung injury associated with inflammation, pulmonary neutrophil infiltration, lung barrier leak, and increased interstitial and airspace edema that cause respiratory failure. Presently, there are few means of detecting TRALI beyond clinical definitions based on physical examination and vital signs or preventing/treating TRALI beyond supportive care with oxygen and positive pressure ventilation. Mechanistically, TRALI is thought to be mediated by the culmination of two successive proinflammatory hits, which typically comprise a recipient factor (1st hit-e.g., systemic inflammatory conditions) and a donor factor (2nd hit-e.g., blood products containing pathogenic antibodies or bioactive lipids). An emerging concept in TRALI research is the contribution of extracellular vesicles (EVs) in mediating the first and/or second hit in TRALI. EVs are small, subcellular, membrane-bound vesicles that circulate in donor and recipient blood. Injurious EVs may be released by immune or vascular cells during inflammation, by infectious bacteria, or in blood products during storage, and can target the lung upon systemic dissemination. This review assesses emerging concepts such as how EVs: 1) mediate TRALI, 2) represent targets for therapeutic intervention to prevent or treat TRALI, and 3) serve as biochemical biomarkers facilitating TRALI diagnosis and detection in at-risk patients.

Assessment of stored red blood cells through lab-on-a-chip technologies for precision transfusion medicine

Transfusion of red blood cells (RBCs) is one of the most valuable and widespread treatments in modern medicine. Lifesaving RBC transfusions are facilitated by the cold storage of RBC units in blood banks worldwide. Currently, RBC storage and subsequent transfusion practices are performed using simplistic workflows. More specifically, most blood banks follow the "first-in-first-out" principle to avoid wastage, whereas most healthcare providers prefer the "last-in-first-out" approach simply favoring chronologically younger RBCs. Neither approach addresses recent advances through -omics showing that stored RBC quality is highly variable depending on donor-, time-, and processing-specific factors. Thus, it is time to rethink our workflows in transfusion medicine taking advantage of novel technologies to perform RBC quality assessment. We imagine a future where lab-on-a-chip technologies utilize novel predictive markers of RBC quality identified by -omics and machine learning to usher in a new era of safer and precise transfusion medicine.

Quality assessment of red blood cell concentrates from blood donors at the extremes of the age spectrum: The BEST collaborative study

BACKGROUND

Blood donors at the extremes of the age spectrum (16-19 years vs. ≥75 years) are characterized by increased risks of iron deficiency and anemia, and are often underrepresented in studies evaluating the effects of donor characteristics on red blood cells (RBC) transfusion effectiveness. The aim of this study was to conduct quality assessments of RBC concentrates from these unique age groups.

STUDY DESIGN

We characterized 150 leukocyte-reduced (LR)-RBCs units from 75 teenage donors, who were matched by sex, and ethnicity with 75 older donors. LR-RBC units were manufactured at three large blood collection centers in the USA and Canada. Quality assessments included storage hemolysis, osmotic hemolysis, oxidative hemolysis, osmotic gradient ektacytometry, hematological indices, and RBC bioactivity.

RESULTS

RBC concentrates from teenage donors had smaller (9%) mean corpuscular volume and higher (5%) RBC concentration compared with older donors counterparts. Stored RBCs from teenage donors exhibited increased susceptibility to oxidative hemolysis (>2-fold) compared with RBCs from older donors. This was observed at all testing centers independent of sex, storage duration, or the type of additive solution. RBCs from teenage male donors had increased cytoplasmatic viscosity and lower hydration compared with older donor RBCs. Evaluations of RBC supernatant bioactivity suggested that donor age was not associated with altered expression of inflammatory markers (CD31, CD54, and IL-6) on endothelial cells.

CONCLUSIONS

The reported findings are likely intrinsic to RBCs and reflect age-specific changes in RBC antioxidant capacity and physical characteristics that may impact RBC survival during cold storage and after transfusion.

Engineered Compounds to Control Ice Nucleation and Recrystallization

One of the greatest concerns in the subzero storage of cells, tissues, and organs is the ability to control the nucleation or recrystallization of ice. In nature, evidence of these processes, which aid in sustaining internal temperatures below the physiologic freezing point for extended periods of time, is apparent in freeze-avoidant and freeze-tolerant organisms. After decades of studying these proteins, we now have easily accessible compounds and materials capable of recapitulating the mechanisms seen in nature for biopreser-vation applications. The output from this burgeoning area of research can interact synergistically with other novel developments in the field of cryobiology, making it an opportune time for a review on this topic.

Comparing two extracellular additives to facilitate extended storage of red blood cells in a supercooled state

Background: Adenosine triphosphate (ATP) levels guide many aspects of the red blood cell (RBC) hypothermic storage lesions. As a result, efforts to improve the quality of hypothermic-stored red cell concentrates (RCCs) have largely centered around designing storage solutions to promote ATP retention. Considering reduced temperatures alone would diminish metabolism, and thereby enhance ATP retention, we evaluated: (a) whether the quality of stored blood is improved at -4°C relative to conventional 4°C storage, and (b) whether the addition of trehalose and PEG400 can enhance these improvements. Study Design and Methods: Ten CPD/SAGM leukoreduced RCCs were pooled, split, and resuspended in a next-generation storage solution (i.e., PAG3M) supplemented with 0-165 mM of trehalose or 0-165 mM of PEG400. In a separate subset of samples, mannitol was removed at equimolar concentrations to achieve a fixed osmolarity between the additive and non-additive groups. All samples were stored at both 4°C and -4°C under a layer of paraffin oil to prevent ice formation. Results: PEG400 reduced hemolysis and increased deformability in -4°C-stored samples when used at a concentration of 110 mM. Reduced temperatures did indeed enhance ATP retention; however, in the absence of an additive, the characteristic storage-dependent decline in deformability and increase in hemolysis was exacerbated. The addition of trehalose enhanced this decline in deformability and hemolysis at -4°C; although, this was marginally alleviated by the osmolarity-adjustments. In contrast, outcomes with PEG400 were worsened by these osmolarity adjustments, but at no concentration, in the absence of these adjustments, was damage greater than the control. Discussion: Supercooled temperatures can allow for improved ATP retention; however, this does not translate into improved storage success. Additional work is necessary to further elucidate the mechanism of injury that progresses at these temperatures such that storage solutions can be designed which allow RBCs to benefit from this diminished rate of metabolic deterioration. The present study suggests that PEG400 could be an ideal component in these solutions.

CD71+ RBCs: A potential immune mediator in transfusion

Donor - recipient sex - mismatched transfusion is associated with increased mortality. The mechanisms for this are not clear, but it may relate to transfusion-related immunomodulation. Recently, CD71⁺ erythroid cells (CECs), including reticulocytes (CD71⁺ RBCs) and erythroblasts, have been identified as potent immunoregulatory cells. The proportion of CD71⁺ RBCs in the peripheral blood is sufficient to play a potential immunomodulatory role. Differences in the quantity of CD71⁺ RBCs are dependent on blood donor sex. The total number of CD71⁺ RBCs in red cell concentrates is also affected by blood manufacturing methods, and storage duration. As a component of the total CECs, CD71⁺ RBCs can affect innate and adaptive immune cells. Phagocytosed CECs directly reduce TNF-α production from macrophages. CECs can also suppress the production of TNF-α production from antigen presenting cells. Moreover, CECs can suppress T cell proliferation thorough immune mediation and / or direct cell-to-cell interactions. Different in their biophysical features compared to mature RBCs, blood donor CD71⁺ RBCs may be preferential targets for the macrophages. This report summarizes the currently literature supporting an important role for CD71⁺ RBCs in adverse transfusion reactions including immune mediation and sepsis.

Effect of Donor Sex on Recipient Mortality in Transfusion

BACKGROUND

Conflicting observational evidence exists regarding the association between the sex of red-cell donors and mortality among transfusion recipients. Evidence to inform transfusion practice and policy is limited.

METHODS

In this multicenter, double-blind trial, we randomly assigned patients undergoing red-cell transfusion to receive units of red cells from either male donors or female donors. Patients maintained their trial-group assignment throughout the trial period, including during subsequent inpatient and outpatient encounters. Randomization was conducted in a 60:40 ratio (male donor group to female donor group) to match the historical allocation of red-cell units from the blood supplier. The primary outcome was survival, with the male donor group as the reference group.

RESULTS

A total of 8719 patients underwent randomization before undergoing transfusion; 5190 patients were assigned to the male donor group, and 3529 to the female donor group. At baseline, the mean (±SD) age of the enrolled patients was 66.8±16.4 years. The setting of the first transfusion was as an inpatient in 6969 patients (79.9%), of whom 2942 (42.2%) had been admitted under a surgical service. The baseline hemoglobin level before transfusion was 79.5±19.7 g per liter, and patients received a mean of 5.4±10.5 units of red cells in the female donor group and 5.1±8.9 units in the male donor group (difference, 0.3 units; 95% confidence interval [CI], -0.1 to 0.7). Over the duration of the trial, 1141 patients in the female donor group and 1712 patients in the male donor group died. In the primary analysis of overall survival, the adjusted hazard ratio for death was 0.98 (95% CI, 0.91 to 1.06).

CONCLUSIONS

This trial showed no significant difference in survival between a transfusion strategy involving red-cell units from female donors and a strategy involving red-cell units from male donors. (Funded by the Canadian Institutes of Health Research; iTADS ClinicalTrials.gov number, NCT03344887.).

Cultured CD71+ erythroid cells modulate the host immune response

OBJECTIVE

The study aimed to determine the impact of Red Blood Cells (RBCs) generated from peripheral blood mononuclear cells (PBMCs) on T cell proliferation and host response following whole blood stimulation.

BACKGROUND

Culturing RBCs is a potential solution for donor shortage. The impact of immature cultured RBCs which express CD71⁺ on host immune response is not known.

METHODS/MATERIALS

PBMCs were seeded in an erythroid expansion medium. CD71⁺ cells were isolated at days 14 and 21 of culture and incubated with either purified T cells or with LPS-stimulated whole blood. Controls were incubated with medium.

RESULTS

At day 9, the percentage of cells that expressed CD45 and CD71 reached to the highest level (32.9%, IQR; 26.2-39.05) while the percentage of cells that expressed CD71 and CD235a reached to the highest level on day 17 (70.2%, IQR; 66.1-72.8). Incubation of T cells with days 14 CD71⁺ cells and day 21 CD71⁺ cells increased T cell proliferation. In a whole blood stimulation assay, day 21 CD71⁺ cells, but not day 14 CD71⁺ cells, inhibited the production of IL-6 and TNFα.

CONCLUSION

Cultured erythroid cells can modulate the immune response by promoting T cell proliferation and inhibiting cytokine secretions following whole blood stimulation.

The impact of biological age of red blood cell on in vitro endothelial activation markers

Introduction: Blood donor characteristics influence red blood cell transfusion outcomes. As donor sex affects the distribution of young to old RBCs in the circulation, we hypothesized that the amount of circulating young RBCs in the blood product are associated with immune suppression.

Materials and Methods: Blood samples were collected from healthy volunteers and density fractionated into young and old subpopulations. In an activated endothelial cell model, RBC adhesion to endothelium and secretion of endothelial activation markers were assessed. The impact of RBC biological age was also assessed in a T cell proliferation assay and in a whole blood stimulation assay.

Results: After Percoll fractionation, young RBCs contained more reticulocytes compared to old RBCs. Young RBCs associated with lower levels of E-selectin, ICAM-1, and vWF from activated endothelial cells compared to old RBCs. RBC subpopulations did not affect T cell proliferation or cytokine responses following whole blood stimulation.

Conclusion: Young RBCs contain more reticulocytes which are associated with lower levels of endothelial activation markers compared to old RBCs.

Donor sex, pre-donation hemoglobin, and manufacturing affect CD71+ cells in red cell concentrates

BACKGROUND

Circulating CD71⁺ red blood cells (RBCs) have been reported to play an immunomodulatory role in vivo, which may contribute to adverse donor-recipient sex-mismatched transfusion outcomes. However, it is not clear how CD71⁺ RBC quantity in red cell concentrates (RCCs) is affected by manufacturing methods and donor factors such as donor sex, donor age, pre-donation hemoglobin (Hb), venous Hb (Hb_v ) levels, and donation frequency.

METHODS

We determined CD71⁺ RBCs and Hb levels in whole blood (WB) from healthy donors (42 male/38 female). Using small-scale red cell filtration (RCF) and whole blood filtration (WBF) methods, leukoreduced RCCs were processed from WB samples (n = 6) and the CD71⁺ RBCs were determined at days 1, 7, and 28. We examined uni- and multivariate associations among CD71⁺ RBCs, donor factors, and manufacturing method.

RESULTS

Male donors had a higher CD71⁺ RBC concentration than females (p < .001), especially male donors aged 17-50 years with 1 or 2 WB donations over the previous 12 months. Donors with a Hb_v above 155 g/L had a higher CD71⁺ RBC concentration than an Hb_v level below 140 g/L (p < .05). There was a positive correlation between pre-donation Hb and CD71⁺ RBC concentration (Pearson r = 0.41). WBF RCCs had a higher total number of CD71⁺ RBCs than RCF-produced RCCs on day 1 (p < .05).

DISCUSSION

RCCs have variable numbers of CD71⁺ RBCs. This makes understanding the impact of donor factors and manufacturing methods on the immunomodulatory effect of CD71⁺ RBCs critical in exploring donor-recipient sex-mismatched transfusions.

The evaluation of constant coronary artery flow versus constant coronary perfusion pressure during normothermic ex situ heart perfusion

BACKGROUND

Evidence suggests that hearts that are perfused under ex-situ conditions lose normal coronary vasomotor tone and experience contractile failure over a few hours. We aimed to evaluate the effect of different coronary perfusion strategies during ex situ heart perfusion on cardiac function and coronary vascular tone.

METHODS

Porcine hearts (n = 6 each group) were perfused in working mode for 6 hours with either constant aortic diastolic pressure (40 mmHg) or constant coronary flow rate (500 mL/min). Functional and metabolic parameters, cytokine profiles, cardiac and vascular injury, coronary artery function and oxidative stress were compared between groups.

RESULTS

Constant coronary flow perfusion demonstrated better functional preservation and less edema formation (Cardiac index: flow control = 8.33 vs pressure control = 6.46 mL·min^-1·g^-1, p = 0.016; edema formation: 7.92% vs 19.80%, p < 0.0001). Pro-inflammatory cytokines, platelet activation as well as endothelial activation were lower in the flow control group. Similarly, less cardiac and endothelial injury was observed in the constant coronary flow group. Evaluation of coronary artery function showed there was loss of coronary autoregulation in both groups. Oxidative stress was induced in the coronary arteries and was relatively lower in the flow control group.

CONCLUSIONS

A strategy of controlled coronary flow during ex situ heart perfusion provides superior functional preservation and less edema formation, together with less myocardial damage, leukocyte, platelet, endothelial activation, and oxidative stress. There was loss of coronary autoregulation and decrease of coronary vascular resistance during ESHP irrespective of coronary flow control strategy. Inflammation and oxidative stress state in the coronary vasculature may play a role.

Closed system processing variables affect post-thaw quality characteristics of cryopreserved red cell concentrates

BACKGROUND

Differences in manufacturing conditions using the Haemonetics ACP 215 cell processor result in cryopreserved red cell concentrates (RCCs) of varying quality. This work studied the effect of processing method, additive solution, and storage duration on RCC quality to identify an optimal protocol for the manufacture of cryopreserved RCCs.

MATERIALS AND METHODS

RCCs were pooled-and-split and stored for 7, 14, or 21 days before cryopreservation. Units were glycerolized with the ACP 215 using a single or double centrifugation method. After thawing, the RCCs were deglycerolized, suspended in AS-3, SAGM, ESOL, or SOLX/AS-7, and stored for 0, 3, 7, 14, or 21 days before quality testing. Quality assessments included hemoglobin content, hematocrit, hemolysis, adenosine triphosphate (ATP), supernatant potassium, and mean cell volume.

RESULTS

Both glycerolization methods produced RCCs that met regulatory standards for blood quality. Dual centrifugation resulted in higher hemoglobin content, fewer processing alerts, and a shorter deglycerolization time than single centrifugation processing. Units processed with AS-3 and ESOL met regulatory standards when stored for up to 21 days pre-cryopreservation and 21 days post-deglycerolization. However, ESOL demonstrated superior maintenance of ATP over RBCs in AS-3. Some RCCs suspended in SAGM and SOLX exceeded acceptable hemolysis values after 7 days of post-deglycerolization storage regardless of pre-processing storage length.

CONCLUSIONS

When manufacturing cryopreserved RCCs using the ACP 215, dual centrifugation processing with AS-3 or ESOL additive solutions is preferred, with storage periods of up to 21 days both pre-processing and post-deglycerolization.

The Effect of Sex-Mismatched Red Blood Cell Transfusion on Endothelial Cell Activation in Critically Ill Patients

BACKGROUND

Observational studies suggest that sex-mismatched transfusion is associated with increased mortality. Mechanisms driving mortality are not known but may include endothelial activation. The aim of this study is to investigate the effects of sex-mismatched red blood cell (RBC) transfusions on endothelial cell activation markers in critically ill patients.

STUDY DESIGN AND METHODS

In patients admitted to the intensive care unit who received a single RBC unit, blood samples were drawn before (T0), 1 h after (T1), and 24 h after transfusion (T24) for analysis of soluble syndecan-1, soluble intercellular adhesion molecule-1, soluble thrombomodulin (sTM), von Willebrand factor antigen, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNFα). Changes in the levels of these factors were compared between sex-matched and sex-mismatched groups.

RESULTS

Of 69 included patients, 32 patients were in the sex-matched and 37 patients were in the sex-mismatched group. Compared to baseline, sex-matched transfusion was associated with significant reduction in sTM level (p value = 0.03). Between-group comparison showed that levels of syndecan-1 and sTM were significantly higher in the sex-mismatched group compared to the sex-matched group at T24 (p value = 0.04 and 0.01, respectively). Also, TNFα and IL-6 levels showed a statistically marginal significant increase compared to baseline in the sex-mismatched group at T24 (p value = 0.06 and 0.05, respectively), but not in the sex-matched group.

DISCUSSION

Transfusion of a single sex-mismatched RBC unit was associated with higher syndecan-1 and sTM levels compared to transfusion of sex-matched RBC unit. These findings may suggest that sex-mismatched RBC transfusion is associated with endothelial activation.

Effect of cryopreservation on a rare McLeod donor red blood cell concentrate

Units of red blood cell (RBC) concentrates with rare phenotypes are typically not included in method validation studies for cryopreservation processes; rather, they are reserved for patients with rare blood needs. Some rare RBC phenotypes may demonstrate membrane abnormalities, like acanthocytosis as observed for RBCs with the McLeod phenotype, and are specifically banked for these rare attributes; however, the impact that rare RBC phenotypes have on post-thaw quality has not been well studied. To evaluate how a rare RBC phenotype is affected by the cryopreservation process, 4 RBC units, cryopreserved in 1993 using manual methods, were selected for evaluation. These RBCs included one with the McLeod phenotype and three with phenotypes not known to cause significant membrane changes. Post-thaw, an altered deglycerolization protocol, implemented to reduce supernatant glycerol after cryopreservation, was used before processing RBCs on an automated closed system (ACP 215; Haemonetics, Boston, MA) to accommodate the use of a closed system cell processor not available when the RBC units were previously cryopreserved. RBC quality was tested at 24 hours, 7 days, and 14 days post-deglycerolization. Before deglycerolization, an extracted sample from the thawed glycerolized RBC unit was used to obtain genetic material for phenotype confirmation. Genotyping confirmed the McLeod phenotype. When comparing McLeod with non-McLeod units, RBCs from the McLeod donor exhibited acanthocytosis, higher rigidity, and lower morphology scores than RBCs from the non-McLeod units post-deglycerolization. Hemolysis, however, was comparable across all 4 units, meeting regulatory standards. Therefore, McLeod RBCs can withstand cryopreservation, suggesting that units from these donors, glycerolized using older methods, can be deglycerolized using the ACP 215 and stored hypothermically for 14 days. It was also determined that genotyping can be performed on non-leukocyte-reduced cryopreserved RBCs, allowing for confirmation of genetic profiles of donor units banked before the implementation of molecular methods.

Units of red blood cell (RBC) concentrates with rare phenotypes are typically not included in method validation studies for cryopreservation processes; rather, they are reserved for patients with rare blood needs. Some rare RBC phenotypes may demonstrate membrane abnormalities, like acanthocytosis as observed for RBCs with the McLeod phenotype, and are specifically banked for these rare attributes; however, the impact that rare RBC phenotypes have on post-thaw quality has not been well studied. To evaluate how a rare RBC phenotype is affected by the cryopreservation process, 4 RBC units, cryopreserved in 1993 using manual methods, were selected for evaluation. These RBCs included one with the McLeod phenotype and three with phenotypes not known to cause significant membrane changes. Post-thaw, an altered deglycerolization protocol, implemented to reduce supernatant glycerol after cryopreservation, was used before processing RBCs on an automated closed system (ACP 215; Haemonetics, Boston, MA) to accommodate the use of a closed system cell processor not available when the RBC units were previously cryopreserved. RBC quality was tested at 24 hours, 7 days, and 14 days post-deglycerolization. Before deglycerolization, an extracted sample from the thawed glycerolized RBC unit was used to obtain genetic material for phenotype confirmation. Genotyping confirmed the McLeod phenotype. When comparing McLeod with non-McLeod units, RBCs from the McLeod donor exhibited acanthocytosis, higher rigidity, and lower morphology scores than RBCs from the non-McLeod units post-deglycerolization. Hemolysis, however, was comparable across all 4 units, meeting regulatory standards. Therefore, McLeod RBCs can withstand cryopreservation, suggesting that units from these donors, glycerolized using older methods, can be deglycerolized using the ACP 215 and stored hypothermically for 14 days. It was also determined that genotyping can be performed on non-leukocyte–reduced cryopreserved RBCs, allowing for confirmation of genetic profiles of donor units banked before the implementation of molecular methods.

High Sub-Zero Organ Preservation: A Paradigm of Nature-Inspired Strategies

The field of organ preservation is filled with advancements that have yet to see widespread clinical translation, with some of the more notable strategies deriving their inspiration from nature. While static cold storage (SCS) at 2 °C to 4 °C is the current state-of-the-art, it contributes to the current shortage of transplantable organs due to the limited preservation times it affords combined with the limited ability of marginal grafts (i.e. those at risk for post-transplant dysfunction or primary non-function) to tolerate SCS. The era of storage solution optimization to minimize SCS-induced hypothermic injury has plateaued in its improvements, resulting in a shift towards the use of machine perfusion systems to oxygenate organs at normothermic, sub-normothermic, or hypothermic temperatures, as well as the use of sub-zero storage temperatures to leverage the protection brought forth by a reduction in metabolic demand. Many of the rigors that organs are subjected to at low sub-zero temperatures (-80 °C to -196 °C) commonly used for mammalian cell preservation have yet to be surmounted. Therefore, this article focuses on an intermediate temperature range (0 °C to -20 °C), where much success has been seen in the past two decades. The mechanisms leveraged by organisms capable of withstanding prolonged periods at these temperatures through either avoiding or tolerating the formation of ice has provided a foundation for some of the more promising efforts. This article therefore aims to contextualize the translation of these strategies into the realm of mammalian organ preservation.

Copro-polymerase chain reaction has higher sensitivity compared to centrifugal fecal flotation in the diagnosis of taeniid cestodes, especially Echinococcus spp, in canids

Prompt and reliable diagnostic tests for taeniid infection in canids are important due to the risk of zoonoses like Echinococcus spp. Current diagnostic methods relying on fecal flotation lack sensitivity and specificity, but this has rarely been quantified due to the challenges in performing adult cestode recovery (the gold standard) in domestic dogs (Canis familiaris). Therefore, we recovered adult Taenia and Echinococcus spp. from intestines, as well as fecal/intestinal material from 484 wild canids trapped for fur in two Canadian provinces (276 foxes - primarily Vulpes vulpes, coyotes - Canis latrans, and wolves - Canis lupus in Québec and 208 coyotes in Saskatchewan). The performances of a newly developed coproPCR for tapeworm DNA detection in dogs, and centrifugal fecal flotation using Sheather's solution, were evaluated against adult cestode recovery. Overall, adult taeniid cestode prevalence (Taenia and/or Echinococcus) was 28 % (95 % CI: 23-33 %) in Québec (62 % (CI: 51-73%) of 74 coyotes, 65 % (CI: 44-82) of 23 wolves, and 11 % (CI: 7-16%) of 179 foxes) and 79 % (CI: 73-84%) of 208 coyotes in Saskatchewan. In Québec, E. canadensis and Taenia spp. were detected in coyotes and wolves, and foxes were only infected with Taenia spp., whereas Saskatchewan coyotes were predominantly infected with E. multilocularis (at significantly higher prevalence, but not intensity, than coyotes in Québec). Compared with centrifugal fecal flotation, the new coproPCR had at least double the sensitivity (58 % vs 23 % in QC coyotes, 57 % vs 23 % in QC wolves, 24 % vs 0% in QC foxes, and 80 % vs 25 % in SK coyotes). Notably, no taeniid eggs were detected on flotations from foxes infected with Taenia spp., and the new coproPCR had highest sensitivity in Saskatchewan coyotes, which were predominantly infected with E. multilocularis. CoproPCR has promising prospects for use in Veterinary clinics and diagnostic laboratories to detect taeniid cestode infections because of its higher sensitivity than faecal flotation methods. This is particularly important for zoonotic Echinococcus spp. where, from a public health perspective, false negatives are a much greater concern than false positives.

Pragmatic, double-blind, randomised trial evaluating the impact of red blood cell donor sex on recipient mortality in an academic hospital population: the innovative Trial Assessing Donor Sex (iTADS) protocol

INTRODUCTION

With over 1 million units of blood transfused each year in Canada, their use has a significant clinical and economic impact on our health system. Adequate screening of blood donors is important to ensure the safety and clinical benefit of blood products. Some adverse transfusion reactions have been shown to be related to donor factors (eg, lung injury), whereas other adverse outcomes have been theoretically related to donor factors (mortality and infection). Our clinical trial will test whether male donor blood leads to a greater benefit for transfusion recipients compared with female donor blood.

METHODS AND ANALYSIS

We have designed a pragmatic, double-blind, randomised trial that will allocate transfusion recipients to receive either male-only or female-only donor transfusions. We will enrol 8850 adult patients requiring at least one transfusion at four sites over an approximate 2-year period. Randomisation and allocation will occur in the blood bank prior to release of the units of blood for transfusion. Our primary outcome is mortality. An intent-to-treat analysis will be applied using all randomised and transfused patients. The principal analysis will be a survival analysis comparing the time from randomisation to death between patients allocated to male donor red blood cells (RBCs) and female donor RBCs.

ETHICS AND DISSEMINATION

Approval has been obtained from research ethics boards of all involved institutions, as well as from privacy offices of Canadian Blood Services, Institute for Clinical Evaluative Science and The Ottawa Hospital Data Warehouse. Our findings will be published in peer-reviewed journals and presented at relevant stakeholder conferences and meetings.

TRIAL REGISTRATION NUMBER

NCT03344887; Pre-results.

Hypothermic storage of leukoreduced red blood cells for greater than 21 days is a safe alternative to irradiation

BACKGROUND

Irradiation of red blood cells (RBCs) inactivates residual donor T lymphocytes to prevent transfusion-associated graft-vs-host disease (TA-GVHD) but can have adverse effects on recipients and inventory management. Reported incidence of TA-GVHD is lower when leukoreduced RBCs and older blood products are transfused; therefore, the impact of leukoreduction and storage was evaluated as an alternative prevention strategy.

STUDY DESIGN AND METHODS

Effectiveness of leukoreduction filters on white blood cell (WBC) proliferation was evaluated by filtering buffy coat (BC) products and isolating residual WBCs. Additionally, leukoreduced RBCs were spiked with 5 × 10⁶ WBCs on Day 21 of hypothermic storage, then stored and processed on Days 7, 14, and 21 to obtain residual WBCs to investigate the impact of hypothermic storage on their viability and proliferative ability. Viability of residual WBCs was assessed by staining with annexin V and an antibody cocktail for flow cytometry analysis. Proliferative ability was assessed by placing carboxyfluorescein diacetate succinimidyl ester-labeled residual WBCs into culture for 6 days with phytohemagglutinin before flow cytometry assessment.

RESULTS

Filtration of BC units depleted WBCs, particularly T lymphocytes, to 0.001% ± 0.003% cells/unit, although proliferative activity remained consistent with prefiltration levels of WBCs. WBCs in stored RBCs remained viable even on Day 21 of storage; however, the proliferative activity decreased to 0.24% ± 0.41%.

CONCLUSIONS

Hypothermic storage of RBCs for 21 days or more is sufficient to inactivate T lymphocytes, which may help prevent TA-GVHD when irradiated RBCs are not available.

Emerging use of machine learning and advanced technologies to assess red cell quality

Improving blood product quality and patient outcomes is an accepted goal in transfusion medicine research. Thus, there is an urgent need to understand the potential adverse effects on red blood cells (RBCs) during pre-transfusion storage. Current assessment techniques of these degradation events, termed "storage lesions", are subjective, labor-intensive, and complex. Here we describe emerging technologies that assess the biochemical, biophysical, and morphological characteristics of RBC storage lesions. Of these emerging techniques, machine learning (ML) has shown potential to overcome the limitations of conventional RBC assessment methods. Our previous work has shown that neural networks can extract chronological progressions of morphological changes in RBCs during storage without human input. We hypothesize that, with broader training and testing of multivariate data (e.g., varying donor factors and manufacturing methods), ML can further our understanding of clinical transfusion outcomes in multiple patient groups.

Transient loss of membrane integrity following intracellular ice formation in dimethyl sulfoxide-treated hepatocyte and endothelial cell monolayers

Immediate post-thaw evaluation of membrane integrity has proven to yield overestimates of cell survival under conditions that preclude intracellular ice formation (IIF). However, prominent theories on the mechanisms of intracellular nucleation suggest a damaged membrane can reseal, prompting us to evaluate whether immediate post-thaw assessments of membrane integrity can in fact underestimate cell survival under conditions that promote IIF. HUVEC and HepG2 monolayers were treated with 1.4 M DMSO and frozen to -25 °C under conditions that formed either 0% or 100% IIF. Membrane integrity was evaluated both immediately and 24 h post-thaw, with metabolic activity assessments performed 24 h post-thaw as a secondary measure of survival. Treatment with 1.4 M DMSO and nucleation of 100% IIF resulted in a drastic increase in the relative percent of membrane intact cells following a 24 h culture period (HUVEC: 90.2% ± 0.7%; HepG2: 70.4% ± 4.0%), which correlated with 24 h post-thaw metabolic activity. These differences between the immediate and 24 h post-thaw membrane integrity assessments were significantly more than those seen in the absence of either IIF or DMSO treatment. Therefore, a high incidence of IIF in DMSO-treated monolayers may lead to erroneous underestimates of cell survival when conducting immediate post-thaw assessments of membrane integrity.

The efficacy of ice recrystallization inhibitors in rat lung cryopreservation using a low cost technique for ex vivo subnormothermic lung perfusion

Although lung transplant remains the only option for patients with end-stage lung failure, short preservation times result in an inability to meet patient demand. Successful cryopreservation may ameliorate this problem; however, very little research has been performed on lung cryopreservation due to the inability to prevent ice nucleation or growth. Therefore, this research sought to characterize the efficacy of a small-molecule ice recrystallization inhibitor (IRI) for lung cryopreservation given its well-documented ability to control ice growth. Sprague-Dawley heart-lung blocks were perfused at room temperature using a syringe-pump. Cytotoxicity of the IRI was assessed through the subsequent perfusion with 0.4% (w/v) trypan blue followed by formalin-fixation. Ice control was assessed by freezing at a chamber rate of -5 °C/min to -20 °C and cryofixation using a low-temperature fixative. Post-thaw cell survival was determined by freezing at a chamber rate of -5 °C/min to -20 °C and thawing in a 37 °C water bath before formalin-fixation. In all cases, samples were paraffin-embedded, sliced, and stained with eosin. The IRI studied was found to be non-toxic, as cell membrane integrity following perfusion was not significantly different than controls (p = 0.9292). Alveolar ice grain size was significantly reduced by the addition of this IRI (p = 0.0096), and the addition of the IRI to DMSO significantly improved post-thaw cell membrane integrity when compared to controls treated with DMSO alone (p = 0.0034). The techniques described here provide a low-cost solution for rat ex vivo lung perfusion which demonstrated that the ice control and improved post-thaw cell survival afforded by IRI-use warrants further study.

Cryoprotectant-dependent control of intracellular ice recrystallization in hepatocytes using small molecule carbohydrate derivatives

To promote the recovery of cells that undergo intracellular ice formation (IIF), it is imperative that the recrystallization of intracellular ice is minimized. Hepatocytes are more prone to IIF than most mammalian cells, and thus we assessed the ability of novel small molecule carbohydrate-based ice recrystallization inhibitors (IRIs) to permeate and function within hepatocytes. HepG2 monolayers were treated with N-(4-chlorophenyl)-d-gluconamide (IRI 1), N-(2-fluorophenyl)-d-gluconamide (IRI 2), or para-methoxyphenyl-β-D-glycoside (IRI 3) and fluorescent cryomicroscopy was used for real time visualization of intracellular ice recrystallization. Both IRI 2 and IRI 3 reduced rates of intracellular recrystallization, whereas IRI 1 did not. IRI 2 and IRI 3, however, demonstrated a marked reduction in efficiency in the presence of the most frequently used permeating cryoprotectants (CPAs): glycerol, propylene glycol (PG), dimethyl sulfoxide (DMSO), and ethylene glycol (EG). Nevertheless, IRI 3 reduced rates of intracellular recrystallization relative to CPA-only controls in the presence of glycerol, PG, and DMSO. Interestingly, IRI preparation in trehalose, a commonly used non-permeating CPA, did not impact the activity of IRI 3. However, trehalose did increase the activity of IRI 1 while decreasing that of IRI 2. While this study suggests that each of these compounds could prove relevant in hepatocyte cryopreservation protocols where IIF would be prominent, CPA-mediated modulation of intracellular IRI activity is apparent and warrants further investigation.

Control of ice recrystallization in liver tissues using small molecule carbohydrate derivatives

Minimizing ice recrystallization injury in tissues and organs has historically been sought using biological antifreeze proteins. However, the size of these compounds can limit permeation and their potential immunogenicity disqualifies them from use in several cryopreservation applications. Novel small molecule carbohydrate-derived ice recrystallization inhibitors (IRIs) are not subject to these constraints, and thus we sought to evaluate the ability of a highly active IRI to permeate liver tissue and control recrystallization. Rat liver tissue blocks (0.5 mm²) were incubated with the IRI for 6 h at 22 °C and subsequently plunged in liquid nitrogen. Ice crystals within the tissue were fixed using a formal acetic alcohol fixative as it was rewarmed from -80 °C to 22 °C over the course of 48 h. The untreated control demonstrated a gradient of increasing crystal size from the exterior to the interior region of the tissue; however, the IRI-treated condition had no such gradient and exhibited small crystals throughout. Threshold segmentation confirmed a significant reduction in the ice crystal size within the interior region of the IRI-treated condition, suggesting the IRI permeated throughout and effectively controlled recrystallization within the tissue.

Thrombospondin-1/CD47 signaling modulates transmembrane cation conductance, survival, and deformability of human red blood cells

BACKGROUND

Thrombospondin-1 (TSP-1), a Ca²⁺-binding trimeric glycoprotein secreted by multiple cell types, has been implicated in the pathophysiology of several clinical conditions. Signaling involving TSP-1, through its cognate receptor CD47, orchestrates a wide array of cellular functions including cytoskeletal organization, migration, cell-cell interaction, cell proliferation, autophagy, and apoptosis. In the present study, we investigated the impact of TSP-1/CD47 signaling on Ca²⁺ dynamics, survival, and deformability of human red blood cells (RBCs).

METHODS

Whole-cell patch-clamp was employed to examine transmembrane cation conductance. RBC intracellular Ca²⁺ levels and multiple indices of RBC cell death were determined using cytofluorometry analysis. RBC morphology and microvesiculation were examined using imaging flow cytometry. RBC deformability was measured using laser-assisted optical rotational cell analyzer.

RESULTS

Exposure of RBCs to recombinant human TSP-1 significantly increased RBC intracellular Ca²⁺ levels. As judged by electrophysiology experiments, TSP-1 treatment elicited an amiloride-sensitive inward current alluding to a possible Ca²⁺ influx via non-selective cation channels. Exogenous TSP-1 promoted microparticle shedding as well as enhancing Ca²⁺- and nitric oxide-mediated RBC cell death. Monoclonal (mouse IgG1) antibody-mediated CD47 ligation using 1F7 recapitulated the cell death-inducing effects of TSP-1. Furthermore, TSP-1 treatment altered RBC cell shape and stiffness (maximum elongation index).

CONCLUSIONS

Taken together, our data unravel a new role for TSP-1/CD47 signaling in mediating Ca²⁺ influx into RBCs, a mechanism potentially contributing to their dysfunction in a variety of systemic diseases. Video abstract.

Update on newer approaches to prevent or treat COVID-19 infection: What we all need the most right now!!

COVID-19 convalescent plasma (CCP) therapy involves the use of circulating antibodies administration from recovered COVID 19 patients as a practical strategy to provide immediate passive immunity in susceptible recipients in need. Global concern over the potential for “second” or “third” waves of infection to occur before effective vaccines or drug therapies are available has many looking at other biological sources for large-scale production of neutralizing SARS-CoV-2 antibodies. This report summarizes some of the novel strategies for developing alternative safe sources of therapeutic autologous antibodies from COVID ‐19 infected patients, and provides some original thoughts on how to rapidly implement a safe passive immunity in those COVID-19 patients who are most in need of intervention. COVID-19 antibodies can be isolated or delivered using a number of other techniques including: plasmapheresis, plasma cryoprecipitate reduced (cryosupernatant), antibody hyperconcentrates and advanced cell-based delivery systems. While these proposed technological options may, in some cases, be theoretical, the growing concern over the rapid spread of the SARS-CoV-2 virus has prompted many to pursue innovative and creative solutions to reduce the mortality and morbidity resulting from the current global pandemic. A comparative analysis of various strategies currently in use deserved exploring and this highlighted separately as the essential part of this concise theme.

Objective assessment of stored blood quality by deep learning

Stored red blood cells (RBCs) are needed for life-saving blood transfusions, but they undergo continuous degradation. RBC storage lesions are often assessed by microscopic examination or biochemical and biophysical assays, which are complex, time-consuming, and destructive to fragile cells. Here we demonstrate the use of label-free imaging flow cytometry and deep learning to characterize RBC lesions. Using brightfield images, a trained neural network achieved 76.7% agreement with experts in classifying seven clinically relevant RBC morphologies associated with storage lesions, comparable to 82.5% agreement between different experts. Given that human observation and classification may not optimally discern RBC quality, we went further and eliminated subjective human annotation in the training step by training a weakly supervised neural network using only storage duration times. The feature space extracted by this network revealed a chronological progression of morphological changes that better predicted blood quality, as measured by physiological hemolytic assay readouts, than the conventional expert-assessed morphology classification system. With further training and clinical testing across multiple sites, protocols, and instruments, deep learning and label-free imaging flow cytometry might be used to routinely and objectively assess RBC storage lesions. This would automate a complex protocol, minimize laboratory sample handling and preparation, and reduce the impact of procedural errors and discrepancies between facilities and blood donors. The chronology-based machine-learning approach may also improve upon humans' assessment of morphological changes in other biomedically important progressions, such as differentiation and metastasis.

Proliferative and Regenerative Effect of Acetonic Extract of Feijoa sellowiana on Stem Cells

BACKGROUND

Feijoa is widely used in medicine due to their anti-inflammatory, antioxidant, antimicrobial and antitumor properties. The current investigation studied the proliferative and regenerative effect of acetonic extract of Feijoa sellowiana on stem cells.

METHODS

Acetone extract of Feijoa was prepared using percolator and rotary machines. Human bone marrow stem cells (hBMSCs) were used as experimental in vitro model and characterized morphologically, by flowcytometry, and differentiation properties. The toxicity of the extract on hBMSCs was determined by MTT assay. The viability and growth kinetics of hBMSCs treated to Feijoa was determined. Real time PCR was used for changes in expression of proliferative and apoptotic genes on day 7^th.

RESULTS

MTT assay demondtrated that Feijoa at doses less than 200 ng/ml did not show any cytotoxic effect on hBMSCs and increased the cell proliferation until day 3^rd followed by a non-significant slow decreasing trend until day 7^th. Population doubling time (PDT) showed a decline until day 3^rd followed by an increase until day 7^th. A significant rise in expression of Bax and decline in Bcl-2 expression were noted on day 7^th.

CONCLUSION

The modulatory activity of Feijoa may be responsible for its increasing effect on cell proliferation till day 3^rd. Therefore, when faster proliferation during a shorter time period is targeted, Feijoa can be safely added to the culture media in the first three days.