Hemodilution Increases the Susceptibility of Red Blood Cells to Mechanical Shear Stress During In Vitro Hemolysis Testing

Study on Differential Metabolite Active Ingredients in Maize Roots Based on Network Pharmacology and Metabolomics Analysis

Maize is a globally important crop. Roots are the main part of maize and are mainly used for soil improvement and for maintaining crop growth as agricultural waste. Their application scope is relatively small. It is very important to analyze the components in maize roots in order to increase their resource utilization and reduce the burden of waste disposal. Metabolomics shows that maize roots contain various bioactive components, such as alkaloids, phenolic acids, flavonoids, etc. Therefore, this study explores the potential pharmacological effects of maize root metabolites under drought stress from the perspective of metabolomics combined with network pharmacology. The crude extraction of betaine, a metabolite in maize roots under drought stress, was conducted, and the anti-inflammatory and antioxidant effects of the crude extract were evaluated. The experimental results of DPPH, Fenton, etc. indicate that the crude extract of betaine from maize roots has certain anti-inflammatory and antioxidant effects, which provides a basis for its potential applications in the fields of medicine and food. The research on extracting medicinal active substances such as betaine from maize roots as agricultural waste not only has economic and environmental advantages but also has important significance in promoting technological progress and public health.

Mechanical Stimulation of Red Blood Cells Aging: Focusing on the Microfluidics Application

Human red blood cells (RBCs) are highly differentiated cells, essential in almost all physiological processes. During their circulation in the bloodstream, RBCs are exposed to varying levels of shear stress ranging from 0.1-10 Pa under physiological conditions to 50 Pa in arterial stenotic lesions. Moreover, the flow of blood through splenic red pulp and through artificial organs is associated with brief exposure to even higher levels of shear stress, reaching up to hundreds of Pa. As a result of this exposure, some properties of the cytosol, the cytoskeleton, and the cell membrane may be significantly affected. In this review, we aim to systematize the available information on RBC response to shear stress by focusing on reported changes in various red cell properties. We pay special attention to the results obtained using microfluidics, since these devices allow the researcher to accurately simulate blood flow conditions in the capillaries and spleen.

Hemolysis during open heart surgery in patients with hereditary spherocytosis - systematic review of the literature and case study

BACKGROUND

Due to the distinctive nature of cardiac surgery, patients suffering from hereditary spherocytosis (HS) are potentially at a high risk of perioperative complications resulting from hemolysis. Despite being the most prevalent cause of hereditary chronic hemolysis, the standards of surgical management are based solely on expert opinion.

OBJECTIVE

We analyze the risk of hemolysis in HS patients after cardiac surgery based on a systematic review of the literature. We also describe a case of a patient with hereditary spherocytosis who underwent aortic valve repair.

METHODS

This systematic review was registered in the PROSPERO international prospective register of systematic reviews (CRD42023417666) and included records from Embase, MEDLINE, Web of Science, and Google Scholar databases. The case study investigates a 38-year-old patient who underwent surgery for an aortic valve defect in mid-2022.

RESULTS

Of the 787 search results, 21 studies describing 23 cases of HS undergoing cardiac surgery were included in the final analysis. Hemolysis was diagnosed in five patients (one coronary artery bypass graft surgery, two aortic valve bioprosthesis, one ventricular septal defect closure, and one mitral valve plasty). None of the patients died in the perioperative period. Also, no significant clinical hemolysis was observed in our patient during the perioperative period.

CONCLUSIONS

The literature data show that hemolysis is not common in patients with HS undergoing various cardiac surgery techniques. The typical management of a patient with mild/moderate HS does not appear to increase the risk of significant clinical hemolysis. Commonly accepted beliefs about factors inducing hemolysis during cardiac surgery may not be fully justified and require further investigation.

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.

Hemocompatibility challenge of membrane oxygenator for artificial lung technology

The artificial lung (AL) technology is one of the membrane-based artificial organs that partly augments lung functions, i.e. blood oxygenation and CO₂ removal. It is generally employed as an extracorporeal membrane oxygenation (ECMO) device to treat acute and chronic lung-failure patients, and the recent outbreak of the COVID-19 pandemic has re-emphasized the importance of this technology. The principal component in AL is the polymeric membrane oxygenator that facilitates the O₂/CO₂ exchange with the blood. Despite the considerable improvement in anti-thrombogenic biomaterials in other applications (e.g., stents), AL research has not advanced at the same rate. This is partly because AL research requires interdisciplinary knowledge in biomaterials and membrane technology. Some of the promising biomaterials with reasonable hemocompatibility - such as emerging fluoropolymers of extremely low surface energy - must first be fabricated into membranes to exhibit effective gas exchange performance. As AL membranes must also demonstrate high hemocompatibility in tandem, it is essential to test the membranes using in-vitro hemocompatibility experiments before in-vivo test. Hence, it is vital to have a reliable in-vitro experimental protocol that can be reasonably correlated with the in-vivo results. However, current in-vitro AL studies are unsystematic to allow a consistent comparison with in-vivo results. More specifically, current literature on AL biomaterial in-vitro hemocompatibility data are not quantitatively comparable due to the use of unstandardized and unreliable protocols. Such a wide gap has been the main bottleneck in the improvement of AL research, preventing promising biomaterials from reaching clinical trials. This review summarizes the current state-of-the-art and status of AL technology from membrane researcher perspectives. Particularly, most of the reported in-vitro experiments to assess AL membrane hemocompatibility are compiled and critically compared to suggest the most reliable method suitable for AL biomaterial research. Also, a brief review of current approaches to improve AL hemocompatibility is summarized. STATEMENT OF SIGNIFICANCE: The importance of Artificial Lung (AL) technology has been re-emphasized in the time of the COVID-19 pandemic. The utmost bottleneck in the current AL technology is the poor hemocompatibility of the polymer membrane used for O₂/CO₂ gas exchange, limiting its use in the long-term. Unfortunately, most of the in-vitro AL experiments are unsystematic, irreproducible, and unreliable. There are no standardized in-vitro hemocompatibility characterization protocols for quantitative comparison between AL biomaterials. In this review, we tackled this bottleneck by compiling the scattered in-vitro data and suggesting the most suitable experimental protocol to obtain reliable and comparable hemocompatibility results. To the best of our knowledge, this is the first review paper focusing on the hemocompatibility challenge of AL technology.

In vitro assessment of the direct hemolytic effect of the volatile halogenated anesthetics sevoflurane, isoflurane, and desflurane

Sevoflurane is being repurposed as a topical analgesic for painful wounds. Providing pre-charged sevoflurane syringes to irrigate wounds implies a potential risk of accidental intravenous injections. We assessed the potential of two concentrations (33% and 50% v/v) of three anesthetics, isoflurane, desflurane and sevoflurane, to produce hemolysis in vitro. Spectrophotometric absorbance was read at 576 nm. For both concentrations, the percentage of hemolysis (mean ± SD) was higher for isoflurane (29.7 ± 3.4% and 39.5 ± 5.3%), mild for desflurane (8.0 ± 0.5% and 6.5 ± 0.9%) and negligible for sevoflurane (0.7 ± 0.0% and 0.6 ± 0.1%), respectively. In conclusion, in contrast to isoflurane and desflurane, sevoflurane did not display hemolytic potential in vitro. However, the use of syringes preloaded with sevoflurane may still be problematic if it increases the possibility of inadvertent intravenous administration through increased risk of gas embolism and severe central nervous system depression.

Hemolysis Testing In Vitro: A Review of Challenges and Potential Improvements

Many medical devices such as cardiopulmonary bypass systems, mechanical heart valves, or ventricular assist devices are intended to come into contact with blood flow during use. In vitro hemolysis testing can provide valuable information about the hemocompatibility of prototypes and thus help reduce the number of animal experiments required. Such tests play an important role as research and development tools for objective comparisons of prototypes and devices as well as for the extrapolation of their results to clinical outcomes. Therefore, it is important to explore and provide new ways to improve current practices. In this article, the main challenges of hemolysis testing are described, namely the difficult blood sourcing, the high experimental workload, and the low reproducibility of test results. Several approaches to address the challenges identified are proposed and the respective literature is reviewed. These include the replacement of blood as the "shear-sensitive fluid" by alternative test fluids, the replacement of sparse, manual sampling and blood damage assessment by a continuous and automated monitoring, as well as an analysis of categories and causes of variability in hemolysis test results that may serve as a structural template for future studies.

Potential Factors for Poor Reproducibility of In Vitro Hemolysis Testing

In vitro testing of hemolysis is essential for the validation and development of ventricular assist devices. However, as many factors influence hemolysis, such tests' inter- and intralaboratory reproducibility is poor. In this work, CentriMag blood pumps were used to conduct a hemolysis study according to ASTM F1841 with blood from 23 bovine donors. Complementary blood analysis, including cell count, plasma composition, and viscosity, was performed to identify factors relevant to the variability of hemolysis testing results. Three strategies were tested to improve reproducibility: albumin supplementation, maintaining glucose concentration, and replacement of plasma with plasma-like buffer. Differences in red blood cell stability among donors were responsible for the largest portion of the total variance. Hematocrit varied widely among donors, and its adjustment to a standard value led to the artificial introduction of between-donor differences, especially in viscosity. It seems likely, that a more careful selection of donors with similar characteristics or repeated blood collection from the same donor could improve reproducibility. However, no direct correlations were found between the susceptibility to hemolysis and individual donor or blood characteristics in this study. The addition of albumin and glucose had a negligible effect while washing blood samples with artificial plasma significantly reduced mean hemolysis, although not its variation. The findings contribute to the understanding of variability in hemolysis experiments and give reason to question the common standard operating procedures, such as hemodilution or maintaining glucose concentration. To confirm the factors identified here, additional studies isolating the effects of individual factors are necessary.

Extracorporeal Membrane Oxygenation-Induced Hemolysis: An In Vitro Study to Appraise Causative Factors

In vitro hemolysis testing is commonly used to determine hemocompatibility of ExtraCorporeal Membrane Oxygenation (ECMO). However, poor reproducibility remains a challenging problem, due to several unidentified influencing factors. The present study investigated potential factors, such as flow rates, the use of anticoagulants, and gender of blood donors, which could play a role in hemolysis. Fresh human whole blood was anticoagulated with either citrate (n = 6) or heparin (n = 12; 6 female and 6 male blood donors). Blood was then circulated for 360 min at 4 L/min or 1.5 L/min. Regardless of flow rate conditions, hemolysis remained unchanged over time in citrated blood, but significantly increased after 240 min circulation in heparinized blood (p ≤ 0.01). The ratio of the normalized index of hemolysis (NIH) of heparinized blood to citrated blood was 11.7-fold higher at 4 L/min and 16.5–fold higher at 1.5 L/min. The difference in hemolysis between 1.5 L/min and 4 L/min concurred with findings of previous literature. In addition, the ratio of NIH of male heparinized blood to female was 1.7-fold higher at 4 L/min and 2.2-fold higher at 1.5 L/min. Our preliminary results suggested that the choice of anticoagulant and blood donor gender could be critical factors in hemolysis studies, and should be taken into account to improve testing reliability during ECMO.