In vitro effects of voxelotor on red blood cell senescence and rheological behavior in sickle cell anemia.

Blood exhibits complex flow behavior governed by red blood cell (RBC) deformation, aggregation, and confinement effects, which are difficult to reproduce in vitro at single-cell level under confinement. Existing blood mimicking fluids (BMFs) primarily replicate bulk rheology but fail to capture microscale single-cell mechanics relevant to microcirculation. Here, we present a particulate blood mimicking fluid (BMF) composed of monodisperse hydrogel-based artificial erythrocytes (ARBC) with a physiological diameter of 9 μm, biconcave geometry, and plasma-phase-dependent mechanical properties. ARBCs are generated using a cross-flow microfluidic fabrication approach, enabling reproducible fabrication and integration into well-defined plasma-phase analogues. Adjustment of the surrounding plasma-phase analogue enabled modulation of particle swelling, elasticity, and interparticle interactions. Under confined microchannel flow, particles exhibited velocity-dependent deformations from disc-like to bullet-like morphologies, reproducing the characteristic trend observed for human RBCs. Depending on the plasma-phase composition, measured deformation indices overlapped with those obtained for RBCs under comparable confinement conditions. By combining physiological geometry, elasticity, and controllable plasma-phase properties, this platform provides a standardized model system for studying microscale hemorheology and for validating deformation-based lab-on-a-chip technologies.

Cancer-associated thrombosis (CAT) remains a leading cause of morbidity and mortality in oncology, reflecting the convergence of tumor-driven hypercoagulability, endothelial dysfunction, and venous stasis. While current models of CAT pathogenesis emphasize tumor-derived procoagulant factors, platelets, and leukocytes, the contribution of red blood cell (RBC) biomechanics has received comparatively limited attention. Emerging evidence indicates that both malignancy and cancer-related therapies impair RBC deformability and increase RBC aggregation; alterations that are known to influence blood viscosity, platelet margination, microvascular flow, and clot contraction. Hence, these alterations have been hypothesized to promote thrombosis, supported by evidence of increased thrombosis risk in diseases that primarily affect RBC biomechanics. While cancer-induced alterations in RBC biomechanics and their role in thrombosis are well-described in non-cancerous conditions, the relationship between altered RBC biomechanics and thrombosis in the setting of cancer has not been thoroughly investigated. Accordingly, this review synthesizes the mechanistic and clinical data linking altered RBC biomechanics to thrombus initiation, propagation, and stability, with particular emphasis on their relationship with established cancer-related prothrombotic pathways such as extracellular vesicle release, neutrophil extracellular trap formation, stasis, and oxidative stress. Finally, we critically assess current CAT risk assessment models (RAMs) and discuss the potential role of RBC biomechanical parameters as dynamic, integrative biomarkers to improve thrombosis risk stratification in cancer patients. Advances in automated and standardized rheological technologies may facilitate the clinical translation of RBC biomechanics, offering new opportunities to refine risk prediction and deepen mechanistic understanding of CAT.

Biomaterials that possess robust tissue adhesion and rapid hemostasis are of great clinical significance in emergency trauma management. Inspired by the adhesive strategy of marine mussels, we developed an adhesive powder (AP) based on sodium carboxymethyl cellulose, acrylic acid, and acrylic acid N-hydroxysuccinimide ester. The powder enables rapid hemostatic sealing, facilitating rapid liquid absorption and excellent wound adaptability. In vitro characterization demonstrated robust tissue adhesion, with an average shear strength of 5947.5 ± 418.8 Pa, an interfacial toughness of 21.1 ± 1.7 J/m2, and a tensile strength of 4450.8 ± 452.0 Pa, along with favorable mechanical properties. AP also exhibited excellent biocompatibility in vitro and in vivo, with high cell viability (>90%), underscoring its potential as a safe hemostatic material. In rat models of liver injury and complete femoral arteriovenous transection, AP significantly reduced blood loss and accelerated hemostasis compared to untreated controls. In addition, in a full-thickness skin wound model, AP promoted wound healing. Furthermore, mechanistic studies revealed that the powder enhanced hemostasis by inducing red blood cell aggregation and activating the intrinsic coagulation pathway. Collectively, the powder is a promising candidate for the treatment of severe bleeding.

To investigate the concurrent physiological response to extreme endurance exercise by examining inflammatory, hemorheological, endothelial, and vascular adaptations following an ultramarathon. Twelve runners (9 men/3 women; 48 ± 7 years) participating in a 230-km non-stop ultramarathon were assessed before and immediately after the race. Systemic inflammatory and oxidative stress markers, indices of red blood cell (RBC) aggregation and fibrinogen, plasma nitrite as a marker of nitric oxide (NO) bioavailability, and macrovascular hemodynamic parameters were measured. White blood cell count (WBC) (p < 0.001), interleukin (IL)-6 (p = 0.0002), IL-10 (p = 0.0002) and C-reactive protein (CRP) (p < 0.001) increased, while plasma free reactive oxygen species (ROS) (p = 0.0043) and total antioxidant capacity (p = 0.0041) decreased post-race. RBC aggregation increased (p = 0.0003) in concert with elevated fibrinogen (p < 0.0001). Plasma nitrite increased post-race (p = 0.0013). Macrovascular hemodynamics exhibited increased heart rate (p < 0.0001) with preserved pulse wave velocity (PWV; p = 0.257) and central pressures. Wave reflection indices were altered, with reduced augmentation index (AIx; p = 0.034), whereas heart rate–standardized AIx75 remained unchanged (p = 0.104), alongside an increase in diastolic reflection area (DRA; p = 0.020) and divergent peripheral pressure responses. The ultramarathon was associated with pronounced inflammatory responses accompanied by increased fibrinogen-related RBC aggregation and elevated plasma nitrite concentrations, while macrovascular properties remained largely preserved. Together, these findings suggest that acute responses to extreme endurance exercise involve parallel inflammatory, hemorheological, endothelial, and macrovascular alterations, with cardiovascular adjustments primarily reflecting functional changes in peripheral vascular regulation rather than substantial changes in central arterial mechanical properties.

A multi-feature alignment fusion neural network model for red blood cell aggregation classification using ultrasonic radiofrequency data of blood.

Scavenger receptor\u2013mediated lung-targeted delivery of anti-miR-155 oligoDNA nanomicelles with curcumin for acute lung injury therapy

Background/Objectives: This study aimed to investigate the effect of pancreatic ductal adenocarcinoma (PDAC) on the alterations in red blood cell aggregation related to angiogenesis and hypoxia markers. Methods: We studied 31 patients with confirmed PDAC. The aggregation of red blood cells (RBCs) was evaluated using a Laser-assisted Optical Rotational Cell Analyzer (LORCA). Serum vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1α (HIF-1α) levels were measured using ELISA. We estimated the following parameters specific to the aggregation process: the aggregation index (AI), the aggregation half-time (t1/2), and the threshold shear rate (γthr). Results: All measured RBC aggregation parameters among PDAC subjects differed from those in the controls. The AI (p < 0.05) and γthr (p < 0.005) were significantly higher in the PDAC group, whereas t1/2 (p < 0.01) and AMP (p < 0.001) were significantly lower compared to the control group. The levels of VEGF (p < 0.0001) and HIF-1α (p < 0.0001) were significantly higher in the PDAC group than in the control group. There were significant correlations between RBC aggregation parameters and VEGF and HIF-1α. Multivariate analyses further identified t1/2 (p < 0.01) and γthr (p < 0.05) as independent predictors for VEGF. For HIF-1α, t1/2 (p < 0.05) was confirmed as an independent predictor. Conclusions: The results suggest, but do not demonstrate, a direct pathophysiological link between PDAC-associated hypoxia/angiogenesis and erythrocyte aggregation. Further studies are needed because the relationship linking PDAC to these aggregation indices is unclear.

HighlightsWhat are the main findings?A microfluidic-based method enabled simultaneous quantification of blood viscosity and RBC aggregation index under continuous blood flow from a driving syringe.Hemorheological properties were strongly affected by experimental factors and thermal shock, which suppressed RBC aggregation and sedimentation.What are the implications of the main findings?The method allows for the reliable evaluation of blood properties under dynamic flow conditions, including syringe on–off operation.The method could be regarded as useful for assessing RBC dysfunction and abnormal hemorheological responses in microfluidic platforms.Accurate assessment of blood viscosity and red blood cell (RBC) aggregation under continuous flow is important for hemorheological analysis. However, simultaneous measurement remains challenging because both properties are influenced by flow conditions and RBC sedimentation. In this study, a microfluidic method is developed for the simultaneous measurement of blood viscosity and RBC aggregation index (AI) during continuous blood delivery from a driving syringe. The proposed device consists of a viscosity-sensing channel for viscosity measurement and aggregation-sensing channel for AI evaluation. The effects of flow rate, hematocrit, suspension medium, and syringe on–off operation are systematically investigated. Blood viscosity and AI are strongly affected by these factors, and transient flow interruption enhances RBC sedimentation in the syringe, thereby altering hemorheological properties. The proposed method is further used to evaluate thermally exposed RBCs, which reduce RBC aggregation and suppress RBC sedimentation when compared with control blood. At higher exposure temperatures and longer exposure times, blood viscosity and AI remain nearly constant over time, indicating minimal contribution of damaged RBCs to RBC sedimentation. These results demonstrate that the proposed method enables reliable simultaneous evaluation of blood viscosity and RBC aggregation and could be regarded as useful for detecting functional alterations of RBCs under continuous-flow conditions.

Sepsis is a life-threatening syndrome characterized by dysregulated immune response to infection and multi-organ dysfunction. One of the key components of this condition is microcirculatory dysfunction. The aim of our study was to evaluate the effects of IgM-enriched immunoglobulin (Pentaglobin, PG) on microcirculation and hemorheological parameters in a porcine model of fulminant sepsis induced by intravenous Escherichia coli (E. coli) suspension. Thirty female juvenile pigs were randomized into four groups: Control, E. coli bacteremia, E. coli + PG parallel, and E. coli + delayed PG. Under anesthesia, the external jugular veins and the right femoral artery were cannulated. The Control group received fluid therapy only. In all sepsis groups, 38 ml of E. coli suspension was administered intravenously over 3 hours. The E. coli + PG parallel group received a 0.75 g/kg Pentaglobin bolus infusion simultaneously with E. coli. The E. coli + delayed PG group received 0.67 g/kg bolus Pentaglobin 1 hour after sepsis induction, followed by a 0.02 g/kg/h maintenance infusion for 4 hours. Microcirculatory assessments were performed before infusion and every 2 hours until hour 6. Hematological parameters, red blood cell (RBC) aggregation, and blood/plasma viscosity were measured. The microvascular flow index reached its highest values in the E. coli + delayed PG group at hour 6 (neck: 2.65 ± 0.23; sublingual: 2.67 ± 0.38). Perfused vessel density was highest in the Control group (sublingual: 1.58 ± 0.39 mm/mm2). Microcirculatory values were worse in the E. coli bacteremia group, indicating marked edema, RBC aggregates, and vascular heterogeneity. E. coli + PG parallel, and E. coli + delayed PG groups showed reduced hematocrit values (p<0.001 vs. baseline) and less pronounced increases in whole blood viscosity and RBC aggregation compared to the E. coli bacteremia group. Fulminant sepsis resulted in severe microcirculatory and hemodynamic disturbances. Pentaglobin therapy mitigated the decline in tissue perfusion, attenuated the elevation of blood viscosity and red blood cell aggregation.

Hemostasis is an important part of surgical operations and trauma and wound care, and it prevents bleeding in three stages: vasoconstriction, platelet plug formation and coagulation. Borate bioglass (BBG) is a biocompatible material used in bone regeneration and repair. In borate bioglass-incorporated hemostasis hydrogels, the clotting process is facilitated by the release of ions such as boron, calcium, and sodium. The ions play a significant role in the coagulation cascade and are important in promoting platelet adhesion. Such hydrogels are biocompatible and biodegradable, which makes them ideal candidates for hemostatic applications. Herein, we synthesized borate bioglass nanoparticles and characterized them by XRD, FTIR spectroscopy, zeta potential measurements, and TEM. Antibacterial investigations demonstrated the good inhibition ability of these nanoparticles against wound pathogens. Blood clotting time analysis, blood clot index, RBC aggregation, PT and aPTT, D dimer assay, platelet aggregation, thrombus weight and hemolysis assay are done for borate bioglass. A BBG-incorporated xanthan hydrogel exhibited a remarkable hemostatic property, as demonstrated by in vivo analysis, with a blood clotting time of 90 s in a liver model, 164 s in a tail amputation model, and 211 s in a femoral artery model.

AimThis study aimed to investigate the effect of pancreatic ductal adenocarcinoma (PDAC) on the RBCs rheological properties at the time of diagnosis and to examine their potential relationship with tumor stage.Material and MethodsWe studied 32 patients with confirmed PDAC.The aggregation and deformability of RBCs were evaluated using a LORCA.The following parameters specific to the aggregation process were estimated: the aggregation index (AI), the aggregation half-time (t1/2), and the threshold shear rate (γthr).RBC deformability expressed as erythrocyte elongation (EI), was measured from 0.3 Pa to 60 Pa shear stresses.ResultsAll measured RBC aggregation parameters among PDAC subjects differed from those in controls. The AI (P < 0.03) was significantly higher in the PDAC group, whereas t1/2 (P < 0.001) and AMP (P < 0.001) were significantly lower compared to the control group. No significant differences in RBC deformability were observed between the PDAC and control groups.There were significant correlations between some RBC aggregation parameters and PDAC tumor staging (T).There was that T correlated positively with t1/2, and negatively with AI and γthr.ConclusionPDAC is associated with alterations in RBC rheology behavior. Results indicated a higher tendency for RBC aggregation and aggregate stability associated with the rigidity of RBC at lower shear stress.

Long COVID is associated with persistent fatigue, exercise intolerance, and microcirculatory dysfunction. Altered red blood cell (RBC) rheology, including impaired deformability and increased aggregation, may contribute to these symptoms, yet the effects of exercise interventions remain unclear. This longitudinal pilot study tested whether an individualized, symptom-responsive exercise program improves RBC rheology in Long COVID. A total of 170 (110 f/60 m) participants entered a five-phase training protocol; 15 completed all phases and formed a predefined finisher subgroup. RBC aggregation and deformability, hematological parameters, and coagulation- and iron-related markers were assessed across phases; RBC morphology was additionally analyzed in finishers at baseline and completion. In the total cohort, aggregation indices decreased across training phases, accompanied by prolonged aggregation half-time, while hematological, coagulation, and iron markers remained largely unchanged. The deformability changes were not uniform in the full cohort; however, finishers showed a deformability shift after completion. Importantly, morphologically abnormal RBC decreased in finishers, and these changes correlated with deformability, suggesting that improved rheology is linked to reduced RBC abnormalities. Prospectively, larger controlled studies are needed to confirm these results and to evaluate whether exercise-induced rheological improvements translate into functional and symptomatic benefits.

For effectively assessing blood, red blood cell (RBC) aggregation and blood viscosity have been measured in microfluidic environments. However, the previous methods still face several challenges (dead-volume loss, RBC sedimentation, hematocrit-sensitive blood velocity, and precise flow rate control). In this study, a novel method is suggested to resolve several issues. Air cavity (Vair = 250 μL) is secured above the blood column (at least 100 μL) loaded into a driving syringe. To probe RBC aggregation and blood viscosity, a microfluidic chip consists of a main channel (γ˙ > 1000 s-1) and an aggregation channel (γ˙ < 50 s-1). Blood is supplied into a microfluidic chip with two-step blood delivery (i.e., air compression for RBC aggregation, and syringe pump for blood viscosity). RBC aggregation index and blood viscosity are obtained from time-lapse image intensity and blood flow rate in both channels. As performance demonstrations, first, the measurement accuracy of fluid viscosity is validated with glycerin solution. Then, the present method is adopted to probe the difference in hematocrit and dextran concentration. At last, the proposed method is employed to detect heat-shocked RBCs (45~50 °C for 40 min). In conclusion, the proposed method has the ability to accurately measure substantial changes in RBCs or blood medium.

Tonicity and colloid osmotic pressure drive microvascular recovery from low volume hypotensive resuscitation from hemorrhagic shock.

ABSTRACT Blood viscosity, which is an important index during the extracorporeal treatment, is one of the determinants of red blood cell aggregation in the blood. In this paper, we propose an optical detection method for red blood cell aggregations by using object detection algorithms, assuming that they will be incorporated into the flow path of an extracorporeal circulation device. By performing detection from a single image, it is a method that can detect aggregations without being affected by rotation, scaling, or the attachment and detachment of red blood cells. In the simulated red blood cell sample, the detectability of aggregations was shown not only at the focus site but also at the defocus site.

Enterohemorrhagic Escherichia coli (EHEC) causes thrombotic microangiopathy, yet the red blood cell (RBC)-centered mechanism has remained unclear. We identify the RTX-family hemolysin EhxA as the driver of RBC-mediated thrombogenesis. Deletion of ehxA abolishes Ca2+ influx, phosphatidylserine (PS) exposure, progression from discocyte to echinocyte to spherocyte, thrombin generation, RBC-endothelium adhesion, and RBC aggregation. Genetic complementation restores these readouts to wild type, and purified EhxA in bacteria-free assays recapitulates them while localizing to intact RBC membranes. By contrast, Δstx2 mutants do not elicit these RBC phenotypes, distinguishing this pathway from Shiga toxin-dependent effects. Multiple regression quantifies the link between PS exposure, morphology, and procoagulant outputs. In rats, infection with wild type increased RBC remodeling and venous thrombosis, whereas infection with ΔehxA did not. Together, the data define an EhxA-Ca2+-PS pathway that drives RBC structural remodeling and procoagulant activation during EHEC infection and nominate RTX toxins as targets for preventing toxin-induced coagulopathies.

Uncontrollable noncompressible bleeding has always been a major cause of death and disability among civilians and military personnel. Herein, a biodegradable, self-gelling protease-grafted alginate dressing was developed for efficient noncompressible bleeding control. The hemostatic dressing was fabricated through a high-degree sodium ion exchange of calcium alginate fibers, followed by covalent grafting of trypsin via carbodiimide chemistry. This design confers exceptional swelling capacity and rapid gelation within seconds upon blood contact, forming a physical barrier. The grafted trypsin establishes an artificial coagulation pathway independent of endogenous factors, significantly shortening in vitro clotting times. Moreover, it promotes adhesion and aggregation of red blood cells and platelets, accelerating clot formation and increasing the clot strength. In a rabbit liver injury model, the dressing achieved hemostasis within 70 s, significantly reducing blood loss and promoting wound healing compared to commercial SURGICEL while demonstrating excellent biocompatibility and biodegradability. The protease-grafted alginate dressing exhibited high robustness against high-temperature treatment, maintaining its high procoagulant activity in vitro for over 55 days at 47 °C.

To develop and validate a predictive model for distinguishing controls (Ctr), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) based on nailfold videocapillaroscopy (NVC) image features. A total of 600 NVC images from 396 participants (Ctr=117, RA=337 and SLE=146) were collected and divided into training and test sets at a 7:3 ratio. Nine NVC features were extracted, and an eXtreme Gradient Boosting multiclassification model was constructed to distinguish the three groups. SHapley Additive exPlanations (SHAP) analysis was performed to evaluate feature importance and interpret the model. Seven NVC features showed significant differences among the groups. The model achieved macro area under the curve values of 0.96 and 0.80 in the training and test sets, respectively. SHAP analysis identified papilla shape, red blood cell aggregation, number of capillary loops, number of crossed capillary loops and subpapillary venous plexus (SVP) as key features among the groups. Each group was characterised by specific NVC patterns. In Ctr, papilla shape emerged as the key feature and showed correlations with neutrophils, white blood cells and monocytes. In patients with RA, the number of crossed capillary loops was the most prominent feature and correlated with erythrocyte sedimentation rate, complement levels (C3 and C4) and inversely with immunoglobulin G. In patients with SLE, the SVP was the dominant feature and effectively distinguished SLE from both Ctr and RA. This study developed a robust multiclassification model for differentiating autoimmune diseases using NVC features. The findings enhance our understanding of microvascular alterations and provide a potential tool for clinical diagnosis and disease monitoring.

BackgroundThe hemorheological and microcirculatory aspects of the pathophysiology of sepsis are partially understood and are often controversial in terms of the dynamics, extent, and correlation of parameters. We aimed to simultaneously investigate hemorheological and multi-organ microcirculatory changes in abdominal sepsis in the rat. Sixteen male Wistar rats (body weight: 389.1 ± 44.9 g) were included in our studies. Animals were randomly assigned to sham-operated control (n=8) or sepsis group (n=8). In the sepsis group, sepsis induction was performed by coecum ligation and puncture after median laparotomy. In the sham-operated group, only laparotomy and abdominal wall closure were performed. Body and rectal temperature, respiratory rate, abdominal aortic blood flow (T206 Transonic System) were measured before and after 24 h after surgery, and microcirculatory recordings were captured using a Cytocam-IDF camera in several localizations (skin, coecum, kidney). A scoring system has been developed for the evaluation of the recordings. These video images were evaluated semi-quantitatively based on the deviations (oedema, presence of red blood cell aggregates, flow heterogeneity and vasculature regularity, scored with 0–4 points per category). After blood sampling, we determined hematological, hemorheological, acid-base, and metabolic parameters.ResultsBody and rectal temperatures were significantly elevated in the sepsis group compared to the control group (p=0.005; p=0.016). Major increases in lactate and creatinine concentrations indicated progression of sepsis (p<0.001 vs. baseline). Increased deterioration of microcirculation was observed: the percentage and density of perfused vessels were significantly decreased in sepsis (coecum: p<0.001 vs. baseline). We saw similar results during scoring the videos, with heterogeneous blood flow and elevated number of aggregates. Erythrocyte aggregation parameters were increased in the sepsis and control group (p<0.001 vs. baseline) and erythrocyte deformability showed a significant decrease (EImax: p=0.012 vs. baseline).ConclusionThe micro-rheological parameters of erythrocytes and microcirculatory changes can majorly impact tissue perfusion during sepsis. The analysis of microcirculatory recordings and the new scoring system can provide useful information on the impact of sepsis on tissue microcirculation.