Biology subjects

Fuhg, J.

Publications and source records attributed to Fuhg, J..

3 recordsLinked to original sources

bioRxiv2026

Flow alters fibrin molecular and network structure and decreases binding of fibrinolytic enzymes

Thrombolysis with tissue Plasminogen Activator (tPA), approved for treating acute ischemic stroke (AIS) within 3-4.5 h of symptom onset, converts Plasminogen (Plg) to Plasmin to degrade fibrin, while fibrin also enhances Plg activation by binding to both tPA and Plg. Therefore, in this study, we investigated whether arterial-like flow, characteristic of AIS, alters fibrin structure and susceptibility to fibrinolysis. Using a newly developed platform for quantitative imaging and spectroscopy, we found that flow generates denser fibrin networks with reduced molecular transport despite reduced protofibril packing within fibrin fibers. Raman spectroscopy revealed an -helix-to-{beta}-sheet transition, accompanied by reduced Plg and tPA binding, although the reduction in tPA binding emerged only after prolonged flow exposure. Consistently, multi-scale molecular dynamics simulations showed that the Plg binding site destabilized at lower forces than the primary tPA binding site. Together, these multi-scale findings help explain the limited efficacy and narrow therapeutic window of thrombolysis.

biophysics↗

bioRxiv2026

MRI-Based Blood Clot Phenotyping: An In Vitro Study

Background and PurposeNeurointerventional outcomes depend on clot composition and may be influenced by clot contraction. Thus, a priori identification of clot composition and contraction could inform procedural strategies and improve outcomes. The goal of our work is to conduct an in vitro test to determine whether MRI can reliably predict both clot composition and contractile state. Materials and MethodsTo this end, we prepared blood clots spanning clinically observed compositions (0-80% red blood cells (RBCs)) in both contracted and uncontracted states. Contraction was controlled by coagulating blood with or without thrombin. We imaged these clots using quantitative, clinical, and investigational MRI sequences. Using these data, we then determined whether MRI signal intensities, quantitative parameters, and radiomic features capturing intensity and texture patterns can (i) predict clot hematocrit and (ii) classify clots by composition (RBC-rich vs. fibrin-rich) and contraction state. ResultsQuantitative MRI parameters (T1, T2, ADC) decreased with increasing hematocrit (R2 = 0.56-0.85, p < 0.001), while signal intensities from clinical sequences showed weaker correlations (R2 = 0.46-0.62, p < 0.001). Radiomic models predicted hematocrit with performance comparable to MRI parameters. When applied to classification, radiomic features accurately discriminated RBC-versus fibrin-rich clots, with AUCs exceeding 0.90 across nearly all sequences. In contrast, classification of contraction state showed greater variability in AUCs across sequences but remained high for quantitative T1 and T2 values (AUCs up to 0.88). Trends were consistent across clots coagulated with and without thrombin. Pooling features across sequences did not outperform the best individual sequence for either regression or classification. ConclusionsWe demonstrate that MRI-based radiomic analysis quantitatively characterizes clot composition and contraction in vitro. These findings support the feasibility of using MRI for pre-interventional clot phenotyping, with potential to inform thrombolytic and mechanical thrombectomy strategies. Thus, in vivo studies validating these results are warranted.

bioengineering↗

bioRxiv2025

In vitro blood clot mechanical properties depend on fibrinogen and white blood cell subtypes in addition to hematocrit

BackgroundUnderstanding the role of blood composition in clot mechanics may provide critical cues toward their diagnosis and treatment. To this end, we previously showed that sex and standard blood composition measures explain some variability in clot mechanics, but much remains unaccounted for. Ours and others studies ignored the roles of fibrinogen and white blood cell (WBC) subtypes, which is surprising given their physiological importance. ObjectiveTo develop a more complete understanding of what determines clots mechanical properties, we now study the role of previously untested factors, namely fibrinogen levels and WBC subtypes, in addition to sex and standard blood composition measures. MethodsWe drew blood from healthy young adults and prepared in vitro clot samples. Using pure shear and mode-I fracture tests, we measured clots stiffness, fracture toughness, strength, and work to rupture. We then used linear regressions to quantify how blood composition influences clot mechanical properties, reporting R2 to assess explanatory power. ResultsWe found that fibrinogen is the strongest predictor of clot mechanical properties, positively correlating with all four metrics and achieving the highest average R2. For example, fibrinogen accounts for 70% of the variation in stiffness and 78% in fracture toughness. Among WBC subtypes, neutrophils positively correlate with strength and work to rupture, whereas eosinophils negatively correlate with strength. ConclusionOur work shows that fibrinogen levels and WBC subtypes are previously untested but major determinants of in vitro clot mechanical properties. Future studies should connect these findings to in vivo clot behavior and clinical outcomes.

bioengineering↗