Rheologically determined time-to-gel point (TGP) is sensitive to both mechanical loading and underlying health status, and when complemented by structural and biological analyses, provides a quantitative marker for assessing patient-specific haemostatic function and thrombotic risk.
Key Findings
Results
Time-to-gel point (TGP) decreased with increasing applied shear stress, demonstrating accelerated clot formation under higher mechanical loading.
Platelet-rich plasma (PRP) from 30 volunteers was analysed using oscillatory rheometry at 37°C using an Anton Paar rheometer.
Amplitude sweep experiments established a linear viscoelastic region between 1 and 10 Pa.
Rheological measurements were performed within a conservative stress range of 1–4 Pa.
TGP was determined using the frequency-independent loss tangent criterion based on the Chambon-Winter gelation theory.
Results
Smokers and individuals with type 2 diabetes consistently exhibited shorter TGP, clotting time (CT), and prothrombin time (PT) values compared with healthy controls, indicating enhanced coagulation potential.
The study included 30 volunteers representing three cohorts: healthy, smoker, and type 2 diabetic individuals.
Shorter TGP, CT, and PT were observed across all applied shear stress conditions for smoker and diabetic groups relative to healthy controls.
Conventional clotting time and prothrombin time measurements were used to validate the rheological findings.
A priori power analysis confirmed that the study was adequately powered to detect the observed intergroup differences.
Results
Older participants demonstrated reduced TGP relative to younger healthy individuals, suggesting an age-related increase in procoagulant behaviour.
Age was examined as an additional variable alongside smoking and diabetes status.
Reduced TGP in older participants was observed using the same oscillatory rheometry protocol applied to all cohorts.
This finding was identified within the same sample of 30 volunteers across the study cohorts.
Results
Field-emission scanning electron microscopy (FESEM) revealed denser fibrin networks with reduced pore size at higher shear stresses.
FESEM was used to examine clot microstructure across different shear stress conditions.
Denser fibrin networks and reduced pore size were observed as applied shear stress increased.
These structural changes are consistent with the accelerated clot formation indicated by shorter TGP values at higher shear stresses.
CD62P (P-selectin) is a marker of platelet activation expressed on the platelet surface upon activation.
Fluorescence microscopy was used alongside FESEM to examine platelet activation and clot microstructure.
Increased CD62P expression at higher shear stresses confirmed that mechanical loading progressively activates platelets.
These biological findings complemented the rheological and structural data.
Methods
The linear viscoelastic region for platelet-rich plasma was established between 1 and 10 Pa using amplitude sweep experiments.
Amplitude sweep experiments were conducted prior to time-sweep measurements to define the linear viscoelastic region.
The established linear viscoelastic region of 1–10 Pa informed the conservative stress range of 1–4 Pa used for subsequent rheological measurements.
PRP samples were maintained at 37°C throughout testing to reflect physiological conditions.
What This Means
This research suggests that the mechanical forces blood experiences as it flows through vessels can directly influence how quickly it clots. By testing platelet-rich plasma from 30 people — some healthy, some smokers, and some with type 2 diabetes — using a specialized instrument that measures gel-like properties, the researchers found that higher shear stress (a force similar to what blood experiences in narrowed or turbulent vessels) caused blood to clot faster across all groups. Smokers and diabetics clotted faster than healthy individuals under the same conditions, and older people also showed a tendency toward faster clotting than younger healthy participants.
The study also used electron microscopy to look at the physical structure of clots and found that higher shear stress produced denser fibrin networks with smaller pores — characteristics associated with clots that are harder to break down. Additionally, a biological marker of platelet activation (CD62P) increased with higher shear stress, confirming that mechanical forces were directly triggering platelets to become more active and contribute to clotting. These findings held true across all participant groups, with smokers and diabetics showing the most pronounced responses.
This research suggests that a rheological measurement called the 'time-to-gel point' could serve as a useful, patient-specific tool for quantifying clotting risk, particularly when combined with structural and biological analyses. The results indicate that people who smoke or have type 2 diabetes may face compounded thrombotic risk when their blood is also exposed to elevated mechanical forces, such as those occurring in diseased or narrowed blood vessels. This approach could offer a more nuanced picture of individual clotting behaviour than conventional clotting time tests alone.
Taharat S, Aumiyo S, Roshni A, Islam N. (2026). Shear stress and blood coagulation: A comparative study of smokers and diabetics, with healthy individuals.. Microvascular research. https://doi.org/10.1016/j.mvr.2026.105007