Assessment of platelet function in horses: ultrastructure, flow cytometry, and perfusion techniques.
Authors: Segura Dídac, Monreal Luis, Pérez-Pujol Sílvia, Pino Marcos, Ordinas Antonio, Brugués Rosa, White James G, Escolar Ginés
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Assessment of Platelet Function in Horses Researchers employed electron microscopy, flow cytometry, and perfusion assays to characterise the ultrastructure and functional activation of equine platelets, aiming to establish whether haemostatic assessment techniques validated in humans could be reliably applied to equine patients. Resting and activated platelets were examined ultrastructurally, whilst flow cytometry quantified antibody binding to key glycoproteins (GPIIb-IIIa, GPIV, GPIb) and activation markers (P-selectin and lysosomal integral membrane protein), with perfusion studies assessing platelet–subendothelial interactions using citrated and heparin-anticoagulated blood samples. Key findings included a twofold increase in GPIIb-IIIa and GPIV expression post-activation, whilst P-selectin and LIMP expression rose substantially from baseline values of 2.12% and 1.74% to 15.5%–21.86% and 10.50%–11.6% respectively depending on agonist type (thrombin versus collagen); notably, equine platelets demonstrated stronger adhesive responses to damaged subendothelium than human counterparts. Low molecular weight heparin significantly impaired platelet function in vitro, and ultrastructural analysis revealed that horses lack the developed open canalicular system present in humans, instead relying on granule membrane fusion for secretion. These findings have important implications for anticoagulant selection in clinical and surgical settings, whilst validating the use of flow cytometric and perfusion-based platelet assessment techniques for equine haemostatic evaluation in diagnostic and research contexts.
Read the full abstract on PubMed
Practical Takeaways
- •Multiple assessment techniques (ultrastructure, flow cytometry, perfusion) can now be applied to evaluate platelet function in horses, providing more detailed hemostatic evaluation when coagulation disorders are suspected.
- •Anticoagulant choice matters: low molecular weight heparin significantly impairs platelet function in equine blood samples, so alternative anticoagulants should be considered for hemostasis testing.
- •Equine platelets function differently from human platelets in some key ways, so reference ranges and interpretation criteria used in human medicine cannot be directly applied to equine patients.
Key Findings
- •Equine platelets lack a developed open canalicular system and release granule contents through fusion of adjacent granule membranes.
- •Flow cytometry showed 2-fold increase in GPIIb-IIIa and GPIV antibody binding after platelet activation in horses.
- •P-selectin and LIMP binding increased to 15.5% and 11.6% respectively with thrombin activation, and 21.86% and 10.50% with collagen activation.
- •Equine platelets demonstrated stronger reactivity to subendothelium than human platelets, but low molecular weight heparin significantly impaired platelet interactions.