A recent investigation sheds light on how blood clotting works in individuals with haemophilia A, which is the most prevalent type of haemophilia. The research team discovered that saliva contains unique vesicles that can quickly accelerate blood clotting for patients with this condition.
A recent study directed by MedUni Vienna offers fresh perspectives on how coagulation functions in people with haemophilia A, which is the most common form of this disorder. The researchers found that saliva includes specialized vesicles that promote swift blood coagulation in haemophilic patients. These findings, published in the scientific journal Blood, greatly enhance our understanding of this condition.
Haemophilia is an inherited blood disorder marked by a shortage of certain coagulation factors, possibly leading to severe bleeding if untreated. The reasons why haemophilia A (characterized by a deficiency in factor VIII) frequently results in bleeding in joints, but rarely in mucous membranes, were not previously understood. To find answers, the research group headed by Johannes Thaler and Cihan Ay (from the Clinical Division of Hematology and Hemostaseology at the Department of Medicine I, MedUni Vienna) along with Rienk Nieuwland (from Amsterdam University Medical Centers) delved into past research concerning the role of the body’s own fluids in blood clotting, a topic that had been overlooked for years.
In their study, the researchers found that the saliva of patients with haemophilia A contains extrinsic tenase complexes situated on vesicles. These complexes consist of two coagulation factors (tissue factor TF and factor VIIa) and kick-start the coagulation cascade upon contact with blood. Their analyses revealed that mucosal bleeding within the mouths of these patients is infrequent and usually resolves quickly. In contrast, patients lacking this protein complex in their saliva often experience oral mucosal bleeding. “This is why they frequently suffer from bleeding in the mouth,” explains Johannes Thaler.
Body fluids as initiators of blood clotting
The role of bodily fluids in the clotting process was first noted in the 1930s when the average lifespan of individuals with haemophilia was merely eight years. The Viennese pediatrician Alphons Solé discovered that breast milk serves as a potent catalyst for coagulation. He demonstrated through clinical trials that tampons soaked in maternal milk could swiftly halt acute, previously unstoppable bleeding in haemophilia patients. Despite verification of Solé’s discoveries by others, this knowledge faded into obscurity. Only recently have Johannes Thaler, Cihan Ay, and Rienk Nieuwland revived this historical investigation, establishing that the blood-coagulating qualities of maternal milk, amniotic fluid, urine—and now saliva—are due to the presence of extracellular vesicles containing extrinsic tenase complexes.
The results offer critical insights into the underlying processes of coagulation and enhance our understanding of haemophilia A. “These findings underline the value of reassessing historical scientific work to create innovative research strategies and potentially improve patient treatment,” reflects Johannes Thaler on the significance of their discoveries.
