Age-related changes in fibrin networks and platelets of individuals over 75 : a scanning electron microscopy study showing ‘‘thrombotic preparedness’’

Abstract

During aging, changes in vasculature, haemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur. Research has also reported that healthy, aged individuals have heightened coagulation enzyme activity, accompanied by signs of enhanced formation of fibrin and secondary hyperfibrinolysis. It is now believed that the impaired fibrinolytic potential in old age results in a condition that has previously been described as a systemic state of ‘‘thrombotic preparedness’’. This state is far out of proportion to the physiological needs of the person. In the current research we investigate whether this apparent changed thrombotic profile in healthy aged individuals (over the age of 75), is evident in their platelet and fibrin network ultrastructure, when compared to healthy individuals under 25 years. The main differences among young and older individuals were found in the fibrin network ultrastructure. It is concluded that with age, major fibers seem to become thinner and more sparsely arranged and that minor, thin fibers dominate it the coagulum, forming a fine netlike structure. At irregular intervals in the coagulum, thicker, fibrin fiber lattices are present; this is not found in healthy individuals. This might be due to the previously suggested enhanced fibrin formation and heightened coagulation enzyme activity. Here we therefore provide ultrastructural evidence for the thrombotic preparedness previously suggested after studying biochemistry of fibrinolysis and coagulation factors in the elderly.