Evaluation of platelet hyperfunction in aged subjects using spontaneous platelet aggregation in whole blood

Platelets in aging and cancer-"double-edged sword"

Platelets control hemostasis and play a key role in inflammation and immunity. However, platelet function may change during aging, and a role for these versatile cells in many age-related pathological processes is emerging. In addition to a well-known role in cardiovascular disease, platelet activity is now thought to contribute to cancer cell metastasis and tumor-associated venous thromboembolism (VTE) development. Worldwide, the great majority of all patients with cardiovascular disease and some with cancer receive anti-platelet therapy to reduce the risk of thrombosis. However, not only do thrombotic diseases remain a leading cause of morbidity and mortality, cancer, especially metastasis, is still the second cause of death worldwide. Understanding how platelets change during aging and how they may contribute to aging-related diseases such as cancer may contribute to steps taken along the road towards a "healthy aging" strategy. Here, we review the changes that occur in platelets during aging, and investigate how these versatile blood components contribute to cancer progression.

Age related elevation of serum macrophage colony stimulating factor (M-CSF) level

We recently reported that the serum level of macrophage colony-stimulating factor (M-CSF) was elevated in patients with cerebral infarction. In the present study, we measured serum M-CSF level, as well as coagulo-fibrinolytic markers and general laboratory tests in adult healthy subjects of various ages, and investigated the relationship between age and M-CSF level. M-CSF in aged subjects (>or=65 years of age) was significantly higher than that in the younger subjects (<65 years of age), and a significant positive correlation between age and M-CSF was found. Significant positive correlations between M-CSF, and plasma levels of thrombomodulin (TM), von Willebrand factor antigen (vWF), thrombin-antithrombin III complex (TAT), prothrombin fragment 1+2 (F1+2), d-dimer products cross-linked fibrin degradation products (d-dimer) and plasmin-antiplasmin complex (PAP) were also found. Among the general laboratory tests, there was only a significant correlation between M-CSF and serum creatinine; however, no significant correlation was found between M-CSF and other tests including blood cell counts. From these results, age-related elevation of serum M-CSF level was confirmed, and was suggested not to indicate the alteration of hemopoietic condition in aged subjects but to be related to thrombotic state or systemic damaged blood vessel in the apparently healthy aged people.

Age-related augmentation of stroke tendency evaluated using plasma P-selectin levels

Plasma soluble P-selectin is thought to be a useful marker for thrombotic diseases. To evaluate the thrombotic state and risk of stroke in aged healthy subjects, we investigated plasma P-selectin levels in healthy subjects and ischemic stroke patients. Plasma P-selectin was measured in 67 healthy subjects and 35 aged (>or= 65 years of age) patients with chronic ischemic stroke using a sandwich enzyme-linked immunosorbent assay (ELISA). Plasma P-selectin was significantly higher in aged (>or= 65 years of age) healthy subjects than in young (< 65 years of age) healthy subjects. Significant difference did not exist between aged healthy subjects and aged stroke patients who were not receiving anti-platelet agents. Anti-platelet agent had no significant effect on plasma P-selectin levels in aged stroke patients. The amounts of P-selectin released from platelets into the plasma after stimulation with adenosin diphosphate in young and aged healthy subjects were not significantly different. Elevated levels of P-selectin in aged healthy subjects suggests the existence of a subclinical thrombotic state which can result in a stroke. Elevated P-selectin levels are not thought to be due to platelet hyperfunction.