Changes in the level of thrombomodulin with aging

Thrombomodulin (TM) is a thrombin receptor on endothelial cells. When endothelial cells are damaged TM is degraded and released into the blood. We examined whether levels of TM in plasma reflect endothelial damage related to aging. We measured the TM level in samples of plasma from 93 healthy men aged from 22 to 81 years. None had hypertension, obesity, diabetes mellitus, or cardiovascular disease. The relationship between the level of TM (Y) and age (X) could be approximated by Y=0.176X + 10.3379, the correlation was significant (r=0.647, p<0.01). Basal levels of TM in subjects from 20 to 60 years old showed a gradual increase, that was not statistically significant. Basal concentrations of TM were significantly higher in the older subjects than in the younger subjects. The high levels of TM in the older subjects might reflect endothelial damage. In conclusion, a high TM level in plasma may be a sign of endothelial damage related to aging.