Cell senescence may explain why people suddenly become more prone to deep vein thrombosis once they reach the age of 45, new research has shown.

Thrombosis is the formation of a blood clot inside of a blood vessel, which disrupts the flow of blood around the body. Thrombosis incidence is extremely low in people below the age of 45 but rises rapidly as people age and is a major cause of death. It is also a dangerous side effect of chemotherapy. As both ageing and chemotherapy drugs can promote cell senescence, researchers wondered if this process could be the cause of deep vein thrombosis.

Senescent cells are no longer able to divide and proliferate. Chemotherapy induces senescence in cells by causing DNA damage, and senescence can also be caused by the stresses associated with ageing. However, senescent cells are still able to produce regulatory signals, known as SASP factors, that play a role in injury recovery.

Mice were dosed with the chemotherapy drug doxorubicin (DOXO) to induce cell senescence. The SASP factors were compared between the senescent and non-senescent cells. It was found that increased levels of SASP factors in senescent cells correlated with higher levels of mRNAs encoding factors that regulated blood clotting.

It is therefore possible that cell senescence could initiate excessive blood clotting and cause thrombosis, and that this effect could be reduced by blocking the release of SASP factors.