Platelets naturally home to solid tumors, which have been described as “wounds that do not heal.” [Harold F. Dvorak, Tumors: Wounds That Do Not Heal. New England Journal of Medicine. 1986] Unlike most every other transplantable cell, platelets do not have a nucleus and are therefore incapable of proliferation and cannot cause cancer. Platelet circulation time in the blood is predictably short (10 days) and tunable, which makes them ideal delivery vehicles for drugs.
Most importantly, unlike red blood cells, platelets possess secretory granules, which can hide a drug payload and then deliver it upon arrival at the site of a tumor.