TSI is a privately-held vascular medicine and biotechnology company currently developing a new-generation clot-dissolving therapy with the first novel mechanism of action in 20 years for stroke and other thrombotic diseases. TSI’s technology is based upon pioneering earlier work on pro-urokinase (proUK) by its cofounders. The primary component of TSI’s thrombolytic therapy is a rationally designed mutant of proUK.