Rapid restoration of blood flow to ischemic brain is essential to prevent irreversible tissue injury and minimize neuronal function impairment after acute ischemic stroke. However, intracerebral hemorrhage, reperfusion injury and the oxidative stress provoked by returned blood supply remain the major concerns for the use of effective thrombolytic agent; such as, recombinant tissue plasminogen activator (rt-PA). DC009 is a novel small molecule designed to have both thrombolytic and free radical scavenging activities, which were characterized in various in vitro and in vivo models.
The thrombolytic effect of DC009 was demonstrated in vitro using whole blood clot lysis assay and euglobulin clot lysis assay. In comparison to rt-PA (1mg/ml), DC009 (11.11 mg/ml) exerts comparable (p value = 0.40) in vitro thrombolytic activity to rt-PA. Further investigation showed that DC009 induced endogenous t-PA protein secretion from endothelial vesicles, and it enhanced endothelial t-PA mRNA expression through cAMP pathway. Ability of DC009 in ABTS radical cation scavenging (2, 2-azinobis-(3-ethylbenzthiazoline-6-sulfonate) was measured and found to be dose dependent with an EC50 of 49 μM.
Using a focal cerebral ischemia induced by arterial thrombosis model in aged mice (12-15 months old), DC009 showed a steady thrombolytic action and superior safety profile compared to vessel recanalization induced by rt-PA.
We further investigated DC009’s effect on normal hemostasis and maximal tolerable dose (MTD) level in rodents in order to assess its therapeutic potential. At their comparable pharmacological dose, the tail amputation bleeding assay in mice showed that DC009 (up to 30mg/kg) did not cause bleeding prolongation; vs. rt-PA (10mg/kg) prolonged the bleeding to >10 folds of normal bleeding time. According to the MTD determined in preliminary toxicity dose range finding studies, greater 50 folds of safety margin was identified in both mouse and rat.
In conclusion, DC009 appears to both thrombolytic and free radical scavenging with minimal risk of bleeding. As a safe and dual functional small molecule, it is a drug candidate of great potential for the treatment of ischemic stroke.