Safety and efficacy evaluation of carnosine, an endogenous neuroprotective agent for ischemic stroke.

An urgent need exists to develop therapies for stroke that have high efficacy, long therapeutic time windows, and acceptable toxicity. We undertook preclinical investigations of a novel therapeutic approach involving supplementation with carnosine, an endogenous pleiotropic dipeptide. Efficacy and safety of carnosine treatment was evaluated in rat models of permanent or transient middle cerebral artery occlusion. Mechanistic studies used primary neuronal/astrocytic cultures and ex vivo brain homogenates. Intravenous treatment with carnosine exhibited robust cerebroprotection in a dose-dependent manner, with long clinically relevant therapeutic time windows of 6 hours and 9 hours in transient and permanent models, respectively. Histological outcomes and functional improvements including motor and sensory deficits were sustained on 14th day poststroke onset. In safety and tolerability assessments, carnosine did not exhibit any evidence of adverse effects or toxicity. Moreover, histological evaluation of organs, complete blood count, coagulation tests, and the serum chemistry did not reveal any abnormalities. In primary neuronal cell cultures and ex vivo brain homogenates, carnosine exhibited robust antiexcitotoxic, antioxidant, and mitochondria protecting activity. In both permanent and transient ischemic models, carnosine treatment exhibited significant cerebroprotection against histological and functional damage, with wide therapeutic and clinically relevant time windows. Carnosine was well tolerated and exhibited no toxicity. Mechanistic data show that it influences multiple deleterious processes. Taken together, our data suggest that this endogenous pleiotropic dipeptide is a strong candidate for further development as a stroke treatment.