Nanosphere-mediated delivery of vitamin E increases its efficacy against oxidative stress resulting from exposure to amyloid beta.

Oxidative stress is an early hallmark of affected neurons in Alzheimer's disease (AD). The antioxidant vitamin E provided limited neuroprotection in AD, which may have derived from its lipophilic nature and resultant inability to quench cytosolic reactive oxygen species (ROS), including those generated from antecedent membrane oxidative damage. We examined herein whether or not encapsulation into polyethylene glycol (PEG)-based nanospheres, which can enter the cytosol, improved the efficacy of vitamin E against amyloid-beta(Abeta)-induced ROS. Unexcapsulated vitamin E prevented Abeta-induced ROS in cultured SH-SY-5Y human neuroblastoma cells only if present prior to, or applied simultaneously with, Abeta treatment. By contrast, encapsulated vitamin E was equally effective if administered 1 hr after Abeta exposure. These findings suggest suggests that nanosphere-mediated delivery methods may be a useful adjunct for antioxidant therapy in AD.