The neuroprotective effects of xenon and helium in an in vitro model of traumatic brain injury

Objectives: The "inert" gas xenon has been shown to be an effective neuroprotectant in a variety of in vitro and in vivo models of neuronal injury. We examined its neuroprotective properties in an in vitro model of traumatic brain injury. Design. Controlled laboratory study. Setting: Academic research laboratory. Subjects. Organotypic hippocampal brain slices from mice pups. Interventions. The cultured brain slices were subjected to a focal mechanical trauma, and injury was monitored in the presence and absence of inert gases at normal and elevated pressures and under both normothermic and hypothermic conditions. Measurements and Main Results: Neuronal injury was quantified using propidium iodide, which becomes fluorescent only when it enters injured cells. Low pressures of both helium and xenon were effective neuroprotectants when applied in addition to 1 atm of air. Moreover, both gases were effective at normal pressures when they replaced nitrogen in a gas mixture. Conclusions. The inert gases helium and xenon are effective neuroprotectants in a model for traumatic brain injury, and this novel treatment warrants further investigation. Xenon was particularly effective at reducing the secondary injury that developed following the initial trauma and could be administered at least 3 hrs postinjury with only a small reduction in efficacy.