Tracking inflammation in the epileptic rat brain by bi-functional fluorescent and magnetic nanoparticles

Correct localization of epileptic foci can improve surgical outcome in patients with drug-resistant seizures. Our aim was to demonstrate that systemically injected nanoparticles identify activated immune cells, which have been reported to accumulate in epileptogenic brain tissue. Fluorescent and magnetite-labeled nanoparticles were injected intravenously to rats with lithium-pilocarpine-induced chronic epilepsy. Cerebral uptake was studied ex vivo by confocal microscopy and MRI. Cellular uptake and biological effects were characterized in vitro in murine monocytes and microglia cell lines. Microscopy confirmed that the nanoparticles selectively accumulate within myeloid cells in the hippocampus, in association with inflammation. The nanoparticle signal was also detectable by MRI. The in vitro studies demonstrate rapid nanoparticle uptake and good cellular tolerability. We show that nanoparticles can target myeloid cells in epileptogenic brain tissue. This system can contribute to pre-surgical and intra-surgical localization of epileptic foci, and assist in detecting immune system involvement in epilepsy.