Occurrence of epilepsy is controlled in mice by inhibitory neuron transplantation User mubukugrappa, in the Reddit Science subreddit, 06 May 2013
Incredible -> 'brain cells -GABA progenitors- implanted in adult epileptic mice hippocampus, control seizures and abnormal behavior' (in simpler terms than actual title...) User RightTrash, in the Health subreddit, 05 May 2013
Not specific to Narcolepsy with Cataplexy nor humans, but regardless... 'Researchers cure epilepsy in mice using brain cells' User RightTrash, in the Narcolepsy subreddit, 05 May 2013