Implantation of neural stem cells yielded elevated BDNF and increased synaptic density in a mouse model of Alzheimer's disease [22] while mouse models of ischemia reveal that administration of embryonic stem cells (ESCs) can lead to the restoration of behavioral deficits, synaptic connections, and damaged neurons through the release of neurotrophic factors such as BDNF, NGF, and GDNF [23–25]. The gene discussed is BDNF; the disease is Alzheimer disease.