NGF and Alzheimer disease: As such a promising neurotrophic factor, NGF had been clinically tried to apply into other neuropathies, Alzheimer's disease (AD) therapy [27] and neuropathic pain control [28], by injecting the combined AAV-NGF vector and using targeted anti-NGF-antibodies, but vector mistargeting and blood-brain barrier defense were observed as the defects by clinical trials [29].