Stem Cells and Alzheimer's

The prospect of curing Alzheimer's with the use of stem cells is both exciting and daunting. It would be immensely difficult because a large variety of neurons are affected in the brain of an Alzheimer's patient. Therefore, in order to have a positive effect, neural stem cells would have to be able to travel throughout the brain to places that have been damaged and produce many different types of neurons that are able to integrate into the brain and make connections that were once made by the damaged cells. 

So far, tests conducted in mice have had small success, and scientists worry that the brains of Alzheimer's patients would lack the ability to reform important neural connections with the stem cells. Also, stem cells placed in the brain might be damaged by amyloid and tau proteins, proteins that aggregate in the brain due to Alzheimers disease. Stem cells could have potential benefits for Alzheimers patients through their production of neurotrophins. Neurotrophins are proteins that support the development of neurons in a healthy brain, but are scarce in Alzheimer’s patients. Experiments in mice have shown some memory improvement thanks to the neurotrophins produced by neural stem cells.

Scientists have been able to create induced pluripotent stem (iPS) cells that mimic the neurons found in the brains of Alzheimer's patients. The iPS cells release the amyloid beta protein, a main factor in Alzheimer's and a primary component in plaques within the brain. This is highly useful in that it gives scientists the ability to study the disease and how it varies from one individual from the next.

Sources: 

http://www.eurostemcell.org/factsheet/alzheimers-disease-how-could-stem-cells-help