How, specifically, is stem cell therapy used to treat Alzheimer's Disease?

I had to do some research on this one, and from although
scientists have recently conducted successful lab tests in mice that show stem cells can
slow the progression of the disease, there is no scientifically proven procedure or
protocol that is currently successful in treating any of the 18 million people worldwide
who suffer from Alzheimer's.

What the early research in
these lab tests showed is that memory loss was significantly slowed when embryonic stem
cells were injected into the memory portions of the brain in mice affected by the
disease.  The tests have shown enough promise that large investments by medical research
firms and governments around the world have been made into seeing if the success of
these tests can be replicated in humans.

While scientists
are optimistic that a treatment is on the horizon, as of yet, that is not the
case.