Science Friday Reagan Edition: Stem Cells and Alzheimer's

A pair of recently announced breakthroughs have yielded some surprising and hopeful results in both the fight to solve the mystery of Alzheimer's Disease, and in our overall understanding of the brain.

Three years ago, researchers at Duke University Medical Center succeeded in "re-training" adult fat cells into cartilage cells, and, eventually, bone cells, something which had previously only been possible using stem cells. Of course, fat, cartilage, and bone have significant similarities, being mesenchymal, or connective tissue. A year later, however, a different team of Duke University Medical Center researchers managed to turn fat cells into something resembling nerve cells, which are not mesenchymal.

According to Science Daily, the latest issue of Experimental Neurology carries a follow-up from those researchers, Kristen Safford and Henry Rice (he's the one with the beard), which demonstrates that their laboratory-created cells appear to actually behave as nerve cells. The ability to create nerve cells in the lab using leftover liposuction junk, as opposed to embryonic stem cells, could have obvious implications in the fight against Alzheimer's Disease.

The researchers exposed these cells to N-methyl-D-aspartate (NMDA), a chemical which kills nerve cells by blocking the activity of glutamate, a common neurotransmitter (it is thought that much of the damage caused by a stroke is due to over-stimulation of NMDA receptors on nerve cells). The cells displayed a toxic response to the NMDA which was similar to that of neural tissue.

Their next step, obviously, is to implant the newly-created cells into a living animal, and see if they do, in fact, function as nerve tissue. If they do, in fact, work, their initial use would undoubtedly be in stroke or paralysis victims — think Christopher Reeve rather than Ronald Reagan — however, this and other ongoing research on "re-differentiating" existing cells into nerve tissue could have implications for an enormous range of different medical conditions, including, obviously, Alzheimer's.



Speaking of Alzheimer's, Science Daily is also reporting on surprising new research on Alzheimer's Disease done by scientists at the Howard Hughes Medical Institute at Washington University in St. Louis (yay, wustl!).

In the June 10 issue of the succintly-named journal Neuron, researchers Randy L. Buckner and Cindy Lustig described a study of the functions of implicit memory, the type of memory that allows people to do things like perform tasks which they have learned to do, even if they do not specifically remember the experience of learning the task (for instance, you can ride a bicycle without remembering the experience of learning to ride a bicycle).

The researchers took a group of young adults, a group of healthy older adults, and a group of older adults who were in the early stages of Alzheimer's Disease, and presented them with lists of words. The subjects were asked to identify the words as representing living or non-living objects. All groups of subjects showed significant response-time improvements after practice, which is considered to be indicative of the effects of implicit learning.

The subjects then repeated the tests while their brains were scanned with an MRI machine. Much to the surprise of the researchers, they discovered that the increased activity in the brain was associated with the high-level region of the frontal cortex, a region of the brain which is thought to be severely damaged by Alzheimer's Disease. Certainly, high-level cognitive abilities of the sort that are disrupted by Alzheimer's are centered in those same regions of the brain.

Furthermore, researchers found that, as test times improved, activity in the frontal cortex was reduced — a finding which suggests that those regions of the brain were becoming more efficient in performing their given task. This effect, when combined with the surprising discovery that those regions of the brain are still capable of high-level memory functions in Alzheimer's patients, suggests some interesting new possibilities for therapeutic cognitive training for the elderly — both those afflicted with Alzheimer's and those who are not.

At the moment, researchers suggest that highly structured training regimens — as opposed to more free-form, spontaneous types of learning — might hold the greatest hope of assistance to older adults. In the meantime, now that they have discovered these high-functioning areas of the brain, they hope that researchers will be able to use their knowledge to further examine the function of implicit memory, and how it might be compromised (or not) in elderly patients.