Bone Marrow Can Grow New Brain Cells

ActMatrix writes: "Scientists at Stanford and the National Institute of Neurological Disorders and Stroke have demonstrated that stem cells in bone marrow can produce neurons that replace dead brain cells, similar to the way our bodies constantly replenish skin cells. What isn't certain yet is whether these new brain cells make functional neural connections. If they do, it's possible that doctors will some day use marrow transplants to treat brain disorders. What's especially cool is how they discovered this. In one case, mice whose natural bone marrow was killed by radiation were injected in the tail with marrow containing a phosphorescent protein. When the mice were killed later, parts of their brains glowed in the dark. =) Article with some more details from CNN here."

Comments

Glow in the dark brain != Neural Regeneration

[dondelelcaro]

Science in CNN is always interesting. Time to go to the primary source to figure out what is actually going on.

To examine whether bone marrow-derived cells could give rise to cells in the brain, adult marrow was harvested from transgenic mice (8 to 10 weeks of age) that ubiquitously expressed enhanced green fluorescent protein (GFP) (13). GFP-expressing (GFP+) bone marrow was administered by tail vein injection (6 × 106 nucleated cells per recipient) into lethally irradiated, isogenic adult (8- to 10-week-old) recipients (14). Brains harvested several months after the transplant (post-transplant) and examined by light microscopy revealed the presence of GFP+ cells throughout the CNS, including the olfactory bulb, hippocampus, cortical areas, and cerebellum. No cells expressed detectable GFP in five age-matched bone marrow recipients (controls) transplanted with marrow that was not genetically engineered to express GFP. Thus, bone marrow-derived GFP+ cells were clearly present in the brain.

Unfortuanatly, the mere precense of green florescing protein doesn't conclusively demonstrate that the bone-marrow cells have become neurons. I submit that if you were to look at cells throughout the body, you would have found differentiated stem cells glowing throughout the entire mouse. Nicely however, this data isn't shown, or even elluded to.

However, what does begin to demonstrate that the bone-marrow cells actually became neuronal cells is the staining process, where you stain for neuronal proteins. Of course, B cells have a nasty habit of trapping free neuronal proteins, so you would have to control for that, but that can be overcome. Course, one would really like to see a protein affinity study to conclusively demonstrate that the cells are actually neuronal, but I'm not a neurologist, so I won't digress.

Merzey's work deals more elegantly with the problem by not dealing with GPF at all and instead heading straight for genetic material, by using male stem cells in a female mice. (XY instead of XX, trivial to find Y using staining microscopy) This cleans up most of the nastyness of the GPF.

In addition Merzy deals with the differentiation of neuronal cells much more effectively, convicing me at least that these stem cells actually became neuronal cells, rather than just leaking out into the brain accidental like. Of course, the real trick now is to figure out what got the cells to become neurons.

I'm going to guess that it only works in stem cells, and occurs because of the influence of neuronal proteins on neurons affects the differentiation of cells that can actually change fate into something that suits their environment. (Ie, have a non-locked (non-genetic) path determination). Probably just the proteins that turned the neurons into neurons in the first place continue to act on cells that through some strange occurence end up in the range of those proteins

Oh yeah... for those of you who are actually interested, here is the links to the articles. Turning Blood into Brain: Cells Bearing Neuronal Antigens Generated in Vivo from Bone Marrow and From Marrow to Brain: Expression of Neuronal Phenotypes in Adult Mice.
Science 290:1779 and Science 290:1775 respectively.

Don Armstrong -".naidnE elttiL etah I"