You may have seen the famous performer David Copperfield appear to change a car into an elephant. Recently, neuroscientists appeared no less magical when they transformed blood cells into brain cells. Two research groups reported in the December 1 issue of Science that bone marrow cells can travel to the brain and turn into nerve cells. Bone marrow, the soft material inside your bones, is composed of at least two types of stem cells . Stem cells are not yet mature and have the ability to become specialized cells.
Different signals tell the stem cell what type of cell to become.
This process is called differentiation , because the cells are migrating to where they belong and becoming different cell types. Scientists used to believe that once a stem cell became a specialized cell, say a liver cell, that its cell type was unchangeable. Recent work, however, is breaking down this long-held belief. In order to trace what happens to the transplanted cells, scientist need a marker, something that identifies the transplanted cells from the cells that were already there. For example, if you put red ants into an antpile that housed black ants, it would be easy to see where your red ants went.