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Stem cells from embryos have been both controversial and filled with the promise of treatments and cures for many diseases and disorders. Embryonic stem cells, unlike adult stem cells, are blank slates that hold the potential of developing into specialized types of cells, such as bone marrow, nerve cells, heart muscle cells and pancreatic islet cells. Since they are a renewable source of numerous kinds of human cells, their ultimate use will play itself out in replacing cells and tissues ravaged by diseases and conditions, and restoring their vital functions too. To date, studies have shown that stem cells could effectively serve such purposes as to create healthy heart muscle cells for hearts weakened by cardiovascular disease, or islet cells in the pancreas to allow Type I diabetics to produce their own insulin and forego injections.

One study (Proc. Natl. Acad. Sci. USA, May 23, 2000) suggests that pluripotent embryonic stem cells can be used to help restore neurological function to patients with spinal damage. Pluripotent stem cells are cells that have the possibility of forming virtually any type of human body cells, but they fall short of being able to form an organism, namely a fetus. Researchers at the Washington University School of Medicine showed that these stem cells could be made to change into nerve cells known as oligodendrocytes, which can help to subsequently yield myelin-producing cells. It is important to replenish diminished levels of myelin, an essential fatty material that enshrouds these nerve cells, which is damaged by various diseases or injury. As the authors explain, demyelination, or the loss of myelin, is what contributes to functional loss in spinal cord injuries.

Using rats to test the stem cells, the study found that embryonic stem cells could survive, migrate and differentiate into myelin-producing cells in areas where there is an evident lack of myelin due to damage. First, the researchers transplanted the cells into the dorsal columns of adult rat spinal cords three days after chemically inducing demyelination. Results showed that these cells survived and developed into mature oligodendrocytes. Moreover, even when the researchers planted the cells into the spines of mutant mice that had been genetically altered to be missing a myelin-producing gene, myelin production occurred as well.

The researchers reported being able to produce myelin from the stem cells within not much more than a week’s time, whereas the process had previously taken about four to six weeks. Transplanting myelin-producing cells in the future may mean the reversal of damage to nerves within the spinal cord, as well as affected muscles. “Enhanced remyelination through transplantation of myelin-producing cells may offer a pragmatic approach to restoring meaningful neurological function,” suggest the authors. Presently, there’s still a ban on the use of federal funds for the research of human embryonic stem cells, but the authors are hopeful that they’ll be able to offer a stem cell-based treatment within the next five years.