03 Dec 1999

In the political arena, there is almost daily rhetoric about the use of fetal and embryonic tissue in research. Meanwhile, in the laboratory, researchers continue to produce results certain to keep those issues on the front burner. A significant addition is a study published in the current Nature Neuroscience which demonstrates that mouse embryonic stem cells can restore significant function in rats with spinal cord injury.

John McDonald and colleagues at Washington University in St. Louis implanted mouse neural embryonic stem cells into experimentally produced spinal lesions in rats. Two weeks after the transplant, they found that the cells had spread throughout the area of the lesion, differentiating into oligodendrocytes (43 percent of surviving cells), astrocytes (19 percent) and even some neurons (eight percent). After five weeks, the number of surviving cells had dropped, but they had been replace by extracellular matrix with constituent fibers derived from the transplanted cells. The cell survival was accompanied by significant improvements in the ability of the hind limbs to bear weight and to show some coordination of movement.

One of the things that makes the study particularly interesting for Alzheimer's research is that the stem cells were not transplanted until nine days after the injury. "Behavioral recovery similar in magnitude to that shown here has previously only been shown in acute injury models," write the authors.—Hakon Heimer

[For a particularly succinct, yet thorough, introduction to the political discussion about embryonic and fetal tissue, see an editorial by Annas et al. in the same issue.]