Embryonic stem cell research has a unique Jekyll and Hyde quality surrounding it. On one hand, it promises the only hope of a cure for people suffering from neurological diseases or spinal cord damage. On the other, it is anathema to many on religious, ethical and moral grounds.

The reason is simple. ES cell research derives from the cells required mainly from embryos or fetuses in a early stage of development. Thus ES cell researchers, normally used to working in obscurity, have found themselves a new focus of the abortion controversy. An article by Antonio Regaldo in a 1998 issue of Technology Review said that workers in that field of research have been subjected to the same threats and intimidation experienced by abortion providers. Now those researchers have won federal approval on a limited scale, and this move is sure to exacerbate the controversy.

In July 1999, a presidential panel agreed that federal funds could be used to support ES cell research under guidelines to be drawn up by the National Institute of Health. The preliminary rules were published four months later and, according to Gretchen Vogel in the Dec. 10 issue of Science, they allow researchers to buy ES strains from private companies if they have been grown according to strict guidelines. These require that the cells come from surplus embryos frozen in fertility clinics and that the donors agree to this use under the stipulation they cannot receive any financial compensation.

The rules for deriving ES cells from aborted fetuses require only that those standards already in place for other fetal tissue research be followed. Final federal approval was given in late August and, in the Sept. 1 issue of Science, Vogel quotes President Clinton as saying, “stem cell research will have potentially staggering benefits.”

Does the approval mean that medical breakthroughs are just over the horizon?

ES cells are found in the earliest stages of embryonic or fetal development in an undifferentiated or pluripotent state. This means that they have the theoretical ability to develop into any tissue in the body.

Reports of ES cells forming new blood vessels, strengthening bone and repairing damaged spinal cords and brain are appearing almost weekly, according to Vogel. However almost all of this research has involved mice, and tests with human ES cells may prove to be a far different story. Preliminary work shows that human cells grow more slowly and divide less predictably in cultures than do mouse cells. And once transferred into test animals, human ES cells often take a path quite different than those followed by their mouse counterparts.

Workers say so little is known about the biochemical pathways that trigger ES cells to develop into a given tissue that human therapies are years away. This has not deterred activists, most notably actor Michael J. Fox, who suffers from Parkinson’s disease, to push for human trials as soon as possible.

In some exciting work just published, Eva Mezey of the National Institute of Neurological Disorders and Stroke has shown bone marrow cells from healthy mice, when transferred into mice with depressed immune systems, partially went to grow neurons in the animals. This was a complete surprise since the popular belief is that mammals do not produce any new neurons after early stages of development, let alone that bone marrow cells could perform such a feat.

In other work, researchers at London’s Imperial College School of Medicine found that male bone marrow cells transplanted into women patients developed new liver cells with the Y chromosome that only could have come from the male donor cells. Still, as many failures as successes have been recorded, a German researcher said, “It looks like it is really difficult to differentiate human ES cells into more advanced cell types.”

But, with the restrictions on research being lifted, a breakthrough may be closer than thought even a year ago.

Clair Wood taught physics and chemistry for more than a decade at Eastern Maine Technical College in Bangor.