Embryonic Stem Cell Research: A Reality Check

Date: 03/02/2002

Embryonic stem cell research is often hailed as having brought us to the brink of curing numerous diseases, including Alzheimer’s, Parkinson’s, diabetes, spinal cord injury and diseases of the heart. But despite the extravagant claims, there are numerous obstacles to therapeutic use of human embryonic stem cells, whether they are derived from frozen embryos, or from cloned human embryos.

These very real drawbacks rarely receive the same public attention as the purely speculative claims regarding the potential benefits. As John Chute, then head of the Hematopoietic Stem Cell Studies Section at the Naval Medical Research Center, testified before Congress in September 2001: “These limitations of embryonic stem cells as a source of tissue for human transplantation should be openly and honestly presented to the public, since treatments and cures from these cells are not imminent.” And the New York Times has reported that cures from human embryonic stem cells “if it ever happens, it will not happen soon–although they worked with mouse embryonic stem cells for 20 years and made some progress, researchers have not used these cells to cure a single mouse of disease,” (“A Thick Line Between Theory and Therapy, as Shown with Mice,” 12/18/01).

In fact, problems associated with embryonic stem cells include:

Difficulty in Establishing and Maintaining Embryonic Stem Cell Lines

“‘Simply keeping human embryonic stem cells alive can be a challenge,’ says Peter Andrews of the University of Sheffield in England. For more than a year, he and his colleagues have been experimenting with embryonic stem cell lines that James Thomson derived at the University of Wisconsin, Madison. ‘They’re tricky,’ Andrews says. It took several false starts–and a trip to Wisconsin –before the researchers learned how to keep the cells thriving, he says. [Harvard’s Douglas] Melton uses almost the same words: Human embryonic stem cells ‘are trickier than mouse,’ he says. ‘They’re more tedious to grow.'”

–“Stem cells: New excitement, persistent questions,” Science 290, 1672-1674; 12/1/00

“Only one [embryonic stem cell line] works well,” he said. “The others, they have all kinds of different problems. They either don’t grow well or they differentiate spontaneously, kind of like popcorn popping before you’ve added heat…In my view [human embryonic stem cells’] properties will degrade with time. Everyone is fearful that the more you grow them in the dish, the more they lose their properties.”

–Doug Melton, Harvard University researcher, quoted in the “Stem Cell Decision Examined,” the Washington Post, 8/12/01

“[T]he poor availability of human oocytes, the low efficiency of the nuclear transfer procedure, and the long population-doubling time of human ES cells make it difficult to envision this [embryo cloning to produce stem cells] becoming a routine clinical procedure…”

–J.S. Odorico, D.S. Kaufman, J.A. Thomson, “Multilineage differentiation from human embryonic stem cell lines,” Stem Cells 19, 193-204; 2001

“…[T]he use of such therapeutic cloning to produce useful treatments may simply be impractical… ‘It’s too laborious and costly to employ as a routine therapeutic procedure,’ said Dr. Alan Colman, research director at PPL Therapeutics, the Scottish company that helped clone Dolly the sheep…For one thing, unless success rates improve dramatically, the therapeutic cloning will require a large number of eggs