‘Versatile Cells’ Sidestep Ethical Disputes

On June 7, American and Japanese scientists reportedly succeeded in producing ‘versatile cells,’ which act as embryonic stem cells. The cells are produced by manipulating genes in somatic cells without human eggs.

Foreign outlets and the New York Times reported that the new technique will open new possibilities in stem cell research and will avoid all or almost all ethical criticism directed at the use of embryonic stem cells

Embryonic cells without using egg cells-

Three research teams (led by Shinya Yamanaka of Kyoto University, Konrad Hochedlinger of Harvard Medical School, and Rudolf Jaenisch of the Whitehead Institute) said they succeeded in reprogramming skin cells. They injected four genes into skin cells and reverted to cells indistinguishable from embryonic stem cells. The process does not involve eggs, embryos or nuclear transfer.

The Japanese and Whitehead Institute teams published their findings in Nature, and Harvard team in the inaugural magazine ‘Cell Stem Cell.’

The three teams injected four genes (Oct4, Sox2, c-Myc, Klf4), which are activated at an embryonic cell stage, into skin cells of mice to promote adult cells reverting to primary cells, which are cells before they develop into specific organs.

The primary cells develop into many body tissues, such as the heart, liver, and kidney. The teams have named the cells in-plane switching (iPS). Since they are similar to embryonic cells, they are different in kind.

The technique was initially announced by Professor Shinya Yamanaka of Kyoto University. However, it did not get due attention as it was discovered right after the Korean stem-cell scandal from Hwang Woo-seok.

A breakthrough in stem cell research-

Experts say the outcome is a breakthrough that gets over limits in embryonic and adult cell research.

Previously, the only way to convert adult cells to embryonic form has been by nuclear transfer, the insertion of an adult cell’s nucleus into an egg whose own nucleus has been removed. The egg somehow reprograms the nucleus back to an embryonic state. The embryo can develop into any tissue, but the procedure inevitably destroys embryos, raising an ethical dispute. Also, it requires a large number of human eggs.

On the other hand, adult stem cells extracted from bone marrow and umbilical cord cells are free from ethical controversy. They, however, are available only from certain organs and do not develop into many organs.

Otherwise, iPS uses body cells only and easily produces a massive number of stem cells. And it can produce ‘tailored cells’ for patients without resistance as it uses the patient’s cells. Gene transfer is technically easier than nuclear transfer.

Park Se-pil, the director of the Stem Cell Research Center at Jeju University, said, “Using only somatic cells and producing cells the same as stem cells is a great achievement. Necessary cells are easily available from skin in large volumes, and no resistance and technical ease are strengths.”

The Wall Street Journal (WSJ) expects that the technique will ease the ethical controversy over stem cell research. The WSJ also estimates relevant research to increase in the near future. Still, the new procedure faces an uphill battle to be adaptable to human cells.

The New York Times points out that the technique is likely to cause cancer and mutations through viruses, indicating much room for improvement.

redfoot@donga.com