Scientists Report Advances in Stem Cell Technology

Two groups of researchers, one in the United States and the other in Japan, recently announced progress in stem cell technology that could have implications for future applications of stem cells to disease treatment.

Embryonic stem cells have been proposed as a way to treat neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), because they’re presumably capable of becoming various kinds of cells in the nervous system.

To treat muscle diseases, most researchers favor using cells that are a little further along in their development toward muscle than embryonic stem cells are. (Stem cells derived from people with genetic disorders, researchers caution, have the same genetic flaw that caused the disease originally and, therefore, have to be genetically altered before they can be used as therapy.)

Irina Klimanskaya and colleagues at Advanced Cell Technology, a private biotechnology company in Worcester, Mass., announced online Aug. 23 in the journal Nature that they had created embryonic stem cells from embryo “biopsies,” a technique that theoretically should leave the original embryo intact.

Embryo biopsies, which are already in use to diagnose genetic abnormalities in embryos before they’re implanted in a woman’s uterus, take a single cell from an embryo at a stage when all the cells in the embryo are alike, usually at the eight- to 10-cell development stage.

Until now, deriving a new line of human embryonic stem cells has required destruction of the embryo, to which many people are opposed.

In another development, Kazutoshi Takahashi at Kyoto (Japan) University and Shinya Yamanaka at the Japan Science and Technology Agency in Kawaguchi announced in the Aug. 25 issue of the journal Cell that they’ve succeeded in deriving cells that behave much like embryonic stem cells from mouse skin cells.

Reasoning that the difference between a cell that’s “pluripotent,” or able to mature into a variety of cell types, and one that isn’t, is based on the presence or absence of certain genes, they selected 24 candidate genes that carry instructions for proteins that induce pluripotency.

They narrowed the necessary genes and proteins down to four, which they say can turn skin cells into “induced pluripotent stem cells” if grown under the right laboratory conditions.

They caution that they don’t know whether the technique is applicable to humans, but they say “the finding is an important step in controlling pluripotency, which may eventually allow the creation of pluripotent cells directly from somatic [not sperm or egg] cells of patients.”