Rewinding The Biological Clock

The fountain of youth burbles away in egg cells, according to researchers at Advanced Cell Technologies, a biotech company in Worcester, Mass. In the Apr. 28 issue of Science, they report that cells from six cow clones show no signs of the premature aging that has affected other clones such as the sheep Dolly. In fact, their studies suggest the cloning process actually made old cells young again. "We've rewound the biological clock," says Michael D. West, ACT's chief executive officer.

The ACT scientists utilized a different method to create their clones than was used to make Dolly. They harvested DNA from skin cells at the end of their life spans and transferred it to egg cells stripped of genetic material. After the cloning process, the cells appeared to be reborn. Instead of being less than four cell divisions away from death, like the original skin cells, they survived for 90 cell divisions.

West and his colleagues aren't sure how cloning sends cells into a time warp. Nor do they know whether this process will extend the lives of animals that develop from such cells. But the results should quell rising skepticism about cloned cells' utility. West believes that someday the technique could generate a bountiful supply of healthy tissue, which could replace diseased cells in people with Parkinson's, Alzheimer's, and heart disease.

Other specialists who are familiar with the research agree. Says Leonard Hayflick, a professor at the University of California at San Francisco and an expert in aging research: "The study represents a milestone in our efforts to understand how longevity is determined."

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