Vancouver  - BC Cancer Agency scientists have determined that unlike Dolly, the sheep cloned by Scottish scientists three years ago, cows cloned by American researchers do not have shortened telomeres. This important finding may help fuel more worldwide research into combating age-related diseases by turning back the genetic clock.

Telomeres are the threads of DNA that "tie-up" or "cap" the ends of chromosomes to protect the genetic coding information of the inner DNA. Each time a cell divides, the telomeres become shorter (in other words the older the cell, the shorter the telomeres). In this way, telomere length is linked to a cell's age.

When Dolly was cloned from a cell in breast tissue of a six-year-old sheep, she was born with six-year-old telomeres which appeared shorter than those found in the cells of normal sheep. Scientists then questioned whether cloned animals would be sicker, age faster or die sooner than their natural-born siblings, and whether it would indeed be possible to turn cells back to a younger state through cloning -- an area long thought to hold promise for future human medical treatment.

BC Cancer Agency senior scientist Dr. Peter Lansdorp was approached by Advanced Cell Technology of Massachusetts to examine the cells from six healthy cows the company had cloned, after Dr. Lansdorp and his team at the Terry Fox Lab pioneered novel and comprehensive methods to measure the length of telomeres.

The results of Dr. Lansdorp's study indicate that unlike Dolly, telomere length in these cloned cow cells was actually elongated, not just maintained.

"Previously it was thought that only the cells that produce sperm and eggs, as well as cancer cells, could elongate or maintain telomeres," stated Dr. Lansdorp. "But our findings clearly show that telomeres can be elongated by cloning as well."

"It is interesting that the increase in telomere length corresponds precisely to an increased ability of the cells to divide in Petri dishes," he added. "This research suggests that cloned cows might actually live longer than cows conceived naturally."

The ability to rejuvenate animals and cells may have important implications for medicine and the study of aging, according to Dr. Lansdorp. He adds, however, that questions still remain as to how these findings can be exploited for novel therapies.

"We now need to figure out how to produce transplantable cells from cloned cells in the laboratory, how to elongate telomeres in normal cells, and how to stop telomere maintenance in cancer cells," Dr. Lansdorp added.

Advanced Cell Technology (www.advancedcell.com) which cloned the cows and provided the Lansdorp team with the cells to measure is focusing its research on the application of cloning technology in medicine and agriculture.

The research findings of Dr. Peter Lansdorp, who has been studying telomere length and its connection to aging and cancer tumour growth for the last five years, will be published April 28th by the American Association of Advancement of Science (www.aaas.org) in its prestigious journal, Science. (www.sciencemag.org).

For a copy of the AAAS news release on the paper Extension of Cell Life Span and Telomere Length in Animals Cloned from Senescent Somatic Cells, visit www.eurekalert.org