Stem-Cell Advance Made
Using Monkey Embryos
By GAUTAM NAIK
November 14, 2007 9:31 a.m. [WSJ]
Researchers have created embryonic clones of monkeys and derived viable stem-cell lines from them, a feat that has long eluded science. Because primates are our not-too-distant cousins, scientists hope that the same technique may one day help create patient-specific stem cells and treat diseases without triggering an immune response.
The achievement with rhesus macaque monkeys was first disclosed at a scientific meeting in Australia in the summer, but the details had not yet been validated by other researchers. The peer-reviewed data have now been published in the Web site of Nature. The journal carries a separate paper by independent scientists who experimentally validated the cloning work.
In their paper, a team that includes Shoukhrat Mitalipov of the Oregon National Primate Research Center, said it had created monkey clones by using a variation of the process that led to the creation of Dolly the sheep, the first cloned mammal. Although scientists have since cloned a wide range of species, including cows, cats and dogs, they have struggled to do the same with primates.
Dr. Mitalipov and his colleagues injected the genetic material from a skin cell of an adult monkey into a monkey egg whose own DNA had been removed. They then induced an early-stage embryo called a blastocyst, and derived stem cells from it. According to the paper, the team generated two embryonic stem cell lines from more than 300 eggs taken from 14 rhesus monkeys.
The results "demonstrate proof-of-concept for therapeutic cloning in primates," concludes the Nature paper.
Therapeutic cloning in humans is the ultimate goal. The idea is to create a similar early-stage clone of a patient and tease out the embryonic stem cells. In the lab, these can then be persuaded to turn into specific cell types, such as heart, nerve or muscle. When transplanted into the patient, the tissue won't face immune rejection because its DNA exactly matches that of the patient donor.
Therapeutic cloning has long been ethically controversial because early-stage human clones get destroyed when stem cells are extracted from them. Others fear that knowledge of the process could allow renegade scientists to take an early-stage cloned blastocyst to term, thereby creating a full-fledged human clone.
The field has been under a cloud for other reasons. In 2005, Korean researcher Hwang Woo Suk created a stir by publishing a paper in Science claiming that his team had extracted material from cloned human embryos that identically matched the DNA of 11 patients. Those results were later shown to be fabricated, and the paper was retracted.
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