Eggs-perts. Through practice with cow eggs (above) and other means, Korean researchers have increased their efficiency at cloning human embryos to create stem cells (inset).

Cloning of Human Stem Cells Speeds Up

Scientists have created nearly a dozen new lines of human embryonic stem (ES) cells that for the first time carry the genetic signature of diseased or injured patients. The breakthrough represents a dramatic increase in the efficiency of creating such lines and may eventually pave the way for treating conditions such as spinal cord injury with stem cell transplants.

Last year, a group led by veterinarian Woo Suk Hwang and gynecologist Shin Yong Moon at Seoul National University reported the first derivation of ES cells from human nuclear transfer (Science, 12 March 2004, p. 1669)--a process that involves replacing an oocyte's nucleus with one from a different cell, and then chemically kick-starting development of the egg. But those efforts yielded just one cell line from more than 200 tries.

In the new study, reported online today in Science (article is free with registration), the same team increased their efficiency more than 10-fold and can now derive cell lines in more than 1 in 20 tries. Part of the secret is that they used freshly-harvested oocytes from young, fertile women instead of oocytes left over from fertility treatments. In nine cases, it took only a single donation of oocytes from a woman to produce a new line. Nine of the 11 cell lines are derived from patients who have suffered spinal cord injuries, ranging in age from 10 to 56. The other lines are derived from 2-year-old boy with a genetic immune disorder and a 6-year-old girl with Type-1 diabetes.

Hwang cautions that his team remains years away from transplanting the cells into people. "We have to be over-convinced" that the cells are safe, he says. However, the cell line derived from the diabetes patient should be of great interest to scientists.

"The possibility of being able to study disease in a culture dish is very exciting," says Douglas Melton, who has recently received permission from a university ethics committee to derive ES cells from diabetes patients in his laboratory at Harvard. "For the first time, we will have a chance to study the root causes of the disease."

The new results may also influence the ongoing political debate over whether research with human embryonic stem cells, cloned or not, is ethically justified. "Some people will hate it, others will love it," says Rudolf Jaenisch of the Massachusetts Institute of Technology. "But it puts the discussion on a very firm footing now. People will have to rethink the argument that it's not efficient."

Related site
Overview of cloning from the National Human Genome Research Institute

Posted in Biology