First cloned primate embryos
Thursday, 15 November, 2007
US scientists have for the first time created embryonic stem cell lines from a primate using somatic cell nuclear transfer (SCNT).
Therapeutic cloning has been achieved in other mammals, including Dolly the sheep, but never before in a primate. Extracting embryonic stem cells from the cloned embryos has only been successful in mice.
Shoukhrat Mitalipov and colleagues from the Oregan Health & Science University have now described a method of reprogramming adult rhesus macaque fibroblast cells into early embryonic cells.
Their findings will be published in Nature next week.
"We have been able to derive two embryonic stem cell lines," Mitalipov said.
"These cell lines ... have been able to develop into various tissues ... in vitro and in vivo. This is proof of principle that you could get reprogramming using somatic cell nuclear transfer technology."
The team generated two embryonic stem cell lines from 304 oocytes from 14 rhesus monkeys, meaning a very low efficiency of 0.7 per cent.
The cell lines, dubbed CRES-1 and CRES-2 (cloned rhesus embryonic stem) were found to have the same nuclear DNA as the donor male and the same mitochondrial DNA from the oocyte donors.
The findings have been independently validated by David Cram, Bi Song and Alan Trounson from Monash Immunology and Stem Cell Laboratories at Monash University.
The team also describes an improved method for SCNT. They suspected that the use of a particular stain and ultraviolet light during the oocyte enucleation process was harming blastocyst formation, so have instead used a new imaging system to visualise chromosomes.
Mitalipov said his lab was currently trying to create cloned rhesus macaques with genetic modifications to create a disease model for study.
The team is only working with monkeys and is not looking at humans, but he hopes the technology will be used by other labs working on human subjects, with human eggs and human cells.
"The technology we have developed for reprogramming adult somatic cells into pluripotent cells can be directly applicable to humans," he said.
"The efficiency is still quite low but we think it will work in humans."
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