Featured Research

from universities, journals, and other organizations

Stem Cell Breakthrough: Researchers Offer Proof-of-concept For Altered Nuclear Transfer

Date:
October 17, 2005
Source:
Whitehead Institute for Biomedical Research
Summary:
Scientists at Whitehead Institute for Biomedical Research have successfully demonstrated that a theoretical--and controversial--technique for generating embryonic stem cells is indeed possible.

Scientists at Whitehead Institute for Biomedical Research havesuccessfully demonstrated that a theoretical--andcontroversial--technique for generating embryonic stem cells is indeedpossible, at least in mice.

The theory, called altered nuclear transfer (ANT), proposes thatresearchers first create genetically altered embryos that are unable toimplant in a uterus, and then extract stem cells from these embryos.Because the embryos cannot implant, they are by definition not"potential" human lives. Some suggest that this would quell theprotests of critics who claim that embryonic stem cell researchnecessitates the destruction of human life. Scientists and ethicistshave debated the merits of this approach, but so far it has not beenachieved.

"The purpose of our study was to provide a scientific basis forthe ethical debate," says Whitehead Member Rudolf Jaenisch, lead authoron the paper that will be published in the October 16 online edition ofthe journal Nature. "Our work is the first proof-of-principle study toshow that altered nuclear transfer not only works but is extremelyefficient."

First proposed by William Hurlbut, Stanford Universityprofessor and member of the President's Council on Bioethics, ANT hasbeen described as an ethical alternative to somatic cell nucleartransfer (SCNT), also known as therapeutic cloning.

For SCNT, a donor nucleus, for example one taken from a skincell, is implanted into a donor egg cell from which the nucleus hadbeen removed. This egg cell is then tricked into thinking it has beenfertilized. That causes it to grow into a blastocyst--a mass of about100 cells--from which stem cells are removed. These embryonic stemcells can divide and replicate themselves indefinitely, and they canalso form any type of tissue in the human body. However, to cull thesestem cells, the blastocyst must be destroyed, which some critics insistis tantamount to destroying a human life.

The procedure theorized by Hurlbut is similar to SCNT, butwith one crucial twist: Before the donor nucleus is transferred intothe egg cell, its DNA is altered so that the resulting blastocyst hasno chance of ever becoming a viable embryo. As a result, a "potentialhuman being" is not destroyed once stem cells have been extracted.

Jaenisch--a firm supporter of all forms of human embryonicstem cell research--has shown that technical concerns about thisapproach can be overcome.

Jaenisch and Alexander Meissner, a graduate student in hislab, focused on a gene called Cdx2, which enables an embryo to grow aplacenta. In order to create a blastocyst that cannot implant in auterus, the researchers disabled Cdx2 in mouse cells.

They accomplished this with a technique called RNAinterference, or RNAi. Here, short interfering RNA (siRNA) moleculesare designed to target an individual gene and disrupt its ability toproduce protein. In effect, the gene is shut off. Jaenisch and Meissnerdesigned a particular form of siRNA that shut off this gene in thedonor nucleus and then incorporated itself into all the cellscomprising the blastocyst. As a result, all of the resulting mouseblastocysts were incapable of implantation.

However, once the stem cells had been extracted from theblastocysts, Cdx2 was still disabled in each of these new cells,something that needed to be repaired in order for these cells to beuseful. To correct this, Meissner deleted the siRNA molecule bytransferring a plasmid into each cell. (A plasmid is a unit of DNA thatcan replicate in a cell apart from the nucleus. Plasmids are usuallyfound in bacteria, and they are a staple for recombinant DNAtechniques.) The stem cells resulting from this procedure proved to bejust as robust and versatile as stem cells procured in the moretraditional fashion.

"The success of this procedure in no way precludes the need topursue all forms of human embryonic stem cell research," says Jaenisch,who is also a professor of biology at MIT. "Human embryonic stem cellsare extraordinarily complicated. If we are ever to realize theirtherapeutic potential, we must use all known tools and techniques inorder to explore the mechanisms that give these cells such startlingcharacteristics."

ANT, Jaenisch emphasizes, is a modification, but not analternative, to nuclear transfer, since the approach requiresadditional manipulations of the donor cells. He hopes that thismodification may help resolve some of the issues surrounding work withembryonic stem cells and allow federal funding.

###

This research was supported by the National Institutes of Health/National Cancer Institute.



Story Source:

The above story is based on materials provided by Whitehead Institute for Biomedical Research. Note: Materials may be edited for content and length.


Cite This Page:

Whitehead Institute for Biomedical Research. "Stem Cell Breakthrough: Researchers Offer Proof-of-concept For Altered Nuclear Transfer." ScienceDaily. ScienceDaily, 17 October 2005. <www.sciencedaily.com/releases/2005/10/051017064825.htm>.
Whitehead Institute for Biomedical Research. (2005, October 17). Stem Cell Breakthrough: Researchers Offer Proof-of-concept For Altered Nuclear Transfer. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2005/10/051017064825.htm
Whitehead Institute for Biomedical Research. "Stem Cell Breakthrough: Researchers Offer Proof-of-concept For Altered Nuclear Transfer." ScienceDaily. www.sciencedaily.com/releases/2005/10/051017064825.htm (accessed July 22, 2014).

Share This




More Health & Medicine News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
Contaminated Water Kills 3 Babies in South African Town

Contaminated Water Kills 3 Babies in South African Town

AFP (July 18, 2014) Contaminated water in South Africa's northwestern town of Bloemhof kills three babies and hospitalises over 500 people. The incident highlights growing fears over water safety in South Africa. Duration: 02:22 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins