Tuesday, October 26, 2004
New way to convert adult human stem cells to dopamine neuronsThose opposed to the use of embryonic stem cells (ESC) often argue that adult stem cells (ASC) offer a greater promise for therapeutic applications. At first, this perplexed me. After all, if the argument against use of ESC is based upon the notion that all embryos are human, and destruction of such embryos is absolutely forbidden, then the relative merits of the two cell types should not matter. However, I have learned that, for some people, it does matter. Some persons might argue that use of ESC is OK, if they can produce benefits that are not available by any other means. This argument might provide exceptions to the absolute ban on use of ESC. If it can be shown that all the same benefits can be derived from ASC, then there would be no exceptions that would permit use of ESC.
Posted on Monday, October 25, 2004 @ 3:30 PM PDT by bjs (Science Blog)
Researchers at Jefferson Medical College have found a new way to coax bone marrow stem cells into becoming dopamine-producing neurons. If the method proves reliable, the work may ultimately lead to new therapies for neurological diseases such as Parkinson's disease, which is marked by a loss of dopamine-making cells in the brain.
Developmental biologist Lorraine Iacovitti, Ph.D., associate director of the Farber Institute for Neurosciences at Thomas Jefferson University in Philadelphia and her co-workers had previously shown that by using a potion of growth factors and other nutrients in the laboratory, they were able to convert adult human bone marrow stem cells into adult brain cells. [...]
While nearly all cells looked like neurons with axonal processes, they invariably reverted back to their original undifferentiated state in two to three days.
Dr. Iacovitti and her co-workers instead attempted to grow the cells in a different way. Rather than an attached monolayer of skin-like cells, they grew the bone marrow cells in suspension as neurospheres -- groups of cells early in development -- akin to the way neural stem cells are grown.
They found that the newly differentiated cells didn't merely look like dopamine neurons, but expressed traits of neurons and related cells called astrocytes and oligodendrocytes -- cells derived from neural stem cells. What's more, the neurons produced tyrosine hydroxylase, an enzyme needed to make dopamine.
She reports her team's findings October 25, 2004 at the annual meeting of the Society for Neuroscience in San Diego.
The Jefferson scientists also found a second enzyme involved in dopamine production, and an important molecule called the dopamine transporter.
For some people, the finding of conclusive evidence for a therapeutic benefit from ASC might be seen as strengthening the argument that there is no justification for use of ESC. This is not really a valid line of reasoning, of course, since the potential benefits of ESC cannot be known unless research on ESC is permitted.
The second article is bad news for opponents of ESC research:
Stem cells home in on brain cancerNaturally, in order for any such therapy to work, it is essential that the patient's immune system not attack the therapeutic cells. In this particular application, it also is essential that the cells be able to migrate to the desired location. So far, ESC are the only cells that have been shown to act in this way.
Jim Giles (Nature News)
Arming embryonic stem cells with anti-cancer agent could help create new therapies.
Published online: 25 October 2004; | doi:10.1038/news041025-6
Human embryonic stem cells could be used to seek out and destroy a fatal form of brain cancer, according to US researchers.
Experiments in mice with brain tumours show that the cells will migrate across the brain and deliver an anticancer payload. Human clinical trials could begin in two years' time, the researchers said on 24 October at the annual meeting of the Society for Neuroscience, held in San Diego.
Biologist Evan Snyder modified stem cells taken from a human embryo, adding a gene that made the cells express a tried and trusted antitumour molecule known as TRAIL. When injected into mice with brain tumours, the cells homed in on the cancer and pumped out enough TRAIL to cut the tumour size by an average of 50%, and up to 70% in some cases.
The cells are thought to track the tumour by following chemical signals emitted by the immune system molecules that attack, but ultimately fail to destroy, the cancer. Snyder, who is based at the Burnham Institute in La Jolla, California, says similar behaviour has been observed in other animal models of brain injury, where naturally occurring stem cells will travel towards and attempt to repair damaged areas. [...]
Snyder adds that the work is an important proof of principle and that TRAIL is not necessarily the best way of attacking cancer. Stem cells could be modified to express other anticancer molecules, or a combination of cells, each equipped with different molecules, could be used in concert.
Switching topics, the next article pertains to human cloning research:
UN delays cloning voteThe failure of the USA to get a vote on the subject is something that may have been inevitable. However, given the disdain we have shown the UN in recent years, it is possible that our weakened position there has lessened our influence, making it less likely that we would be able to bring the matter to a vote. This, I think, demonstrates the folly of our recent move toward unilateralism. Of course, Mr. Siegel is not the only expert on the subject. But regardless of the specifics of this particular issue, the point still stands, that the best way for the Bush administration to press for pro-life issues is to enlist the cooperation of the International community.
US speaks out in support of total cloning ban, vote may take place soon
By Alison McCook (www.the-sceintist.com)
October 25, 2004
UNITED NATIONS—The legal committee of the UN's General Assembly concluded the year's second day of debating whether to ban human cloning on Friday (October 22) without taking a vote, leaving the issue to percolate further in the minds of the deeply divided—and still undecided—member states.
On Friday, Susan Moore, the US Special Advisor, addressed the committee and reiterated the country's position in favor of the total cloning ban. Therapeutic cloning turns "nascent human life into a resource or commodity to be mined and exploited, eroding the sense of worth and dignity of the individual," she said. "For this reason, a partial ban that prohibits reproductive cloning but permits therapeutic, research, or experimental cloning is unacceptable to the United States and many other countries."
The UN has been trying to reach agreement on a convention for more than 2 years. On Thursday (October 21), UN Secretary General Kofi Annan announced that he supports the use of cloning in therapeutic research, opposing the United States and more than 60 other member states that currently support a resolution proposed by Costa Rica that would ban all forms of cloning.
Some 20-odd member states have said they support a separate resolution, put forth by Belgium, which recommends a ban on human reproductive cloning and leaves the decision about therapeutic cloning up to individual states. Under this proposal, members have the option of a total ban, a moratorium on therapeutic cloning, or regulated use of the practice under legislative controls. [...]
Bernard Siegel, executive director of the Genetics Policy Institute, an organization that opposes reproductive but supports therapeutic cloning, told The Scientist he was pleased no vote was taken, given that in previous years, a majority of delegates appeared to support a total cloning ban. The longer the committee waits to vote, the more time scientists have to prove the potential of therapeutic cloning, he said. "Time gives an opportunity to educate."
Moreover, Siegel said he believed that opinion was slowly shifting away from a total cloning ban. For instance, some African nations that previously appeared to support the total ban now appear to have changed their minds. "There's an erosion of support [for the total ban]," Siegel said.
Siegel said he believed some UN member states were closely watching the results of the upcoming US election, given that the US has a strong influence, and President George W. Bush's opponent, John Kerry, supports therapeutic cloning. "If Kerry wins, they will feel less inclined to vote the way of the Bush administration," he said.
UPDATE: On 10/27/04, an article appeared on the BBC site, reporting on a case of a person whose eyesight was restored after a transplant of retinal cells taken from an aborted fetus:
US scientists have successfully restored a woman's vision using eye cells taken from aborted foetuses. But while hailing their results as a triumph, the University of Louisville researchers are worried critics will say they are promoting abortion. The UK has clear guidelines to ensure people cannot conceive and terminate a baby to treat another person, but similar rules do not exist in the US.
Again, the USA is falling behind the rest of the world, as legislation is not keeping up with scientific advances.
(Note: The Rest of the Story/Corpus Callosum has moved. Visit the new site here.)
E-mail a link that points to this post: