Embryonic stem cells made without destroying embryos
Bob Lanza, scientific head of ACT, says he's generated three embryonic stem cell lines without destroying embryos. These would be the first embryonic stem cell lines ever made where an embryo wasn't destroyed. In fact, he's waiting to see if the NIH will fund research on these lines on the grounds that, since no embryo was destroyed, these lines should be eligible for federal grants. Other scientists at the meeting are skeptical. They say they need to see data.
Under Lanza’s technique embryos are grown to the 8-cell stage, then one cell is removed, the embryo and blastomere grown side by side until the embryo reaches the blastocyst stage and can be frozen. The cells from the blastomere are used to generate embryonic stem cells. Last August, Lanza's work caused a furor when his team derived human embryonic stem cells from single cells taken from early embryos. The study was proof-of-priniciple that embryos did not have to be destroyed, but the work did in fact destroy embryos, so that fewer embryos could be used.
http://www.nature.com/news/2006/060904/full/443012a.html
Since these cell lines are derived without destryoing an embryo, Lanza says, NIH should fund them. In fact, he says he's applied for a grant with Susan Fisher from UCSF who's generated pluripotent lines from placenta and Tony Atala from Wake Forest who's generated pluripotent lines from amniotic fluid to compare the lines side by side.
He would only say that the efficiency was very low, but a little higher than what had been reported in August 2006. It's definitely lower than with blastocysts.
Lanza is making lots of claims here, but hasn’t provided data yet. He says the blastomere-derived cells are five times as efficient at making hemiangioblasts as typically used NIH lines and also better at making neurons.
The point of this is not to ask new scientific questions but to get around the letter of the law that bans federal research funding for work that destroys an embryo. "What this particular work is a trial balloon to some extent," he said. "I feel like I’m standing on my hands to try to please them." He says he submitted the grant in February and the NIH still hasn't decided if these cells are eligible for funding.
Lanza imagines that stem cell lines could be made when an embryo is subjected to preimplantation genetic diagnosis (PGD), in that one cell of an 8-cell embryo is removed and tested. He imagines that that cell, or, rather, cells derived from it could both be tested and used to generate embryonic stem cell lines, but he says he’s not planning a paid service where would-be parents would order an embryonic stem cell line along with PGD. He said there were ethical issues there.
But the blastomere and the seven-cell embryo would have to grow side by side for two or three days, and it’s not clear the PGD is the best option unless certain risk factors are in place. See Bruce Goldman’s piece in Nature last February and in the LA Times: http://www.latimes.com/features/health/medicine/la-he-pgd23apr23,1,5376531.story?coll=la-health-medicine
http://www.nature.com/nature/journal/v445/n7127/full/445479a.html
I talked to four scientists at the meeting and none seemed horribly impressed. Probably, no would-be parent would implant the blastocysts.
Comments
I am not against stem-cell research per se but can anyone please explain where the scientific evidence is that embryonic stem-cells can do anything that adult stem cells cannot?
If it is unnecessary why do it?
Posted by: Nick Henriquez | June 21, 2007 10:07 AM
to Nick -
you mean therapeutic potential I guess. Here ES and adult SC hard to compare, second one much more powerful and so many clinical trials going on around the world. In case of ES it's will be very long way to go, and probably ES and derivates transplantation will never consider clinically reasonable.
In other hand ES cells - irreplaceable and unique tool for drug testing, gene targeting, best model of human development in embryology and basic science.
So of course we need them both - ES and adult SC - we need them like an air, it's out of discussion.
"It's not debate in scientific community (ES vs ASC), it's debate in public and mass media" (James Tomson)
Posted by: nanog | June 29, 2007 05:58 AM
nanog's right. There's no debate among scientists about the need for both. However, you asked for evidence, so I'll point you to some. Adult Stem Cells are capable of multilineage differentiation, but they are restricted from crossing certain developmental barriers that aren't present in ESCs. The best place to start reading about this is the work of Rudy Jaenisch, specifically as regards genomic imprinting, nuclear reprogramming, and epigenetic control of gene expression.
Posted by: Mr. Gunn | June 29, 2007 03:55 PM
An important difference between hES cells and adult stem cells is that ES cells are much more "expandable". Since they self renew rapidly under the right conditions, it is possible to start with just a plateful of cells and potentially scale up to sufficient quantities to carry out a drug screen, and for transplantation (although it remains to be seen if this strategy will work-- however Geron is initiating a clinical trial to see if hES-cell derived oligodendrocytes can help patients with spinal cord injury).
Adult stem cells, on the other hand, tend to grow more slowly, even though it is easier to get them to form differentiated cell types. No one has figured out a good way to expand cord blood stem cells so that a fully grown human adult can benefit from their storage.
As I see it, those are the most important differences between the two cell types right now.
Posted by: Natalie DeWitt | July 4, 2007 12:59 AM
We must stand up to the radical right and say an embryo is not a person and can be used for research. The truth is that every cell of an early zygote, separated from it is a zygote itself. Bob Lanza may not have destroyed the original embryo but the cell that he took out becomes a "harmed embryo". Only political activism will solve the problem
Posted by: Claude Gerstle | August 2, 2007 01:11 AM