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More ethical stem cells?
Stem cells take center stage again
As usual, the big news is stem cells (click here to learn some basics about stem cells). Stem cells hold the promise to cure previously incurable conditions like spinal cord injuries and diabetes by growing new tissues. The stem cells that hold the most promise are also the most controversialembryonic stems cells.
Embryonic stem cells are controversial for a couple of reasons. First off, in the past an embryo has had to be destroyed to get its stem cells. To people who view the 8-cell embryo as a life, this is not acceptable.
The other concern revolves around the fact that the most useful embryonic stem cell will be one that has the patient's DNA. These "personalized" embryonic stem cells won't suffer from the rejection problems doctors see with organ transplants (click here to learn more about personalized stem cells). Because any tissue grown will have the same DNA, the patient's body is happy to welcome home the new heart or kidney or
The best way to get embryonic stem cells from an adult right now is to essentially turn one of his or her cells into an embryo. The risk is that some unscrupulous doctor won't stop at the embryo and will grow a clone of the patient. No reputable scientist would do this but the risk is there.
There were two major stories this week that try to address these concerns.
Harvesting cells without destroying the embryo
This week scientists were able to get stem cells from a mouse embryo without destroying it. In fact, the mouse pup was born healthy and happy. How did they do it?
The scientists used just one cell out of a mouse embryo at the 8-cell stage to create a stem cell line. The other 7 cells were put back into the mom and allowed to grow into a mouse pup.
The single cell they took out was then allowed to grow and divide many times over creating an embryonic stem cell line. The scientists showed that the stem cells could become nerve, heart and other tissues. In other words, they created a stem cell line without destroying the embryo.
The technique they used is similar to one used in people called preimplantation genetic diagnosis (PGD). With PGD, a single cell is removed from a number of human embryos. Each single cell is tested for a variety of genetic diseases and only the embryos that do not have the genetic disease(s) are put back into the mother.
What if instead of testing the cell, the doctor gave it to a scientist to grow into an embryonic stem cell line? A human embryonic stem cell line would be created without destroying the embryo. No one knows if it will work in people but we'll probably know soon.
This is an amazing stride forward. Not only do we have a source of embryonic stem cells, but the embryo now has an embryonic stem cell line perfectly tailored to him or hera personalized stem cell (click here to learn more about personalized stem cells).
As I said in the introduction, personalized stem cells have the same DNA as the patient so there is little risk for rejection. This makes them invaluable for treating spinal cord injuries or repairing heart damage after a heart attack, for example.
While this technique is wonderful for the embryo and stem cell research, it doesn't do much for those of us already here who might need personalized stem cells. The next article tries to eliminate one of the major risks in the creation of personalized stem cells.
Personalized stem cells are stem cells that have your DNA (click here to learn more about personalized stem cells). We can pretty easily get the adult version of stem cells from our bone marrow, fat or many other kinds of tissue. But we haven't found stem cells in every tissue yet. That is what makes embryonic stem cells so powerfulwe can turn them into the tissues we need.
But how do you get embryonic stem cells from an adult? One way is to clone them. Don't worry, I don't mean all the way to a baby. The idea is stop at the embryo stage. They can then harvest the cells from the embryo and get personalized embryonic stem cells.
One of the concerns with this procedure is that someone might not stop at the embryo stage and instead try to actually clone someone. This is a small but real risk in the procedure.
To get around this, scientists have created mouse embryos that can't grow in a womb. But the embryo can still yield embryonic stem cells. How'd they do this?
They started out by taking a cell from a mouse. Almost any old cell will do since most of them have the exact same DNA.
The scientists then blocked the activity of a single gene in this cell. The gene is critical for growing in a womb. This cell won't get us any embryonic stem cells on its own, though.
To get embryonic stem cells you need to start off with a fertilized egg. So, the scientists make one using the DNA from the treated cell. They take the DNA out of a mouse egg and put the cell's DNA in. You now have a "fertilized" egg that can be coaxed into growing into an embryo.
When they tested this embryo, they found that they could get embryonic stem cells from it and that it wouldn't grow into a mouse. If this technique works in humans, scientists will be able to create personalized embryonic stem cells without the risk of the patient meeting his clone one day.
This certainly gets around the problem of someone being tempted by the idea of cloning someone. But it doesn't do much for people who think that destroying an embryo is ethically wrong.
You are still creating something and destroying it later. Just because you cripple it so it can't survive, is that any different from destroying it?
There are still tough ethical questions like this out there. But at least scientists are starting to address them.
And if scientists perfect creating embryonic stem cells without destroying the embryo, babies born in the not too distant future may have personalized stem cells and all the rewards that go with them. And none of the ethical dilemmas.
This project was supported by the Department of Genetics, Stanford School of Medicine. Its content is solely the responsibility of the authors and does not necessarily represent the official views of Stanford University or the Department of Genetics.