So this week, we're talking about cloning.
A couple weeks ago, a team from Oregon published a paper
describing their successful creation of human embryonic
stem cells from cloning.
Called somatic cell nuclear transfer,
the process combines a somatic donor cell with all of its DNA
with an enucleated donor egg.
So this means a donor egg which has had its DNA and nucleus
removed.
When successful, of the egg will take the donor DNA,
turn it back to an unprogrammed embryonic state,
and then the combined cell will go forwards, divide,
and form a blastocyst.
From here, cells can be cultured, harvested,
and turned into almost any cell type in the body,
allowing doctors to create patient-specific tissues.
So this process sounds familiar.
That's great.
It should.
This is the same process that was used to create Dolly
the clone sheep many years ago.
And since it's been working in animals for a while
and the researchers who wrote this paper actually got it
working in monkeys about six years ago,
but it took them a little bit longer to get it working
in human cells.
But it may also sound familiar because it has the same goals
as another technology I talked about about two weeks ago--
induced pluripotent stem cells.
Both of them aim to create patient-specific cells,
tissues, and organs.
But these cloned NTST cells are a little bit different
because they require the use of a donor egg,
which is not only expensive but also means that
the mitochondrial DNA in these newly formed cells is not from
the DNA donor, but instead it is from the egg donor.
Now if you don't recall it mitochondrial DNA is,
I talked about it a little while back,
and it's a specific type of DNA found in your mitochondria.
Now this is passed down maternally because when sperm
and egg come together, all the mitochondria that you or most
of the mitochondria that you get are actually held in that egg.
Very, very few of them come from the sperm
because they're in the cytoplasm of the egg.
So this means that this is DNA specifically inherited through
the mother.
Now that's really interesting because when you have this
enucleated egg cell in NTST cloning,
and then you introduce this I donor cell,
it means that your mitochondria are still from that donor egg.
And so this is really kind of an interesting thing
because you're creating tissues which have the nuclear DNA
of your donor cell but which have the mitochondrial DNA
of the egg donor.
And I just think that's an interesting thing to consider
going forwards.
So not only do I get cells of the same mitochondrial DNA
as that patient or donor that you're trying to create new
cells and tissues for, but they also don't require the use
of a donor egg.
And so they circumvent the legal and ethical issues as well
as the expense of using eggs and creating embryonic stem cells.
A scientist quoted in the nature news article about this recent
publication remarked, "The most surprising thing about this
paper is that somebody is still doing human SCNT in the era
of IPS cells."
And I agree with him.
Now since this paper has come out,
some questions have arisen.
An anonymous online commenter pointed out the fact that there
were some problems with the paper that there were some
duplicated data and some mislabeled images.
It appears that in their haste to publish,
some things were mixed up.
Now the lab is still insisting that the data is real and that
the cell lines were actually created.
And I believe that, and I don't think anyone is arguing
at the moment that that is untrue.
But there was such a haste to publish that the normal review
period was dramatically reduced.
And I don't think that this article got the same sort
of critical fine-toothed comb review that most articles
published in major journals do.
There was only a three-day period between when they
submitted the paper and when it was accepted.
And then only 12 days after that, it was published.
And this is crazy.
I've been through the article publication process before,
and it took months.
You submit your paper.
It goes up for review.
People request changes.
You make those changes, and then you put it in again.
And then it gets accepted in principle,
and then there are more months until it gets actually
published.
And it's just-- it's crazy.
And I think this stands as a really good point that science
takes time, and reviewing science takes time.
And those things-- that time period--
those time periods are there for a reason.
I think this is also a great reminder that you should always
read and watch things critically and sometimes even a little bit
skeptically.
Now I'm again not saying that I think that what happened
in the paper was incorrect, but I think that when
you're looking at something, it's really important that you
look at the data for yourself and you form your own opinions
about it.
Now this is really important in life,
and it's also important stuff like this so that people can
find those mistakes and make sure they get sorted out
and make sure that everything is OK,
make sure that things are good.
And it's a really important skill.
And I will admit I went through this paper with my happy green
highlighter, and I didn't catch the mistakes.
And maybe that was sloppy of me.
But I think it's really important to not just read
the news articles about these things and not just watch
videos on them but to know how to be able to go back to that
source on your own and look through it and really be able
to critically think about what is being presented to you
and what you're going to do with that information.
So in sum, we've made cloned human embryonic stem cells,
but I still don't think it's quite as cool as induced
pluripotent stem cells.
And remember to always critically read and watch
as you go forth and do science.