Artificial Reproduction, Assisted Reproduction, Bioethics, cloning, public policy, regenerative medicine

Scientific American: Cloning is inefficient

Okay, that wasn’t the intended point of the Scientific American news article. While it should have been, the actual point that I think the authors here wanted to make (besides pushing embryonic stem cells, in the first place) was: Adult stem cells don’t do as well as fully-differentiated White Blood Cells in SCNT experiments in mice.

Not really much new:

Cloning relies on a process known as somatic cell nuclear transfer, in which the nucleus of a donor cell is transferred into a fertilized egg that has been emptied of its chromosomes.

As I said, that’s not news. We have further evidence that progenitor cells and stem cells don’t work as well as adult, differentiated cells which don’t work as well as embryonic cells in SCNT to produce blastocyts and birth.

The experiment was done in mice: no one has been able to get to the blastocyst stage in humans, yet. And, so far, we need embryos that will grow at least 4 to 5 days to get embryonic stem cells. (Even in ACT’s supposed “ethical” method, where the embryos were killed even though the researchers swear they didn’t have to.)

Embryonic stem cells succeeded 49% in SCNT. But, that won’t be much help in grown-up, sick humans.

I didn’t do all the math. But, 1368 white blood cell nuclei were transferred to enucleated oocytes: 34% developed to blastocyst stage – only 2 were born. Both died soon after.

1368 eggs. For only one leg of this experiment. Granted, these aren’t human eggs and Hwang used over 2200 actual human oocytes.

At the end of the article is the part that is the most interesting to me:

Yang’s team showed that cloning from such cells succeeded in 49 percent of attempts and led to 18 mouse pups. Of course, such embryonic stem cells are not available in adult patients, so being able to create them from regular cells is an important step. But mystery still surrounds the best way to clone. “We think that adult stem cells are more quiescent; we think that it’s like a locked, closed door,” Yang explains. “We think that differentiation is a way that opens some doors and makes it easier for nuclear transfer programming to go back into embryonic stem cells.”

“We have some very encouraging data from an ongoing study that you can modify the status of cells and increase the efficiency of cloning,” he adds. “If we modify the epigenetic status,” that is, turning certain genes on or off, “it could be that you could increase the efficiency. This opens the door for a lot of different studies.” The odds are that Dolly’s genome came from a differentiated cell, but the quest for the best way to create cloned animals continues.

Please note that the emphasis is mine and that last sentence comes from the author of this “news” piece, not from the researcher, Yang.

As James Thomson said last month
, if we learn to change which genes are turned off and which ones are turned on, perhaps we can learn to make embryonic-like cells that will form the tissue lines we desire, without ever forming or risking the lives of embryonic humans.

About bnuckols

Conservative Christian Family Doctor, promoting conservative news and views. (Hot Air under the right wing!)


No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

If the post is missing: take the “www.” out of the url




%d bloggers like this: