Not so very long ago the winners of the 2012 Nobel Prizes were announced. Two men shared the prize for medicine and physiology, John Gurdon and Shinya Yamanaka. While the details of what they won for must be quite complicated, the broad outlines are pretty easy to grasp and are actually relevant to the conversations here. I learned this yesterday listening to one of my favorite podcasts–Science Weekly from The Guardian. You can also read about their work, if you prefer but I found the audio more informative.
Gurdon’s work was in 1962. (Yes, fifty years ago.) He removed the nucleus from an egg (a frog egg, as it happened) and replaced it with the nucleus from a frog intestinal cell. From this he was able to grow a new frog. This showed that the nucleus from the intestinal cell (a specialized cell) contained all the DNA needed to grow a new frog. I think we rather take this for granted now–we now that any one of our cells contains the whole genetic cells. But Gurdon showed it at a time when it was widely thought not to be true.
His work opened the door to cloning but also to many other possibilities that are less controversial. For instances, a person suffering from failing vision because of certain retinal diseases might be cured by an injection of new retinal cells grown from her or his own genetic material. This is not, apparently, in the far realms of science fiction, but rather nearer to the present than I understood.
But, as is noted in the podcast, you still needed to use an egg in Gurdon’s process–no matter what sort of animal you might be working with. If you are thinking of practical implications of this sort of work, that’s a problem. Human eggs are hard to come by and working with them–even for medical processes other than cloning–is controversial. Indeed, there’s a lot of discussion here on the blog which I think is premised on the special nature of gametes.
This is where Yamanaka’s work comes in. In 2006 he figured out what it was that the egg did to allow the nucleus of the specialized cell to return to some undifferentiated form where all the DNA the cell carries is operational again so that the specialized cell could be used to create the whole being. And he figured out how to accomplish that without using an egg.
As I understand it, what this means is that you could start with a person’s skin cells and, building on Yamanaka’s and Gurdon’s work, grow a new retina for that person. Using skin cells is far less controversial than using eggs and you’re not even using a donor’s skin cells–they are from the person being treated.
Why does all this matter here? I ran across this story a few weeks back, but didn’t think about it as being tied into this whole line of research until today. If you can use the techniques that lead to the Nobel Prize to grow any cells, then you can use them to grow gametes–and in particular to grow eggs. This isn’t fantasy, either. As that news story makes clear, it has been done with mice.
I wrote about this development at the time I read it but I put it at the very end of a post on a much broader topic and I didn’t think that hard about what it all might mean.
First, if (and perhaps it is when?) you could do this–could reprogram a skin cell, essentially, to produce an egg cell (or for that matter, a sperm cell), then the need for third-party gamete providers would decline dramatically. After all, everyone has skin cells. The vast majority of couples trying to have kids could generate their own gametes–whether they are male/female or not.
I don’t think this would mean the end of the demand for genetic contributions from third parties. Single people who wanted to have kids would still need something from another person. And couples where one person had a heritable genetic problem might, too. But (and this leads me to the second thing) they would not need gametes. They would only need skin cells. (I assume skin cells are used because they are easy to get and other cells would do just as well.)
Here I do think we’re dealing with something way in the future, but it’s worth thinking about now. If skin cells can become gametes then we might conclude there’s nothing terrible special about gametes anymore. After all, most of us wouldn’t think hard about donating a bit of skin for medical use. But instead we might conclude that since all cells have the potential of serving as gametes, all cells should be treated as gametes–and that donating a skin cell that would be used for ART should be thought of just as we just as we think about donating gametes now.
I wonder if a person who provided a skin cell would be seen as the real parent of the child, just as some would say that a person who provides the egg or the sperm is. And whether using skin for ART would further blur the connections between sex and reproduction. There are so many questions to ask at this point. I’d best go for a walk to think it over.