Wednesday, February 19, 2014

Barend Vlaardingerbroek: A brave new world of pluri-potent females and redundant males


There was an exciting scientific discovery very recently: mature cells, when immersed in a dilute citric acid solution for half an hour, regress to the state of stem cells which can subsequently be cajoled into turning into specialised cells, such as a nerve cell or a liver cell. These ‘induced pluri-potent stem cells’ (iPSCs, or just iPCs) are not new in themselves, having been around for a few years, but we used to have to make them by manipulating their genetic make-up.

There’s no huge surprises here really. All cells in your body contain the same DNA, so all carry the genetic information needed to become any of the specialised cells. When you’re still a tiny ball of cells 10 days after fertilisation, you’re made of stem cells that are all alike but that start to differentiate into the various specialised types of cells a bit later.

Now that a dunk in a simple solution of a household chemical has replaced complex lab procedures involving carrier viruses, a range of possibilities as to the use of iPCs opens up. These cells may replace stem cells from discarded IVF embryos and from embryos specially created for research. They also hold enormous potential for eventual therapeutic applications, quite conceivably making organ transplants a thing of the past in a few decades. (Need a new liver? We’ll take some skin cells from you and turn them into liver cells and grow you one – and because it’s truly yours, rejection won’t be a problem.)

But an iPC can as easily be turned into a gamete-producing cell as into any other kind of cell. A skin cell from a man can be turned into an iPC and from there into a sperm-producing cell, or a skin cell from a woman into an egg-producing cell. More interestingly, though, a woman’s skin cell can be turned into a sperm-producing cell the same way, or a man’s can be turned into an egg-producing cell; we all carry the genetic blueprints for both. (No, this isn’t a flight of fancy on my part, or an attempt to usurp HG Wells or Dr Who as the king of sci-fi. It’s somewhere between being on the horizon and just around the corner. Check it out on BioEdge at http://www.bioedge.org/index.php/bioethics/bioethics_article/10842)

So two blokes, or two women, will be able to make babies by one of them producing sperm cells and the other producing egg cells, in both cases from iPCs made from cells taken from their bodies.

Those gametes are then brought together through test-tube fertilisation and hey presto, your baby, sirs or mesdames (well, in 9 months time, that is).

Will this spell the end of sex, as in ‘men and women’? After all, if women can produce sperm and men can produce eggs (albeit in a roundabout way), there seems little point in continuing to differentiate between the two. We are still talking about markedly different male gametes and female gametes, but there’s a twist: all the sperm (rather than half) produced from a female iPC will carry the X chromosome, while half the eggs produced by a male iPC will carry a Y chromosome (as opposed to none of them). An embryo will still be male or female depending on its chromosomal complement. However, we may well be talking about the end of sex in the sense of male and female persons (as opposed to gametes) being required to produce a child.

If/when this materialises, it will be a game-changer. One of the potent arguments against same-sex marriage has hitherto been that a same-sex couple are incapable of producing a child that is genetically related to them both. But if two guys or gals can create a family in the biologically purist sense of the words – i.e. by bringing about children of which both are the genetic parents – this objection has the rug pulled from under it.

For a lesbian couple, the situation seems straightforward: one provides the eggs and another the sperm via iPCs made from their cells, an embryo is transplanted into one of them, and she has a natural (well, almost) pregnancy and delivery. The child will always be a girl, for there is not a Y chromosome in sight. For a gay male couple, it’s not quite as simple. For one thing, there are both X and Y chromosomes involved now, and so the ensuing embryos may be male or female. Pre-implantation genetic diagnosis (PGD), already a well-established technology, can identify the sex of an embryo as well as genetic abnormalities, and the unwanted ones can be discarded. A quarter of those embryos will be duds anyway as they will have two Y chromosomes, which is not viable; half will be male and a quarter will be female (decisions, decisions). For another, they will have to get a woman to transplant their embryo into, i.e. a surrogate (artificial wombs still being quite some way off). So females will become independent of males in the baby-making business, albeit only for the production of daughters; but males remain dependent on females, if not for creating embryos of either sex, still for seeing them through to becoming babies.

The self-sufficiency of women in this regard has an interesting corollary: the human species can theoretically be perpetuated without men. ‘Maleness’ as a human trait can be restricted to sperm cells produced from iPCs made from women’s cells – and none of those little wrigglers contain the ‘male’ Y chromosome. With this technology, males are becoming surplus to requirements. As a bloke, I’m about to become a biological redundancy, a vestigial add-on of purely historical interest to human biology.

Alright, so I’m exaggerating just a trifle for rhetorical effect, but there is a serious message in all this. The genie is out of the bottle, and genies once released are notoriously difficult to put back in. I do think it’s time for women in particular to do some hard thinking about where all this is heading. What sort of world do you want for your granddaughters?


Barend Vlaardingerbroek lives in Lebanon and is a regular contributor to ‘Breaking Views’ on geopolitical and social issues. Feedback welcome at bv00@aub.edu.lb.

No comments: