Twinning. Non reproductive Cloning

“Let me remind you all, however, that the issue on Agenda for today is not cloning but rather the production of identical individuals, that is, persons who share the same nuclear information. This distinction is of the utmost importance because may I remind you that cloning as a technique is not in itself banned.

The latest progress achieved since the Committee last sat in session is related to the possibility of producing human stem-cell lines and also the possibility of obtaining germ-cell lines. These cells are also undifferentiated but not necessarily embryonic cells. They can be obtained from fetuses and even from grown up adults. This new finding has brought about a number of changes with regard to cloning practices.

Last July we discussed artificial twinning and we all agreed this practice was not advisable for various reasons. Now that statement has no sense at all because in the case of a woman who produces few ovules -and therefore, few potential embryos- we can now in view of recent developments make a line of stem cells from one embryo and attempt pregnancy over and over again because we can try and clone the cell once and again so that a baby is finally produced. It may have an application on bad respondants. If only one embryo is transferred each time, the chances for pregnancy are poorer but, on the other hand, this technique will not result in the production of identical individuals because twinning does not occur, and therefore, it could be an alternative.

With regard to cloning without producing identical individuals, that is, without replicating pre-existing individuals, I believe it to be an issue that requires a deeper analysis because it offers a number of possibilities (some of which we have already discussed) that could resolve problems like the example I used before.

In the case of pregnancy disruption, as is the case of ectopic pregnancies where the embryo is lost, we could perhaps use that embryo, get a line of stem cells from it and clone the cells. In that way if the couple wishes to have “that baby” they could eventually have it through cloning. The same applies in the case of a couple where she gets pregnant at the wrong time in their lives: they want that baby but not now. Well, the pregnancy could be disrupted, a line of stem cells obtained and again, through cloning, have that baby born when the couple finds it more suitable, be it for economical or other reasons.

And the latest application that has been suggested (but this poses and added difficulty) is related to the Constitutional right of lesbian couples to procreation. In this case the procedure is simple: we clone an embryo from each woman and then we proceed to fuse them in order to produce a mixed embryo which will have the characters of both the women. We are not copying anyone but we would be producing a chimaera and that practice is forbidden by the Spanish Law on Assisted Reproduction. This is the additional difficulty I made reference to. However, chimaeras have been produced in the animal model with no major difficulty. In mice, for instance, chimaeras of up to 3 embryos have been successfully produced.

I am not going to speak about the utilisation of cloning techniques to copy pre-existing individuals because the general agreement reached by our Committee stated that this practice had no sense and was ethically speaking not advisable. (...) with E-S ( embryonic stem cells) and E-G (embryonic germ cells), the former having a potential for the production of tissues and even organs.

But let us bear in mind that in order to obtain stem cells we have firstly to produce an embryo and then destroy it. In my opinion the issue requires to be assessed in depth due to its ethical implications and perhaps Prof. Lacadena will induce the debate when he tells us about the “estatute of the embryo”.

It is obvious that in order to produce lines of stem cells not many embryos are required because a line of stem cells will in turn produce countless cells, but this should not be the core of our present discussion. The problem lies on whether the destruction of just one embryo might justify the procedure or not. However, there is a potential way of obtaining a stem-cell line without destroying an existing embryo: performing a biopsy on that embryo -as we regularly do for pre-implantational diagnostic purposes. In this way we could start a stem-cell line from a single embryonic cell although, unfortunately, this has not yet been achieved. But in any case, the embryo could still be transferred and have it develop into a baby. The embryo is not destroyed and what happens is that this embryo would have a personalised stem-cell line of its own should it ever need a transplant in its future life as a person. That would be a major achievement for, in the event of a transplant being needed, the tissue or organ would have the same genetic characters as the host and therefore, rejection risks are nonexistant.

I know it sounds complicated but surely we can all imagine a case where application might be perfectly justified, say people suffering from inherited hyperlipemia... These are people who will surely require a heart transplant at one time of their lives. Or take people with polycystic kidney...Moreover, this embryo could have its stem-cell line cryopreserved in waiting to be cultured and developed into a given tissue or organ if needed. All that could be achieved without having to produce the embryo’s identical twin to destroy it afterwards, you see?

We are talking about one embryo whose genetic characters are used to produce a new cell line. With regard to germ cells, it has not been shown for the time being that they are totipotent. We do know they can give way to new cell lines but we do not know whether they may have the same capacity and scope as stem cells. Exhaustive research on their behaviour is needed. The obvious fact is that germ cells are more easily obtained: from cordonal blood, from abortion débris but these germ-cell sources have hardly been used. It remains to be known, however, if their potential equals that of stem cells. If it does, there should be no further controversy as the source of such cells will not be subject to discussion and in addition, our problems as scientists would disappear because there would not be a need to create an embryo in order to provide the cells. All in all, these are the options that seem to stem from recent findings regarding the utilisation of certain cells in cloning practices.

GIJÓN (Spain) Meetings of 7th and 8th May 1999