Katsuhiko Hayashi of Kyoto University is the lead author of a landmark paper that reports an achievement that has eluded scientists for decades.
In their most recent publication in Science magazine, Hayashi and his colleagues made mouse eggs from induced pluripotent stem cells in a culture dish, and then fertilized them with mouse sperm to create healthy, fertile mice.
This work is a continuation of reports published by the same core group of scientists at Kyoto University who made healthy mouse sperm in the lab from induced pluripotent stem cells and embryonic stem cells (K. Hayashi, H. Ohta, K. Kurimoto, S. Aramaki, M. Saitou, Cell 146, 519 (2011)). If this work can be applied to humans, it will revolutionize fertility treatments.
During the development of mammals, primordial germ cells (PGCs) become one of two cell types depending on the sex of the embryo. For example, if the embryo has an X and a Y chromosome, the PGCs differentiate into spermatozoa, but if the embryo is female and has two X chromosomes, they form oocytes. Sperm and eggs combine during sexual reproduction to form a single-celled embryo known as a zygote, and zygotes have the full developmental potential to grow into the adult animal.
In this paper, Hayashi used mouse embryonic stem cells and surrounded them with cells from the embryonic ovary. This creates a kind of “reconstituted ovary” which is then transplanted into a living mouse to develop. After being cultured in a mouse body for four weeks and four days, this culture system induced the embryonic stem cells to form PCG-like cells that went through all the stages of oocyte development. Fertilization of these oocytes produced by this reconstituted ovary system produced fertile, viable offspring. They also repeated this experiment with induced pluripotent stem cells and they successfully converted these stem cells into PGC-like cells that also underwent successful fertilization.
This experiment has already provided lots of fodder for bioethics bloggers all over the globe. Wesley Smith at his Human Exceptionalism blog at National Review has written the following:
“That mind-exploding point aside, the primary purpose for using this technique in humans would probably be to create mass egg quantities for use in cloning experiments. Each cloning attempt (using SCNT, the technique resulting in Dolly) requires a human egg. At present, human cloning has not been reported–primarily because of the “egg dearth” that inhibits researchers from the kind of repeated trial and error experiments necessary to perfect technique in humans.
Scientists probably need thousands of eggs to figure out human cloning, but they are in extremely short supply because the only sources currently are women of child-bearing age. Efforts are ongoing to remedy that problem–such as using eggs taken from the ovaries of aborted female fetuses or removed from women surgically. If the iPSC approach can be made to work in humans, there would be an infinite supply of eggs, meaning that human cloning would just be a matter of time.”
Smith is right on this one. Human cloning is being held back by its ridiculously low efficiency and the paucity of eggs for such research. Human cloning would be done for research purposes, but its main purpose would be to replace people who have died, or to make embryos or babies to are organ donors for sick adults.
A few years ago, there was a Michael Bay movie entitled “The Island” with Scarlett Johansson and Ewan McGregor. In this movie, McGregor and Johansson are part of a society that lives in a highly controlled environment in which they are told what to wear, what to eat, when to sleep, where to go, and what to do. The only hope they have is to win a supposed lottery that lets them go to “The Island.” Winners are announced on a daily basis, and when they are announced, they are never seen again. McGregor serendipitously discovers that they lottery winners do not go to the Island, but rather go to a surgical room where they are put to sleep and robbed of their vital organs.
McGregor returns to inform Johanssonof the elaborate ruse under which they are living just as Johansson is announced to be the recent winner of the lottery. They escape from the compound and are relentlessly pursued be those company that runs the facility where McGregor and Johansson were housed.
It turns out that McGregor and Johansson are clones of wealthy people who can afford to have a replica of themselves as “insurance policies.” The clones are known as “products” by the scientists who produce them, and the medical staff hardly thinks twice about dispatching each clone for their organs or do deliver a baby for the super-rich who do not want to go through the pain of childbirth.
In one scene, the CEO of the company that produces the clones makes a sales pitch to potential customers in which he speaks of an entity called an “agnate” that contains organs and stem cells for treatments, but has no consciousness or human structure. These patrons think that they are buying the rights to a blog that has their organs, when in fact, they are buying a clone that is a human person that was made by a manufacturing process and is genetically identical to them.
While I do not know the bioethical views of Michael Bay, his movie makes a remarkably telling case against human cloning. Cloning produces a human embryo. While it might have some developmental abnormalities, it is a human person. Farming cloned embryos for tissues is exactly the same as farming cloning human adults for body parts. The only differences are the size, age, and developmental stage of the human persons. Neither size, nor age, nor stage of development are adequate criteria for disqualifying someone from the human race. If this was the case, then six graders would be more human than fifth graders, tall people would be more human than short people, and two-year olds would be more human than one-year olds all of which are patently absurd.
If you are going to argue that the developmental abnormalities of cloned embryos should disqualify them, then you are saying that the less well endowed among us do not have the right to live, which puts you in the same ethical category as Adolph Hitler. People are people, and their identity is the same regardless of their deformities.
This research should give us pause. Human cloning should be banned regardless of whether it is called therapeutic or reproductive cloning. Both manipulate human beings and that is wrong.