Do we still need men in order to have children? Maybe not, but it is certainly easier that way
Thirty-eight years ago the world’s first in vitro fertilization baby was born; an egg was fertilized with a sperm in the laboratory. The procedure, which was revolutionary at the time, has since improved and become somewhat routine. It is estimated that more than five million babies all over the world were born thanks to IVF.
In science it is common that as soon as one challenge is overcome another one inherently pops up leading to new questions. One of the most intriguing questions is whether sperm is really required for the fertilization process or is it possible without it? If you can fertilize an egg with sperm in a laboratory and pass on both their genetic material, why not fertilize the egg with another egg and pass on the genetic material of two mothers?
Researchers from the University of Tokyo decided to study this possibility in mice. The first experiments were not successful: while the fertilized egg developed for several hours, the placenta, which is supposed to nourish it, did not. In another experiment, two sperms were inserted into an empty egg, which meant that all the genetic material came from fathers. In this case the placenta and the extraembryonic tissues developed, but not the embryo itself.
The disappointing results did not deter the researchers, but rather encouraged them to try and find out what prevents the fertilized egg from developing into an embryo, and ultimately a living fetus. Tenacity paid off and a few years later, following 460 attempts and live pups, one managed to develop and reach maturity. In 2004, an article published in Nature by a group of researchers, led by Tomohiro Kono, presented Kaguya - the first mouse offspring born from combining genetic material from two eggs, with no father. Kaguya was born healthy and developed into an adult, even producing its own offspring.
What was so difficult?
It turned out that during the creation of germ cells – the sperm and egg, certain genes undergo genetic imprinting that allows the identification of their source as either male or female. Consequently a gene becomes inactive even though the DNA sequence does not change.
Under natural conditions a paternal gene “silences” the opposite gene derived from the maternal source and the maternal gene “silences” the opposite paternal gene. This process is required for the proper development of the embryo and placenta, and therefore two sets of either female or male genomes will not develop properly.
The researchers were able to simulate the situation in nature through manipulation of the H19 and Igf2 genes, which are required for the development of the embryo and the placenta. H19 is expressed in the normal female chromosome, and Igf2 is silenced in it. In the male chromosome this situation is reversed. Because the researchers used only egg nuclei, they removed the H19 gene from one of them, leading to Igf2 expression, as would occur in natural fertilization.
Children without a father?
So when will two women be able to have a child without a man? Probably not all too soon, at least not in the same way this Japanese mouse was born. The process in humans is far more complex; we might silence or activate the wrong genes leading to genetic changes that won’t allow normal fetal development. Furthermore, a moral dilemma exists for any genetic engineering process that includes human eggs.
A solution might be in the making based on a study published in the December 2014 issue of the science journal Cell. Led by Jacob Hanna from the Weizmann Institute of Science and Azim Surani from the University of Cambridge, Scientists have shown a breakthrough in breeding by successfully extracting human stem cells that can develop into sperm and eggs. These cells can potentially transform into both mature sperm and eggs with the same genetic makeup of their donor. Perhaps, on this basis, in the future we will be able to create new therapies in the field of reproduction that will even allow women to breed with other women.
In the following video: a report from sky news on the attempts to artificially develop eggs and sperm.