Australasian Science: Australia's authority on science since 1938

The Mouse with Two Fathers


US scientists have produced mice from two fathers using stem cell technology.

The researchers used a type of cell from a male mouse known as a fibroblast to produce stem cells. A portion of these stem cells spontaneously lost their Y chromosome so they only contained an X chromosome. These stem cells were then injected into embryos from donor female mice and were transplanted into surrogate mothers. The offspring of these mice were then mated with normal male mice. Some of the offspring were male and female mice that had genetic contributions from two fathers. The research was published in Biology of Reproduction.

“The study is provocative in the way a good fictitious novel causes us to think about what defines our nature. However, as far as the practical translation of this work is concerned, there are significant barriers to its use in humans.

“Effectively what occurred is that adult cells from one male mouse were manipulated and then implanted in a female mouse. The mother mouse then gave birth to offspring that were derived from the first father. These offspring were then mated with the next father. The mice born were genetically derived from two male mice. However, the process works in mice under careful controlled procedures for selecting appropriate offspring and then mating these with the second father.

“The work answers interesting scientific questions about whether adult-derived cells can be transformed to true stem cells. However, in terms of making humans with two dads, the procedure is not viable. For now at least, the idea that we can have two fathers is a challenge to our thinking but not to reality.”
Dr Bryce Vissel, Garvan Institute of Medical Research

“Whilst the findings in this paper are intriguing, whether such an approach could ever be applied to human reproduction is highly unlikely. The mice were not born simply from two fathers. Rather, they were created by a complex process dependent on access to foetal tissue, the creation of stem cells, additional embryos, surrogate mothers and natural mating.

“Leaving aside the practicalities of applying such a convoluted process to create a human baby, there are significant safety, ethical and legal considerations that prevent its application. The real value of pluripotent stem cell research lies with increasing our understanding of normal development and disease.”
Dr Megan Munsie, Senior Manager, Research and Government, Australian Stem Cell Centre

“With the emergence of induced pluripotent stem cell technology, it is now possible to understand many complex biological processes like reproduction rapidly which otherwise is not possible or feasible because of ethical constrains. Previously it has been demonstrated in many laboratories, including our group, that the embryonic stem cells derived from embryos, and induced pluripotent stem cells produced from adult cells from the body of males or females, have the equal potentials to produce male and female germ cells in the Petri dish under appropriate culture conditions (i.e. male stem cells can produce female germ cells and vice versa).

“This current research may seem very tantalising for same-sex couples but you still need females to incubate the embryos for live birth and also the XO stem cell clones are generally not viable unlike in mice. Some of the projections in this paper on humans are a bit far-fetched as yet.

“Such experiments are not possible in humans because of ethical issues and lack of legislation. However, the existing cloning legislation in Australia is up for review now and we the scientists are keen that human–animal hybrid research should be allowed to test some of the mechanisms as above in humans, and that may have long-term consequences in human infertility and regenerative medicine.”
A/Prof Kuldip Sidhu, Director of the Stem Cell Lab and Chair of Stem Cell Biology, University of New South Wales

“This is an interesting and novel use of pluripotent stem cell technology that may have application for the preservation of endangered animal species. In its current form this type of research is not likely applicable to humans. To carry out these experiments using human cells, donated human blastocysts and surrogate mothers would be unethical (as the effects on the resulting human offspring would be highly unpredictable) and probably illegal.”

Dr Andrew Laslett, Research Team Leader at CSIRO Materials Science and Engineering. Dr Andrew Laslett currently directs an independent research team working with human embryonic stem cells and human induced pluripotent stem cells to better understand their basic biology.

“The report of mouse pups of a different gender being produced from the iPS cells of their parent is a natural progression from earlier reports of live mouse pups being born from iPS cells of adult mice. However, when those reports came out two or three years ago it was widely believed that it would take years to produce pups of the same sex, if that was ever possible. This shows the rapid progress in this area of science.

“The new research may lead same-sex couples, both male and female, to hope that same-sex couples may one day be able to have a child who is genetically related to both of them. However, even if such a technique was possible in humans, it could not lawfully occur in Australia under the current law. Federal and state legislation prohibits the combination of DNA from more than two people in forming an embryo, and implanting an embryo formed for research into a woman.”
Prof Loane Skene, Professor of Law, University of Melbourne; former Deputy Chair of the Lockhart Committee on human cloning and embryo research.

Source: AusSMC