Can Babies Be Created Without Female Eggs?

[Greg Bernhardt]

Baby mice created from sperm, without an egg
http://www.cnn.com/2016/09/14/europe/mice-sperm-reproduction-eggs/index.html

Scientists at Bath University in the United Kingdom say they have successfully used sperm to create healthy baby mice by injecting the sperm cells directly into embryos.

Speaking to CNN, Perry said while at this stage the only way to create an embryo was using an egg, it could be possible in the future to create embryos without the original female cell.

How exactly do you get the embryo in the first place without an egg? Furthermore how do you get an embryo without already injecting it with sperm? This news clip is really confusing. I'm not sure what the actual big development is here.

 

[Ygggdrasil]

Here's a citation to the paper they're discussing:
Suziki et al. 2016. Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes. Nat. Commun. 7:12676. doi:10.1038/ncomms12676

Abstract:

Sperm are highly differentiated and the activities that reprogram them for embryonic development during fertilization have historically been considered unique to the oocyte. We here challenge this view and demonstrate that mouse embryos in the mitotic cell cycle can also directly reprogram sperm for full-term development. Developmentally incompetent haploid embryos (parthenogenotes) injected with sperm developed to produce healthy offspring at up to 24% of control rates, depending when in the embryonic cell cycle injection took place. This implies that most of the first embryonic cell cycle can be bypassed in sperm genome reprogramming for full development. Remodelling of histones and genomic 5′-methylcytosine and 5′-hydroxymethylcytosine following embryo injection were distinct from remodelling in fertilization and the resulting 2-cell embryos consistently possessed abnormal transcriptomes. These studies demonstrate plasticity in the reprogramming of terminally differentiated sperm nuclei and suggest that different epigenetic pathways or kinetics can establish totipotency.

I'm not an expert in the area, but I think one can stimulate unfertilized eggs to develop into non-viable embryos through a process called parthenogenesis (in some animals, parthenogenesis can result in viable embryos, but this is not the case for humans). From a quick skim of the article, the article seems to be addressing the scientific question of how the genetic material of sperm gets "reprogrammed" during fertilizaiton (for some background on the concept of cell reprogramming, see this recent thread on PF). The article itself does not seem to suggest any immediate clinical applications.

In terms of reproductive technologies, I think a game-changing technology would be the ability to reprogram differentiated cells into egg cells. Currently, we have the ability to reprogram differentiated cells (like skin cells) into cells that resemble stem cells (called induced pleuripotent stem cells or iPSCs). If we could then figure out the conditions to get those iPSCs to differentiate into viable oocytes, we would be able to avoid performing surgery in order to obtain eggs for reproductive procedures like in vitro fertilization (instead, doctors would only need to take a skin biopsy). This technology would also make https://www.physicsforums.com/insights/dont-fear-https://www.physicsforums.com/insights/dont-fear-crispr-new-gene-editing-technologies-wont-lead-designer-babies/-new-gene-editing-technologies-wont-lead-designer-babies/ easier, as researchers could start with a large pool of oocyte precursor cells, perform gene editing, then screen for cells that contain the desired gene edits and not any unwanted changes to the genome.

 

[BillTre]

Several years ago zebrafish researchers showed they were able to fertilize an egg by injecting either a sperm cell nucleus or a sperm cell body (with out the tail which would get in the way) and get fairly normal embryos.
Also in zebrafish, it is possible to routinely make haploid embryos which can develop for a few days before dying. They only have genetics from the female parent and are used in research to reveal recessive mutations because there is only one copy of each gene present. This is done by "fertilizing" eggs with sperm that has been irradiated with UV light which busts up the DNA enough to make it inoperable for genetics. The sperm cell is metabolically alive but genetically empty. It does however get the cellular events of development started.
This sounds like they injected a sperm cell into a cell derived from a embryo, made in some way similar to this, or perhaps injected cells within an embryo.
That "fertilized" cell(s) would then have to be grown up to make an embryo. Its unlikely that an embryo of a thousand cells or more would all get "fertilized" at once. On the other hand, as the haploid cells around a few "fertilized" cells die or stop growing, the diploid cells derived might multiple and perhaps take over the embryo resulting in a fully diploid embryo after a few days. That sounds kind of sloppy to me but it may work. It would be kind of like the cells of the monster in The Thing (1982, Carpenter version) taking over the bodies of other creatures.

 

[256bits]

Here's another write up.
http://www.msn.com/en-ca/news/world/scientists-have-found-a-new-way-to-create-mice/ar-AAiR6Qh?OCID=ansmsnnews11

 

[256bits]

And another,
http://www.the-scientist.com/?artic...udy--Mitotic-Cells-Can-Reprogram-Mouse-Sperm/

The team “shows that eggs that have already begun embryonic development, and are about to divide from the one-cell to two-cell stage, still retain the ability to ‘remodel’ sperm DNA,” Hugh Clarke, a developmental biologist at McGill University in Montreal who was not involved in the work, told The Scientist in an email. “So this ability is not restricted to eggs at the time of fertilization.”

Already some disagreement with the researchers conclusion.

In their paper, the researchers wrote that the work “calls into question the argument that parthenogenotes do not have the potential for full-term development.”

Clarke disputes that. “Here, they added a paternal genome to the parthenogenetic embryos and only then obtained development to term. So it does not at all challenge the dogma that both a maternal and a paternal genome are needed for embryonic development in mammals,” he said.

 

[BillTre]

Here is a new story from Science (Mag) that follows a game of telephone through different media out to newspapers.
The message diverges as it is propagated along.