Scientists Produce First Animal Fetus Without Using Sperm Or Eggs

Scientists have introduced what may be the first animal created without using any sperm or egg cells. The groundbreaking study moves the scientific community a step closer to production of animals and potentially humans without the need of both male and female sex cells. 

Researchers at the Salk Institute and the University of Texas Southwestern Medical Center said they were able to produce early stages of artificial mice embryos in the lab using only stem cells. The embryos appeared like natural ones that form in the womb. 

The team used pluripotent stem cells, also known as “master cells,” from adult mice to create an early form of blastocyst. These cells gave researchers flexibility since they can be modified into any kind of tissue in the body. 

Researchers then placed the stem cells in a special culture medium. The controlled environment allowed cells to connect and turn into a ball of cells with an inner and outer layer.

The structure later appeared like a natural blastocyst, which contained similar primordial cell types found in natural blastocysts produced through natural reproduction. The lab-grown and natural embryos also had similar size and gene expression, IFL Science reported Monday

Researchers implanted the artificial embryos into a mouse’s womb. The team was surprised that it continued to develop like the early stages of a typical fetus.

The study, published in the journal Cell, suggests it is possible to create viable embryos from cultured cells. It also offers scientists a new way to produce more blastocysts to study the early stages of human development, without collecting sperm, eggs or natural embryos.

“These studies will help us to better understand the very beginnings of life; how early on in life a single cell can give rise to millions of cells and how they are assembled in space and time to give rise to a fully developed organism,” Juan Carlos Izpisua Belmonte, study author and professor in Salk’s Gene Expression Laboratory, said in a statement. “Importantly, this work avoids the use of natural embryos and is scalable.”

The researchers also hope the findings would guide development of procedures that could produce babies without using sperm and egg cells. This may offer hope to same sex couples and other people who would prefer raising their own kids without a partner.  

“Ultimately, although [it] remains science fiction at this stage, it’ll be fantastic if we can achieve the goal of generating viable embryos without sperm or eggs in the future,” Eli Adashi, who didn’t work on the new study and former dean of biomedical sciences at Brown University, said. “But there is still a long way to go since there is still a lot of unknowns during early development.”

In the current study, the mouse embryos did not turn into living, breathing mice due to structural problems. Researchers have yet to fix some problems with the approach they used before moving to human trials. 

artificial blastocyst Pictured are blastocyst-like structures (blastoids) from cultured cells immunofluorescently stained for the trophectoderm marker CDX2 (green) and the inner cell mass marker SOX2 (red). The trophoectoderm makes up the outer cells of the blastoid. Salk Institute/Waitt Advanced Biophotonics Core Facility