Mice created from two fathers grow into adults for first time, study reports

New Delhi, Jan 28 (PTI) Researchers have created mice from two fathers, with some of them surviving till adulthood for the first time, a development that could advance the research of stem cell research and regenerative medicine.

The study, published in the journal Cell Stem Cell, was conducted by researchers at the Chinese Academy of Sciences, who detailed how described how they targeted genes to overcome "previously insurmountable challenges" in same-sex reproduction in mammals.

Previous studies have documented scientists' attempts to create mice from a pair of male mice, using stem cells. Found in organs and tissues throughout the body, stem cells can develop into different types and are important for growth and maintenance.

However, the embryos so far created, developed only to a certain point and then stopped growing, the study's authors said.

"This work will help to address a number of limitations in stem cell and regenerative medicine research," lead researcher Wei Li of the Chinese Academy of Sciences, said.

The authors explained that in earlier attempts, stem cells from male mice were used to derive an 'oocyte' -- a cell in an ovary which can then form ovum, or egg cell.

The oocytes were then fertilised with a sperm from another male mouse to form embryos.

However, when the chromosomes -- which are known to divide for creating oocytes and sperm -- came from the same sex, imprinting disorders arose, leading to severe developmental defects in the embryos, the researchers said.

Imprinted genes are those that are expressed differently, depending on whether they came from the mother or father. Disruptions to imprinting can cause genetic disorders.

In this study, the researchers targeted imprinting genes, individually modifying 20 critical ones using varied techniques, including gene deletion.

They found that the gene edits allowed the creation of bi-paternal animals that lived longer and that the stem cells so formed had a "more stable pluripotency". Pluripotent stem cells are those that can become any cell or tissue in the body.

"These findings provide strong evidence that imprinting abnormalities are the main barrier to mammalian unisexual reproduction," corresponding author Guan-Zheng Luo of Sun Yat-sen University in Guangzhou, China, said.

This approach can significantly improve the developmental outcomes of embryonic stem cells and cloned animals, paving a promising path for the advancement of regenerative medicine, Guan-Zheng added.

Acknowledging the study's limitations, the authors said only 11.8 per cent of the viable embryos were capable of growing in the womb till the time they were born, and not all pups (baby mice) that were born lived to adulthood, due to developmental defects.

The researchers said they'd now like to attempt the same technique in larger animals, including monkeys.

"Using bipaternal mouse embryos, which exhibit severe imprinting defects and are typically non-viable, we introduced frameshift mutations, gene deletions, and regulatory edits at 20 key imprinted loci, ultimately achieving the development of fully adult animals, albeit with a relatively low survival rate," the authors wrote. PTI KRS OZ OZ