Mice Can Now Be Cloned from Tiny Drops of Blood

Researchers in Japan have found a method to create armies of genetically-identical lab mouse clones using just a drop of blood.

For the first time ever, researchers have created viable clones of mice using just white blood cells pulled from less than 10 microliters' worth of blood, which might allow researchers to mass produce genetically identical organisms for lab testing.

Just 2.1 percent of embryos created using granulocytes and monocytes—the largest white blood cells—survived to term using the blood harvesting process, it's an important win in cloning technology because it allows researchers to create additional copies of mice that have certain infertility issues.

In lab science, that's a big deal: Mice are often genetically modified or bred to have certain diseases that model human disorders. But when one of those diseases leads to infertility, they often have to start the process over, leading to delays and increased costs in drug testing and research.

Researchers at Japan's RIKEN BioResource Center used standard somatic cell nuclear transfer (SCNT), the same method used to create Dolly the sheep and most animal clones since then. In SCNT, the nucleus of a body cell is injected into an egg cell in vitro. Most SCNT cloning is done with cumulus cells, which surround the egg cell--harvesting these cells can be difficult and invasive, with the donor animal often being put at risk. There are also a limited amount of them, so creating lots of clones is costly and difficult.

According to Atsuo Ogura, one of the authors of the study published in the Biology of Reproduction, using white blood cells offers several advantages over using cumulus cells.

"Most somatic cells can be proliferated in vitro, unlike sex cells," he said. "This makes the chance of cloning animals unlimited. Blood cells can be collected less invasively and are at the correct developmental stage of the cell cycle for cloning."

Cloned mice produced at their lab lived for up to 23 months, which is well within the normal life cycle for a lab animal. Because the process is largely only useful for creating mass quantities of an organism, the team has no plans to try cloning anything larger than a mouse. But the breakthrough could lead to faster drug development for infertility and other diseases that eventually render someone infertile.