Mice carry cells ... human brain!

US scientists have just created mice that carry a small amount of human brain cells. The goal is to create real models for studying neurological disorders, such as Parkinson's disease.

The team, led by Fred Gage of the Salk Institute, created the mice by injecting about 100,000 human embryonic stem cells into the brain of every 14-day-old mouse embryo. As a result, the mice were born with about 0.1% of human cells in their heads. However, such stem cell injections do not reconstruct the rat brain nor can it "humanize" the rodent.

Researchers believe that mixing human cells with animals is important in ensuring that new experimental drugs and tissue replacement are safe for humans. This is the only way to promote tissue replacement therapy with stem cells. The cause is too risky to test on humans and the scientific community knows too little about stem cells.

Some experts have conducted similar tests for rabbits and chicken eggs. Meanwhile, scientists at the University of California-Irvine have reported making mice able to move after injecting them with human neurons. For years, doctors have grafted pig heart valves into people's hearts. The injection of human cells into experimental animals took place much earlier.

However, injecting human cells into the animal's brain is of particular interest because many people fear the scary scenario: the human brain may be in the animal's head. After all, 97.5% of the mouse genome is identical to the human gene. David Magnus, director of the Stanford Medical Ethics Center, said: "I don't think this research is close to that prospect."

Minh Son