Egg cells made with DNA from human skin fertilised in the lab

Human embryos were developed from eggs, given the DNA of adult skin cells – a feat that was previously Reached by the miceThis can once give this opportunity for gay or women with fertility Problems with children who are biologically related to both parents.

Scientists already know how to reproduce animals by cloning. This includes the replacement of the egg nucleus, which is filled with genetic material, using a body cell, such as a skin cell. But in addition to legal restrictions on human cloning, many couples want children with a mixture of both genes that require sperm and eggs, says Shoukhrat Mitalipov In Oregon University of Health and Science.

It is difficult to arrange it, because eggs and sperm chromosomes Instead of the usual two. Thus, the task is to reduce the complete set of chromosomes present in cells, such as skin cells – after choosing the healthy mixture of the original genes, as is usually the case in nature.

Girls develop all their eggs, even in the womb of the mother, where the predecessors of egg cells, which initially contain 46 chromosomes, pass the complex process of duplication, mixing and splitting to get up to 23 chromosomes.

Mitaripov wondered if he could imitate this process in his laboratory, using the advantages of natural chemical processes that prefer such a separation in mature human eggs, before and during fertilization.

After reaching this, in the mice, he and his colleagues checked the approach at the early stage of people's testing. First, they removed the cores of hundreds of eggs, which were donated by healthy women. These eggs were arrested in the exact phase in their development associated with the separation of chromosomes. Then, cores of skin cell nuclei, called fibroblasts from a healthy woman, a volunteer, were placed in these eggs. Images obtained using a microscope show chromosomes lining on spindles, cages in cells to separate chromosomes.

Then the team introduced sperm from a healthy donor for the fertilization of some eggs. This is a similar approach that is used so that children use third -person mitochondrial DNA, which is sometimes done for reduce the risk of certain genetic statesField

This injection usually triggers an egg to complete its choice of chromosome and eliminate duplicate DNA in preparation for more sperm. But in leatherThe eggs received, this process stopped, lined up with chromosomes, but never ending with the separation. Thus, the researchers tried again with a new set of fertilized eggs, this time, using electrical impulses that allow calcium to jump into the egg – imitating a natural signal launched when sperm in contact with the egg – and incubating the eggs with the help of a drug that switches from an inactive state that they usually are before fertilizer.

During a number of tests, the researchers finally reached eggs, which doubled the number of their chromosomes, eliminating additional ones. By the end of the experiment, 9 percent of the fertilized eggs became blastocysts-sha-cells, which forms about five or six days after the transformation, which is usually transmitted to the uterus during IVF. Researchers did not try to such a program and did not support blastocysts after six days.

But a mixture of genes, which made up the remaining chromosomes, turned out to be especially susceptible to defects. “I feel that this approach is currently too immature so that they can be taken into account for clinical use,” says Mitinori site At the University of Kyoto in Japan.

Hayashi At the University of Osaki in Japan, it agrees that the method is “very complex and well -organized”, but “too ineffective and risky for immediate clinical application.” Nevertheless, Hayashi says that the team made “a significant breakthrough in half of the double -man.” “New technologies will flow out of this achievement,” he says.

Mitaripov says that criticism is fair, adding that his team is working to overcome the problem with the defect. “The bottom line is that we are there halfway, but still not quite where we should be,” he says.