Researchers City University Yokohama (Japan) have managed to produce sperm in the laboratory, a scientific milestone that reproductive biologists pursued since the beginning of fertility treatments in the 70's. Progress, presented in the scientific journal Nature , opens an avenue of hope for the treatment of infertility male.
For now, the research has been done in mice, so that the production of sperm in the laboratory may not yet be offered to infertile men. But the Yokohama team has proven that they have developed the technique produces functional sperm. And that the babies conceived with these sperm grow normally, without apparent health problems, which are fertile as adults.
"We need to extend our methods to other species, including humans, before applying these findings to treatment of people", said by e-mail Takehiko Ogawa, director of research. Although it is possible the exact technique has yielded sperm in the laboratory mouse is not effective in other species, Ogawa admits, "I am confident that we can do with some modification of the culture medium."
produce sperm is "one of the longest and most complex processes that take place (...) in the body," the researchers write in Nature. This is a process that goes through several stages and that in the human body requires more than a month.
To reproduce in the laboratory, Ogawa and his team removed tiny fragments of testes of mice of less than three days old. "We are enough fragments very small, less than a milligram, "said Ogawa. They used mice as young as the production of sperm precursor cells starts a few days after birth and the researchers wanted to ensure that the process could be performed in the laboratory.
placed the excised tissue culture medium at 34 degrees, the optimum temperature for growth of mouse sperm. Two technical details provided the experiment's success. One is to place the fabric so that one part was in contact with a liquid medium and another part in contact with air, liquid brought him nutrients needed for live cells and allowed to air gas exchange necessary for spermatogenesis.
The second point is that, after an initial failed attempt, a protein called KSR added to the culture medium. This protein was previously employed in stem cell research. In this case allowed us to obtain mature sperm, equipped with a mobile tail, after growing tissue in the laboratory between 27 and 45 days.
The researchers kept the experiment in progress for a few weeks to see if the fabric they used was exhausted having produced its first batch of sperm or cells continued to produce steadily as in a living being. According to the results reported in Nature, "our culture system has been able to induce and maintain spermatogenesis over two months."
At this point, needed to prove that sperm obtained with this technique could be used to fertilize eggs and they were able to father healthy offspring. Entered the decisive phase of the investigation. If babies were not born or not born healthy, we should stop using the technique to treat infertility in humans.
Investigators recovered some of the spermatids and sperm were obtained in the laboratory and they tried to fertilize eggs in vitro 58. Spermatids are the precursors of sperm cells and are also useful for in vitro fertilization because they have the same number of chromosomes, but must be handled differently. The embryos were implanted in females.
According to the results of the experiment, the birth rate was slightly higher in spermatids with sperm. In total, had four males and eight females. One the first day of life was not yet clear If these babies were healthy or whether they would be unhealthy. The researchers allowed them to grow up to reproductive age and during their growth, did not appreciate that they had no relevant health problem. To check if they were fertile, they left that mated with each other. The twelve mice conceived with sperm from laboratory proved to be fertile.
Finally, with the aim of applying this technique to infertile patients in the future, the researchers tested whether they could freeze the tissue in liquid nitrogen and then repeated the experiment successfully. This is a prerequisite for the technique could offer children who are at risk of becoming infertile because of their treatment for cancer. In these cases, it would require removal of testicular tissue before treatment, keep it in liquid nitrogen and thawed when the patient wishes to have children years later.
The experiment showed that even after freezing with liquid nitrogen, testicular tissue retains the ability to produce sperm in the laboratory. These results, the researchers conclude, "will help develop new diagnostic techniques and treatment for male infertility."
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