Chinese scientists report they have created mouse sperm in a laboratory and used it to fertilize eggs, resulting in the birth of healthy mice.
The findings were released in the peer-reviewed Cell Stem Cell journal on Feb. 25, and they could reportedly have major implications for the treatment of infertility.
“If proven to be safe and effective in humans, our platform could potentially generate fully functional sperm for artificial insemination or in-vitro fertilization techniques,” Dr. Jiahao Sha, who led the study, said, according to Mirror.co.uk.
Biologists have been working on the creation of sperm for some time. In 2011, researchers at Kyoto University in Japan achieved the first stage of sperm development when they produced cells resembling primordial germ cells (PGCs), Scientific American reports. They implanted the PGCs into a mouse, and the cells later developed into sperm.
The Chinese team claims they have now performed this stage of development in a dish, causing PGCs to turn into spermatids. These are not fully matured sperm, but they have just one set of chromosomes, meaning they can fertilize an egg.
“Because currently available treatments do not work for many couples, we hope that our approach could substantially improve success rates for male infertility,” Sha said, Mirror.co.uk notes.
Several scientists have expressed doubts about the results but welcomed the potential step forward.
“You have to be very cautious about the implications of this paper,” Mitinori Saitou, who led the 2011 research which created PGCs, said, according to Scientific American.
“The fact that the resulting cell could be injected into an egg and produce a viable animal is a stringent test,” reproductive biologist Alan Spradling of the Carnegie Institute of Science said. “[But the mice that were produced] might still contain defects or problems that do not manifest themselves until later.”
Scientists also questioned how the Chinese team's development of PGCs into spermatids occurred in just 14 days. In a real mouse, this development takes more than four weeks.
“Our method fully complies with the gold standards recently proposed by a consensus panel of reproductive biologists, so we think that it holds tremendous promise for treating male infertility,” Sha said, according to Mirror.co.uk.
Similar tests using human cells are in their early stages, with researchers attempting to produce human PGCs.
“In spite of these encouraging results, we are still some way from immediately applying this technique as a potential cure for human male infertility,” Allan Macey, a professor of andrology, said.