Mouse sperm has been created in a laboratory for the first time, and this new technique could lead to the development of new fertility treatments for human beings. The new breakthrough was reported by researchers in China, although not all scientists are convinced on the results.
If sperm of mice can be grown in labs by other researchers, the process might be adapted to the creation of human reproductive cells. However, claims of dish-grown sperm cells have been announced in the past, but the results could not be reproduced by other scientists.
In 2011, Kyoto University researchers under the direction of Mitinori Saitou announced they had successfully carried out an early stage of sperm development, creating primordial germ cells (PGCs). These cells, which are not fully-developed, are capable of turning into sperm when placed in testes, and eggs when put into contact with ovaries.
The sperm cells created in the dish were reportedly used, successfully, to fertilize egg cells of mice in the earlier study.
During the latest investigation, researchers exposed these PGCs to the testicular tissue of newborn mice and other materials. Just two weeks later, researchers report, the process formed cells similar to spermatids. Unlike fully-developed sperm, these cells are round and incapable of swimming. However, critically, chromosomes within spermatids have just one set of normally-paired genes. These cells later successfully fertilized eggs of mice, producing healthy offspring.
"The fact that the resulting cell could be injected into an egg and produce a viable animal is a stringent test," Allan Spradling from the Carnegie Institution for Science said.
However, animals born from this new technique "might still contain defects or problems that do not manifest themselves until later," Spradling cautioned.
Some critics are questioning the timetables of cell development in the study. Mice take around four weeks to convert PGCs to spermatids, a feat researchers state was accomplished in 14 days in the laboratory. The accelerated development may be the result of skipping a natural dormant period, although it is uncertain what the results of this shortcut could be in the fully-developed animal.
The artificial PCGs also appeared to develop more slowly than seen in normal development within mice in the natural world.
Discussion of the possible creation of mouse sperm under laboratory conditions was published in the journal Cell Stem Cell.
Photo: Elena Gurzhiy | Flickr
