A team of scientists in China have made history by growing fully functional sperms from stem cells. This is considered as one of the major scientific development that could help in treating the infertility in humans in the near future.
If you look at the numbers, one in every six couples (i.e. around 16%) suffers from infertility and cannot produce their off springs which might be due to a disease, an injury, or age-related conditions. Out of the total infertile cases, around one-third is due to male who are unable to produce viable sex cells (a process known as Gametogenesis). The main cause of fertility is due to the failure of precursor germ cells present in the testes to undergo meiosis, a type of cell division. To create functional sperms in vitro has been the main objective of the reproductive medicine field.
Research Findings: Sperms From Stem Cells
Researchers have claimed that they have succeeded in creating fully functioning sperms from stem cells (mouse embryonic stem cells) in the laboratory. The recapitulation of meiosis, a process unique to germ cells, was the major obstacle for producing functional gametes in vitro.
Jiahao Sha of Nanjing Medical University has teamed up with co-senior study authors Xiao Yang Zhao and Qi Zhou of the Chinese Academy of Sciences’ Institute of Zoology to develop a method that repeat meiosis and produces fully functional sperms from stem cells. They have used embryonic stem cells (ESCs) of young mice aged between two and eight years, to create functional primordial germ cells which can be passed on to the next generation.
The researchers have first exposed the mouse embryonic stem cells (ESCs) to a chemical cocktail, in order to turn them into primordial germ cells. They have created a natural tissue environment by posing these germ cells to testosterone, sex hormones, where they have undergone complete meiosis process. The researchers have then injected the newly formed sperm like cells into mouse egg cells to form embryos. When these embryos were transferred into female mice, it has been found that embryos developed normally and gave rise to a fertile offspring.
Jiahao Sha and his team has described their work in the U.S. journal Cell Stem Cell. They have explained how they carried out the complete meiosis from embryonic stem cell derived germ cells in the lab.
In their report, they have explained the complete in vitro meiosis from murine ESC-derived primordial germ cells-like cells (PGCLCs) resulting in the formation of male spermatid-like cells (SLCs) which are capable of producing viable fertile offspring via intracytoplasmic sperm injection (ICSI).
According to the researchers, while the cells formed are germ lines cells, i.e. similar to those from embryonic stem cells, but there were certain key functions which were behaving differently compared to normal embryonic stem cells. This indicates that more deep research is needed to ensure that the procedure would be safe and effective. To successfully use this technique for creating a baby who will grow into a healthy adult, it is necessary for germs cells to go through with all the different processes which they are supposed to, for proper functioning of the cells. One of this process is gene regulation which must occur, for sperms to work properly.
Sha said that the current methods available for artificial insemination do not work for many couples. He said that they have established a robust approach to repeat the formation of sperms from stem cells which promises to treat the problem of male fertility. According to co-author Xiao Yang Zhao, it is too early to discuss the clinical use of the technique and they need to study the possible risks involved in this process before using it on humans, as there are a lot of differences between mice and humans.
Stem cells is one of the most promising area of the bio-medical research and have the potential to improve the treatment for most of the complex diseases. Researchers are hoping that this technique would substantially improve the success rates of the artificial insemination or in vitro fertilisation techniques and will prove to be a landmark in the stem-cell field.