For the first time sperm cells created with stem-cell techniques have been successfully used to fertilize eggs and produce offspring. Japanese scientists, led by Professor Mitinori Saitou from the Kyoto University, have published their findings in journal Cell. It is not the first time a study like this has been conducted. Scientists have tried to create sperm by using stem cells in earlier in vitro studies using mice and human cells, but up until now they haven’t been successful.
The Japanese team of scientists used embryonic stem cells of mice to make primordial germ cells, which are the precursors for sperm cells. They then transplanted them into the testicles of infertile mice, after which the cells produced normal-looking sperm. The mature sperm cells were used to fertilize eggs and produced healthy, fertile offspring.
These findings will encourage further research into the process of how primordial germ cells develop, something that has been difficult to investigate because these cells don’t grow in vitro. Whether future findings eventually will lead to new discoveries in human fertility remains a question. Human and mouse embryonic stem cells have different properties and any research of this kind with human stem cells will of course become an ethical issue as well.