British scientists have recently published their work claiming to have grown human sperm cells from an embryonic stem cell (ESC).

They took an embryo donated from an in vitro fertlization (IVF) clinic and they incubated the embryo, allowing it to grow and divide. They were able to tag the germline cells, those destined to become sperm, and separate those. They were able to coax them into meiosis, forming mature adult sperm cells.

This same group accomplished the same feat with mice in 2006. Now for the first time they have applied their technique to a human embryo.

This is an interesting advance in ESC technology. The obvious application of this specific technology would be in treating male infertility. However, using ESC would not be useful for this application. The donated embryo would be the father of any children resulting from sperm grown with this method. And of course if a man has a fertility problem, they could not have donated the sperm to make the embryo in the first place, and if they could they wouldn’t need this process.

In order for a technique like this to be a treatment for male infertility, they would have to grow the sperm from adult-derived stem cells, not ESC.

There is a separate team in Germany working on just that. Researchers from the Universities of Göttingen and Münster and the Medical School of Hannover created sperm from adult-derived stem cells obtained from bone marrow. However, these sperm were not fully motile. The researchers said at the time, in April of 2007, that they will need 5 years or so to perfect their technique.

Yet another team at Cornell University have been trying to clone sperm as a potential treatment for low sperm count. They injected a single mouse sperm into a mouse egg whose DNA had been removed, and were able to clone the sperm. However, mice resulting from the cloned sperm were abnormal. The researches conceded that their technique is still in its infancy. The researchers report:

So far, 13 mice have been born using the method, of which four survived to adulthood and produced offspring of their own. The technique is a long way from perfect, Palermo and Takeuchi admit. The researchers implanted more than 80 embryos, and of those that did survive to full term, several died soon after birth. It is not clear whether the technique would work for human sperm, in which cell division is more complex. Palermo estimates that each sperm could yield no more than eight clones, because allowing the cells to replicate more than three times could mean that the sperm DNA stops expressing male-specific genes. And the cloned sperm are spherical. Lacking the tails that normal sperm use to swim, they are suitable only for test-tube fertilization.

So at the very least we have three teams, in the UK, Germany, and the US – working on different techniques to create sperm as a potential treatment for male infertility. All groups are at an early stage in their research and saying they need about another 5 years to perfect their techniques.

As always, we will just have to wait and see. These seem like incremental advances, although important ones. Stem cell researchers are slowly improving their ability to control embryos and stem cells and make them do what they want.

However, another theme throughout all of this research is that the resulting sperm, or mice resulting from them, are not quite normal. The techniques used seem to cause damage or abnormalities in the resulting sperm. Also, the process of meiosis in humans is more complex than in mice and therefore this is likely to be more of a problem when applied to humans.  The researchers are optimistic (almost a necessity in anyone dependent upon funding) but we really don’t know how long it will take to work out the technical problems.