Of mice misleading men?

Research into establishing the mechanisms that control normal sperm production in mice and which may later allow a better understanding of why some men are infertile, has recently been reported in the UK press, with great accolades about the promise it may bring in the treatment of male infertility. However, the jump from a future research goal to a promise that infertile men may be able to create sperm from their own stem cells, is a prodigious leap. It is not yet clear whether the source of future 'artificial sperm' for men would come from adult stem cells in the blood, bone marrow or testis, or from more emotively-charged human embryos. The latter would require therapeutic cloning, bringing with it both technical and ethical challenges.

The Newcastle researchers report mice being born following the transfer of embryos created using 'sperm' derived from sperm-forming stem cells obtained from mouse embryos. However these 'sperm' were later injected into eggs by ICSI in order to create the offspring. The embryos were not created by conventional IVF, hence it has yet to be established whether such 'sperm' have true fertilising ability and whether offspring derived from such 'sperm' can reproduce naturally. In any event, the embryos from which the stem cells were created must have been generated by normal, rather than infertile mice sperm. It is also pertinent that the reports indicate relatively short survival for the resulting offspring - which has a déja vu ring about it previously reported with animal cloning.

The fact that in men, defective sperm production is commonly associated with genetic abnormalities leads one to question whether any application of this new technology will benefit infertile couples who have this primary problem, especially knowing that boys born as a result of ICSI from men with poor quality sperm may themselves later require ICSI to father children, since nature normally precludes such sub-fertile men from reproducing.

It would be wrong to give the infertile false hope that what is appropriate for mice may also be appropriate for men.