July 12, 2009

In vitro creation of human sperm: a case that needs more in depth scientific and ethical analysis

An incredible number of debates, especially on non-scientific media, have been raised, following the results of K. Nayernia lab research at the North East England Stem Cell Institute, Newcastle University. The scientific publication has recently appeared on the Stem Cells and Development Journal, as an online version with the title: Derivation of Human Sperm from Embryonic Stem Cells.

Many are the critics that confer to this research the perspective of a future world where male individuals will be practicly unnecessary for reproductive purposes, being able to reproduce human sperm in a lab. Other experts state this is an opportunity to study the biology of spermatozoa and suggest insights for future cures for infertility. On the other hand, others consider this kind of research against human nature itself.

What the authors of this research have done is “developed an in vitro strategy for establishing of male germline stem cells from human embryonic stem cells” which at the end are capable of forming “haploid motile sperm-like cells”.

The conclusion that the authors make is:

While full potential of the human ES derived germ cells and sperm remains to be demonstrated, this in vitro modeling of human gametogenesis provides a new approach for studying biology of human germ cells and establishment of therapeutic approaches in reproductive medicine.

I have skimmed quickly through the original scientific paper and seem to understand that:

The same lab has already published in 2006 on Dev Cell a paper titled: In vitro-differentiated embryonic stem cells give rise to male gametes that can generate offspring mice which reported both the creation of mice male gametes from embryonic stem cells and examined the successful production of an offspring (7 out of 65 embryos – which died within 5 months for some kind of abnormalities)

Only about 3.1% of cultured and treated cells were at the end haploid and only XY derived cells managed to enter meiosis in vitro and “tail like structures” could be observed only in some motile cells, whereas “XX hES cells express spermatogonia specific markers, but are not able to complete meiotic process in vitro.”

My conclusions:

I think these are very preliminary findings on the differentiation process of hESC into the germline lineage. There are no doubts that research in this field can achieve precious knowledge in understanding the biology of spermatozoa and therefore of related fertility medical issues, considering the fact that for up to 30-50% of men with reproductive problems, no cause is identified for the poor sperm characteristics.

The media buzz, as generally happens, has been oversized. I don’t see short term medical applications in this field. Safety and ethical issues need to be discussed, but the picturing of an imminent “Brave New World” scenario can be very missleading and confusing for most people.

I would really appreciate your feedback on this issue.