Scientists grow sperm from stem cells

Scientists have turned stem cells from an embryo into sperm that are capable of producing offspring, it was announced yesterday.

The advance in reproductive science raises new opportunities to treat male infertility and the possibility that women could make sperm.

The professor behind the research believes that, when safe, the advance could help men with certain types of infertility to become fertile, to remain fertile for longer and, controversially, could even one day enable a lesbian couple to have children that, at the genetic level, are truly their own.

Professor Karim Nayernia, whose work with stem cells resulted in the birth of seven mice The experiment used embryo cells to produce seven baby mice, six of which lived to adulthood, though the survivors suffered problems of the kind also seen with cloning. A team led by Prof Karim Nayernia isolated embryonic stem cells from a blastocyst, an embryo only a few days old that consists of a cluster of cells. These cells were grown in the laboratory and screened to sort out the spermatogonial stem cells, which were genetically marked, grown and then injected into female mouse eggs and grown into early-stage embryos.

After transplant into female mice, seven babies resulted. Six developed into adult mice, though the animals were either too small or too large, and they died prematurely.

The advance, reported yesterday in the journal Developmental Cell, helps scientists understand more about how animals produce sperm, creates more opportunities to carry out genetic alteration of animals, and shows that cells may one day be coaxed in the laboratory to make sperm to treat infertility. In the long term, cloning methods could be used to turn a skin cell from a man into sperm and Prof Nayernia said it was even possible that it could be achieved using a cell from a woman.

Prof Nayernia, Professor of Stem Cell Biology at Newcastle University, said: "This research is particularly important in helping us to understand more about spermatogenesis, the biological process in which sperm is produced. We must know this if we are to get to the root of infertility.

"If we know more about how spermatogonial stem cells turn into sperm cells, this knowledge could be translated into treatments for men whose sperm is dysfunctional, although this is several years down the line.

"For example, we could isolate a patient's spermatogonial cells, encourage them in the laboratory into becoming functional sperm and transplant them back into the patient."

Harry Moore, Professor of Reproductive Biology, University of Sheffield, said: "This latest finding is exciting, as it is the first indication that germ cells [immature sperm cells] produced in this way have the full potential to create an individual. This opens up many important possibilities for research related to genetics, cancer and cell reprogramming."

It could shed light on how abnormal development of germ cells in men may lead to testicular cancer and infertility but he added: "The latest findings also highlight that these processes in the test tube are far from perfect as the mice that were born by this process were abnormal.

"We therefore have to be very cautious about using such techniques in therapies to treat men or women who are infertile due to a lack of germ stem cells until all safety aspects are resolved. This may take many years."

(Telegraph News)