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Scientists create synthetic sperm cells

Stem cells taken from the bone marrow of men can be coaxed into something that resembles an immature sperm cell, researchers working in Germany said on Friday.
/ Source: Reuters

Stem cells taken from the bone marrow of men can be coaxed into something that resembles an immature sperm cell, researchers working in Germany said on Friday.

They hope to use their findings to come up with new and better fertility treatments for both men and women.

“Our next goal is to see if we can get the spermatogonial stem cells to progress to mature sperm in the laboratory and this should take around three to five years of experiments,” Dr. Karim Nayernia, who led the study while at the University of Gottingen in Germany, said in a statement.

Nayernia, now at Newcastle University and the North East England Stem Cell Institute in Britain, had previously grown sperm cells from mouse bone marrow and used them to fertilize mouse eggs and create living baby mice.

His team worked with men who were about to get bone marrow transplants, a common treatment for cancer.

They removed some of the bone marrow, a rich source of so-called adult stem cells. These stem cells are used by the body to replenish blood, bone, muscle and other tissues.

Writing in the journal Reproduction: Gamete Biology, Nayernia and colleagues said they searched out stem cells that most closely resembled germ cells — the cells found in the testes of men and ovaries of women that eventually give rise to sperm and eggs.

“Here we show that a small population of bone marrow cells is able to transdifferentiate to male germ cell-like cells,” Nayernia’s team wrote.

“Our findings provide direct evidence that human bone marrow cells can differentiate to putative male germ cells and identify bone marrow as a potential source of male germ cells that could sustain sperm production.”

Redirecting immature cells
Stem cell science counts on being able to redirect a cell so it will create a particular tissue. The more immature a stem cell is, the more malleable it is, which is why many researchers want to work with and study stem cells taken from days-old embryos.

Unlike mature tissue, stem cells live longer, with some types being virtually immortal under the right lab conditions.

If scientists can take bone marrow cells from an infertile man and turn them into sperm, he could father a child using standard techniques such as in vitro fertilization (IVF).

Other researchers have done similar work in female mice, taking bone marrow cells and turning them into egg cells.

Dr. Malcolm Alison of Queen Mary’s School of Medicine and Dentistry in London was cautious about the findings.

“Before we get too excited about this being a new form of infertility treatment, these cells cannot as yet be made into functioning sperm, so we have no idea if they can pass ‘the acid test,’ the ability to fertilize female eggs as is achieved with donor sperm in IVF treatment,” he said in a statement.

Harry Moore of the Center for Stem Cell Biology at the University of Sheffield noted that such experiments are very difficult to replicate.

“This is a fast-moving field but we are still many years away from developing any therapies for infertility using such techniques,” Moore said.

“Unfortunately, these stem cell manipulations can lead to permanent genetic changes which would make them unsafe to use especially as a potential sperm or egg.”