The synthetic sperm

Stem cells taken from the bone marrow of men can be coaxed into something that resembles an immature sperm cell.

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

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.

“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.

embryonic stem cells used in research most often come from embryos left over after in vitro fertilization procedures.

Step One: An egg is fertilized by a sperm in a lab dish

Step Two: The fertilized egg begins to divide and develop into an embryo. About five days later, the embryo becomes a blastocyst -- a hollow ball of about 100 cells. The inner cells are the embryonic stem cells.

Step Three: Stem cells are removed from the blastocyst and cultured in the laboratory where they theoretically can multiply indefinitely.

Step Four: By adding and removing certain proteins, scientists can coax the cells to develop into new heart, bone, nerve or other cells.

Source: www.msnbc.msn.com