Bone Marrow Stem Cells "Germinate" into Sperm Cells

By Dr. Matt Wilkinson, DrugResearcher.com, April 14, 2007

Potentially leading to a revolution in fertility therapy, certain human bone marrow cells have shown the ability to differentiate into sperm stem cells according to a new study.

Researchers managed to encourage mesenchymal stem cells (MSCs) to differentiate into reproductive cells, known as germ cells. The study was led by Professor Karim Nayernia of Newcastle University in the UK.

The cells could be used to produce eggs and sperm for patients suffering from infertility since they are a new source of female and male germ cells.

But there is a challenge when it comes to encouraging the cells to mature fully say researchers.

"In the long term the aim would be to isolate these stem cells from a patient and then bring them back to the same patient after differentiation to try to treat infertility," said Nayernia.

He explained that the research could potentially restore patient’s fertility by replacing germ cells in the testes, and that many types of chemotherapy destroy these germ cells.

Several markers that are expressed in male germ cells only were exhibited during immunohistochemical analysis conducted by the researchers.

Spermatagonila cells can be created from mouse bone marrow, and the current research builds upon these previous findings. Before, the mouse cells were able to undergo cell division, but did not develop any further into the latter stages of the formation of sperm cells. The research, built upon previous research by the group that showed that mouse bone marrow could be used to create spermatagonial cells. While these cells were observed to undergo cell division, the next stage in the formation of sperm cells, they did not develop any further. The journal Reproduction: Gamete Biology has published the findings.

"Our next goal is to see if we can get the spermatagonial stem cells to progress to mature sperm in the laboratory and this should take around three to five years of experiments," he said.

In regards to the potential of embryonic stem cells to provide a cure for infertility, Nayernia explained it would be impossible. The adult stem cells, or bone marrow stem cells in this case, have far greater potential for being a cure since there is no way of collecting embryonic stem cells from infertile subjects.

"At the moment we have sperm stem cells and we have some evidence that they can differentiate all the way into sperm cells," said Nayernia.

Along with multipotent adult progenitor stem cells, hematopoietic stem cells, and endothelial stem cells; MSC’s are found in the bone marrow as well.

The MSC’s must be separated from the other types of cells after the bone marrow stem cells have been isolated. But Nayernia says this is now a routine process.

In order to encourage them to differentiate into germ cells, the isolated cells were cultured in a medium very similar to that found in the testes.

Nayernia also talked about Leydig cells that secrete various hormones and sertoli cells which 'nurse' developing sperm. He said that an American research team used bone marrow stem cells to created those types as well.

There are men who already have healthy germ cells, but since they lack these supporting cells, they still cannot produce sperm cells. The American approach could lead to a fertility cure for those men.

Nayernia even added that extinct species could some day be re-created by combining the two approaches. They could take bone marrow cells for extinct species such as the frozen woolly mammoth and create actual living animals once again just like the movie Jurassic Park.