Stem Cells: Of Mice and Men

Scientists from the University of Tübingen has succeeded in harvesting stem cells from the testes of adult men. In lab tests with mice, the cells behaved just as embryonic stem cells do, including the ability to develop into many different kinds of cells: bone, muscle or nerve. The possibilities are exciting for potentially curing such diseases as Parkinson's disease.
You can't see it with the naked eye, but in this test tube, human tissue is being grown. Thomas Skutella and other German researchers are growing a blood vessel, adding stem cells in layers. It's fundamental research for creating tailor-made replacement tissue, which could one day help patients with diabetes or Parkinson's Disease.


Prof. Thomas Skutella, Uni Tübingen: "We hope at some point to be able to regenerate or replace more complex organs like the liver or even an entire heart muscle."



With the help of his team, Skutella has now come a step closer to realizing this dream. The scientists have derived so-called human adult germline stem cells, or GSCs, from the testes of adult males. Could they be the alternative to human embryonic stem cells?


Searching for embryonic stem like all-rounders


The embryonic stem cells are all-rounders. They can reproduce endlessly and turn into any kind of tissue: nerve, bone, muscle or blood. But generating them requires that the embryos be destroyed. So the research in Germany is strictly regulated.


So-called adult stem cells are no problem, those derived from skin for example. But by their nature, they can't turn into other kinds of cells because they come from already developed tissue. Researchers are now working to make these adult stem cells become more than just their own type.


For men only?


The human adult germline stem cells discovered by the Tübingen researchers seem to represent a third type. They are all-rounders, just like embryonic stem cells, and they survive longer than adult stem cells do. But stem cells derived from testes - does this limit their potential application to men only?


Prof. Thomas Skutella, Uni Tübingen: "Here we're talking about stem cells that later develop into sperm cells. Women have them too, stem cells which in their case develop into egg cells. We can in turn take those cells from adult women."


The researchers are testing their new human adult germline stem cells on laboratory mice, examining to what extent they can turn into other cells. They inject the mice with the GSCs. The injected cells form a lump. And there the researchers find every kind of tissue. Skin, nerve, cartilage and bone cells.


Prof. Thomas Skutella, Uni Tübingen: "We didn't do much manipulating. We added things to the cell culture within the limits allowed in clinical research. So we would be very close to the clinical testing stage for these cells."


It will still be some time before the technology can be tested on humans. In the next three years, the Tübingen researchers want to research the properties of GSCs in more detail. And they want to try producing cells for specific purposes, like making insulin. Today's scientific groundwork could lead to exciting therapeutic breakthroughs in the future.


Cornelia Borrmann