Cells from testicles used to make stem cells

Scientists have discovered a novel way of identifying the tiny subset of adult stem cells that exist in testes and of reprogramming them to develop into other bodily tissues. If this technique can be replicated in humans it could provide a plentiful and more ethically acceptable source of stem cells for treating men with diseases such as Parkinson's, Alzheimer's, stroke, diabetes and even certain cancers, according to research published in the journal Nature last week.

The ongoing ethical debate over stem cell research hinges on the fact that embryos are destroyed in the process of harvesting stem cells - highly specialised cells prized for their ability to develop into any one of the body's different cell types. This controversy has driven the hunt for adult stem cells high up on the global research agenda, with previous attempts at finding alternative sources in skin cells, bone marrow, umbilical cord blood, and other tissues.

Study leader Dr Shahin Rafi, who has spent over a decade researching a potential source of stem cells in testes at the Howard Hughes Medical Institute, believes his discovery 'could someday mean a readily available source of stem cells that gets around the ethical issues linked to embryonic stem cells.'

Previously it has been problematic for scientists to identify and isolate the scarce numbers of stem cells that exist in adults, which are often less flexible than embryonic stem cells in their ability to develop into different types of cells. However, following successful trials in mice, Rafi and colleagues from the Weill Cornell Medical College are confident that they have found a potential solution. 'It appears that these unique specialised spermatogonial cells could be an easily obtained and manipulated source of stem cells with exactly the same capability to form new tissues that we see in embryonic stem cells', said Dr Rafi.

The researchers identified a genetic marker- gpr125 - which is unique to the 0.01 per cent of stem cells found in testes, allowing them to harvest the cells and then propagate them in the lab before reprogramming them into stem cells. In mice, the researchers found the cells could be made to become part of the living blood vessels and in the lab, they could be transformed into brain, heart and muscle cells.

The next step will be to replicate these findings in humans, says Dr Rafi, highlighting that 'some hurdles remain', such as being able to identify a similar 'switch' in humans which can reprogram gpr125 expressing cells in the testes into adult stem cells. 'We believe this to be an easily obtainable goal in the near future', he said.