European researchers made a huge step in stem cell research by converting cells from human testicular tissue into stem cells that were further able to grow into muscle, nerve cells, and other kinds of tissue. The new study was published online Oct. 8 in the journal Nature.

Stem cell research has been a subject of controversy from the very beginning as it uses human embryos in order to create stem cells. Critics of embryonic research include Catholic Church, US President George W. Bush and German lawmakers. Bush even banned funding of research that uses newly destroyed embryos.

However, there are many scientists supporting this field, saying that the fast-multiplying cells obtained in a human embryo could result in medical advances that save lives. The research has been considered to hold the key to potential treatments, even cures, for such conditions as heart failure, diabetes, and Alzheimer's and Parkinson's disease because embryonic stem cells have the potential to develop into any other cell in the body.

The new study was conducted by Thomas Skutella, director of the Center for Regenerative Biology and Medicine, in Tuebingen, Germany, and his colleagues. They used testicular tissue from 22 men, aged from 17 to 81, to create what they call “germline stem cells.” More exactly, they collected these tissues, isolated the cells that produce sperm cells and then cultured them in growth media containing factors that support the development of human embryonic stem cells. Few weeks later, the researchers discovered that the cells took on many of the genetic and growth characteristics of embryonic stem cells.

The most exciting thing that happened was the sight of the germ cells growing in colonies that resembled stem cells. When these cells were injected into laboratory mice, they were able to grow cartilage, muscle, nerve cells and there is a possibility of growing an entire new organ.

“The advantage these cells have in comparison to embryonic stem cells is that there is ethical problem with these cells and that they are natural,” Dr. Skutella said.

Scientists see the findings as promising but there is no reason to give up on research on embryonic stem cells as the German study found a solution for males and left women without as easy a method, stem cell scientist George Daley of Children's Hospital in Boston and the Harvard Stem Cell Institute, said.

On the other hand, Dr. Skutella said female equivalent could be in women’s egg cells.

If further research shows that the cells resulted are normal, it could allow men to grow their own tissue for transplant. Cells could be taken from a Parkinson’s disease patient’s testicles, nurtured in a laboratory and turned into brain cells. The resulted cells could be further implanted into his brain to replace those lost to the disease. Moreover, the same method could be used to create heart, pancreatic or liver cells.