U.S. researchers said Saturday they had transformed immature cells from men’s testicles into powerful stem cells, which they then coaxed into becoming nerve, heart and bone cells.
Their work has not been assessed by standard peer-review processes, but was presented at a meeting of stem cell researchers in Valencia, Spain. If other researchers can duplicate their efforts, the study offers a possible new source of valuable stem cells.
The researchers, at Irvine, Calif.-based PrimeGen Biotech LLC, worked with immature cells found in testes and ovaries known as germ cells. Scientists have hoped to use germ cells as a source of tissues for transplant and other medical uses.
The findings are certain to be scrutinized before they are accepted. Earlier this year, South Korean researcher Hwang Woo-Suk was disgraced for having faked two studies in which he claimed to have cloned human volunteers and used the resulting embryos as a source of embryonic stem cells.
Last week, Gerd Hasenfuss of Georg-August-University in Goettingen, Germany and colleagues reported in the journal Nature that they had transformed mouse germ cells into stem cells.
Francisco Silva and colleagues said they had accomplished the same thing, and taken it several steps further by doing the same thing with human germ cells.
“Germ cells isolated from adult human testis can be therapeutically reprogrammed to have the ability to differentiate into cells that can be used therapeutically for cell-based regenerative medicine,” they wrote for a presentation at the meeting in Spain.
“We’ve already been able to reproducibly differentiate heart, brain, bone and cartilage cells, and we are excited to begin testing how these cells incorporate into tissues,” Silva said in a statement.
Different sources of stem cells
Stem cells are the body’s master cells, and scientists are working to learn how to find and use them to replace tissue, to grow new organs, and to study diseases.
There are many different sources. So-called adult stem cells are found throughout the body, although they are difficult to identify. Bone marrow stem cells are routinely used in transplants to treat cancer and other diseases. But they are already partly programmed and can only serve as a source of a limited range of related cells.
Stem cells taken from fetuses are somewhat more flexible. The most immature cells are taken from very early fetuses called blastocysts. These embryonic stem cells are pluripotent, meaning they can serve as a source of any kind of other cells or tissue in the body at all.
Embryonic stem cells are controversial because some people believe that using them is tantamount to destroying a human life, and U.S. federal law strictly limits the use of taxpayer funds for working with them.
So researchers are seeking other sources of stem cells, both for this reason, and in the interest of finding the best possible sources for them.
Silva’s team took cells from the testes of men aged 26 to 50 years old. They grew them in various formulas of cell culture, first to re-program to act as malleable stem cells, and then to use them to grow various cell types.
“Our goal is to create the most potent cell lines to enable the most effective treatments and therapies for as many diseases as possible,” said Silva.