A new method to directly convert male germ cells-spermatogonial stem cells, the precursors of sperm cells-into other cell types like tissues of the prostate, skin and uterus has been developed by researchers at the University of Illinois.
The new approach might prove to be an effective alternative to the medical use of embryonic stem cells.
Recent researches involving spermatagonial stem cells (SSCs) have proved to be quite promising as well as problematic in the hunt for alternatives to embryonic stem cells.
However, the new method takes advantage of the unusual interaction of two tissue types-the epithelium and the mesenchyme.
The epithelium lines the cavities and surfaces of glands and many organs and secretes enzymes and other factors that are essential to the function of these tissues. The mesenchyme is the connective tissue in embryos.
In the 1950s, scientists discovered that the epithelium takes its developmental instructions from the mesenchyme.
"The mesenchyme - it's the director; it's controlling the show," said Dr. Paul Cooke, who led the new study with postdoctoral researcher Liz Simon.
The researchers began the effort with what they considered to be an unlikely proposition.
"Could we take spermatagonial stem cells and cause them to directly change into other cell types by putting them with various mesenchymes and growing them in the body? I thought it was possible, but I didn't think it would work," said Cooke.
However, the experiment did work-when Simon placed SSCs from inbred mice on prostate mesenchyme and grafted the combination into living mice, the SSCs became prostatic epithelium.
When combined with skin mesenchyme and grown in vivo, the SSCs became skin epithelum.
The researchers could also convert SSCs into uterine epithelium by using uterine mesenchyme.
The newly formed tissues had all the physical characteristics of prostate, skin or uterus, and produced the telltale markers of those tissue types, said Cooke. They also stopped looking and behaving like SSCs.
Cooke is hoping that a more streamlined approach can be developed that makes use of a man's own SSCs and stroma (the adult equivalent of the mesenchyme) to produce new skin cells or other tissues when needed - for example, to replace skin damaged in a burn.
The researchers are currently investigating the use of ovarian stem cells instead of SSCs to see whether the same results can be obtained with ovarian tissue.
The study has been published this month in the journal Stem Cells.