WASHINGTON - Researchers have found a way to directly convert spermatogonial stem cells, precursors of sperm cells, into tissues of the prostate, skin and uterus.

Their approach may prove to be an effective alternative to the medical use of embryonic stem cells.

The hunt for alternatives to embryonic stem cells has led to some promising yet problematic approaches, some of which involve spermatogonial stem cells (SSCs).

Researchers recently observed, for example, that lab-grown SSCs will eventually give rise to a few cells that look and act like embryonic stem cells.

This process can take months, however, and only a small percentage of the SSCs are converted into “embryonic stem (ES)-like” cells.

The new method, recently developed at the University of Illinois (U-I), 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.

For example, when researchers put bladder epithelial cells on the mesenchyme of a prostate gland, the bladder cells were changed into prostatic epithelium. The prostatic mesenchyme had altered the fate of the bladder.

“The mesenchyme - it’s the director; it’s controlling the show,” said University of Illinois (U-I) veterinary biosciences professor Paul Cooke, who led the new study with researcher Liz Simon.

These findings have been described in Stem Cells.