Stem cell breakthrough

Nope, not with embryonic stem cells. Their scorecard still reads a big, fat zero.

WEDNESDAY, Oct. 22 (HealthDay News) -- Using just a single adult stem cell, scientists say they have grown entire prostates in mice.

This feat was made possible by the identification of a genetic signature distinguishing stem cells from other types of cells, according to a report in the Oct. 23 issue ofNature.

This information still has to be confirmed in humans, but understanding normal cells should eventually lead to an understanding of how prostate cancer develops.

"It's another step showing that stem cells can be a root case of a cancer . . . so it gives targets for treatment," said Dr. Darwin Prockop, the Stearman Chair in Genomic Medicine, a professor of molecular and cellular medicine at Texas A&M Health Science Center College of Medicine, and director of the Institute for Regenerative Medicine at Scott & White in Temple, Texas.

This provides ways to understand prostate cancer that might be related to stem cells," added Paul Sanberg, distinguished professor of neurosurgery and director of the University of South Florida Center of Excellence for Aging and Brain Repair in Tampa.

Stem cells have the ability to differentiate into many types of cells in the body. As such, they hold the promise of leading to treatments, and possibly, one day, even cures for neurological and many other diseases.

Many scientists believe stem cells in normal tissue are the same cells that give rise to cancer. But study co-author Leisa Johnson, a senior scientist with Genentech in San Francisco, said that point has not yet been proven.

In rodents, the normal prostate undergoes up-and-down cycles of androgen (a male hormone), indicating to researchers the presence of prostate stem cells. But how to identify them?

Several markers have been reported on the surface of these stem cells, but they also are present in other cells, making differentiation difficult.

The authors of this paper found a new marker, CD117, which, when combined with previously known prostate stem cell cancer markers, could identify a single, normal prostate stem cell.

That single stem cell was able to generate functional prostates and was also capable of renewing itself.

"We are trying to first define what is the normal cell compartment that can generate a tissue," Johnson explained. "Once we have that knowledge, is it that compartment that goes awry when cancer initiates? What is the resistant population, and what is regenerating a tumor? Is it the same cell responsible for generating normal tissue?" she said.