A Scientific American special issue focuses on stems cells with a brace of articles and opinion pieces. Good stuff. "Stem cells serve as a biological repair system, with the potential to develop into many types of specialised cells in the body. They can theoretically divide without limit to replenish other cells. When a stem cell divides, each daughter can remain a stem cell or adopt a more specialised role such as a muscle, blood or brain cell ... Controlling this differentiation process is one of the biggest challenges in stem cell research. ... Biologists believe most degenerative diseases are too complex to treat effectively just by giving patients drugs or even gene therapy. Living cells, which produce a far larger number of biologically active molecules, stand a better chance of success."

Link: http://www.sciam.com/print_version.cfm?articleID=000BB369-6D99-12B8-AD9983414B7F0000