Researchers race to strip stem cells of cancer risk

— -- The race to craft stem cells that have the virtues, but not the notoriety, of their embryonic brethren faces its final hurdle: becoming safe enough to help patients.

Researchers have unveiled a flurry of advances in recent months in the development of "induced pluripotent" stem cells. "The induced pluripotent stem cell field is probably one of the most fast-moving areas in all of biology," says researcher Leonard Zon of Children's Hospital in Boston.

Grown from adult skin, these cells are genetically transformed to have the same unspecialized function that makes embryonic cells so important. Embryonic stem cells are master cells that can grow into blood, brain, bone and every type of tissue, raising researchers' hopes of a "regenerative medicine" era in which physicians could grow organs for transplant candidates or tissue to treat spinal injuries.

In January, the Food and Drug Administration approved an experimental paralysis regimen that is the first clinical trial of an embryonic stem cell treatment. But the cells have been surrounded by controversy for the past decade because they are collected by destroying an early-stage human embryo, a reality that in 2001 led President Bush to limit federal research spending. President Obama reversed that decision in March.

Induced pluripotent stem cells sidestep that controversy but have one of their own. The only genes that can change the skin cells' function are cancer genes, so any benefit would carry a deadly risk. "What the investigators have accomplished is to discover the reset button for the cell, but the way they currently press it is by hitting it hard with a ball-peen hammer," wrote University of Wisconsin biologist P. Z. Myers in 2007 in his popular science blog, Pharyngula.

The latest research has made strides in eliminating the cancer risk. "My feeling is we will have the oncogene (cancer gene) problem solved within a year to two years," Zon says.

Four different methods, same result

So far this year, researchers have revealed four ways to remove the cancer genes: