New technique advances embryonic stem cell alternative

Boston, Mass., Sep 27, 2008 / 22:07 pm

Researchers have refined an experimental process that could produce stem cells without needing to create and destroy human embryos. The process turns adult cells into what are called induced pluripotent stem cells (iPS cells) believed to have high potential for therapeutic treatments for many severe medical conditions. New research has reportedly eliminated iPS cells’ tendencies to become cancerous.

"We have removed a major roadblock for translating this into a clinical setting," Harvard University stem cell researcher Konrad Hochedlinger told the Washington Post.

"I think it's an important advance," he continued.

Hochedlinger and his fellow researchers published their research online yesterday in the journal Science.

Last year scientists discovered how to generate iPS cells by introducing four genes into mice adult cells using retroviruses. The genes changed the cells into a state similar to that of embryonic stem cells.

However, such retroviruses can cause cancer in animals and can integrate their own DNA into that of the host cells.

Hochedlinger and his colleagues used a different virus, called an adenovirus, to introduce the same four genes into mice adult cells.

"The adenovirus will infect the cells but then will clear themselves from the cells. After a few cell divisions there are no traces of the virus in the cell," Hochedlinger said, according to the Washington Post. "You can't tell the virus was ever there."

Tests showed that the cells produced by the new method were indistinguishable from embryonic stem cells and could be transformed into any type of tissue such as lung, heart, brain, and muscle.

Unlike the retrovirus-treated cells, the adenovirus-treated cells do not produce cancerous tumors.

"What our experiment shows is you can do this without an integrating virus. You do not need integration of the DNA into the genome to produce iPS cells," Hochedlinger said.

Robert Lanza, a stem cell researcher at Advanced Cell Technology in Worcester, Mass., called the research a "huge step forward," saying the cancerous properties of earlier iPS cells prevented clinical therapies from being developed.

"The use of iPS cells to treat or even cure human disease may not be far away," Lanza told the Washington Post.

Rudolf Jaenisch, a professor of biology at the Whitehead Institute in Cambridge, Massachusetts, praised the new findings but said the new process is 100 times less efficient than the retrovirus technique.

According to the Washington Post, Hochedlinger said his team is trying to streamline the production process, perhaps by supplementing the new genes with chemicals that flip biological switches.

Critics of embryonic stem cell research praised the findings as evidence that ethically questionable embryonic research is unnecessary.

"This is the latest in a line of studies showing that the practical problems associated with using 'reprogrammed' adult cells are rapidly being solved," Richard Doerflinger of the U.S. Conference of Catholic Bishops said in an e-mail to the Washington Post.

Hochedlinger and others argue research on embryonic stem cells must continue because it is unclear whether other stem cell therapies will prove effective.