Researchers who used cloned embryonic stem cells to treat Parkinson's disease in mice said on Sunday they worked better than other cells.
The researchers were trying to prove that it is possible to make embryonic stem cells using cloning technology and use them to provide a tailor-made treatment.
But they found that a mouse's own cloned stem cells were far less disruptive to its body than cloned cells taken from other mice.
"It demonstrated what we suspected all along — that genetically matched tissue works better," said Viviane Tabar of Memorial Sloan-Kettering Institute in New York, who worked on the study.
"When you give the other type of tissue, non-autologous tissue, you get more inflammation than we anticipated. This is in a lab animal where we expect it to be tolerant. Normally when you do this in mice, you don't give matched cells," Tabar added in a telephone interview.
The mice given non-matched brain cells did more poorly than the mice given cells from their own clones, the researchers reported in the journal Nature Medicine.
Stem cells are the master cells of the body and embryonic stem cells are the ultimate master cells, giving rise to all the other cells and tissue. Cloning researchers hope one day to be able to take a little piece of skin and grow embryonic stem cells from it for personal, tailor-made medical treatments.
One disease always named that may benefit from this technology is Parkinson's. The incurable, fatal illness is caused by the destruction of specific brain cells.
It is sometimes treated with transplants of brain cells from cadavers or aborted fetuses. Stem cell researchers have argued that cloning technology might provide a better source of cells for treatment.
Tabar and his team first created a Parkinson's-like disease in mice using chemicals to destroy their brain cells.
They took ordinary cells from the tails of the mice, transferred the nuclei from them into hollowed-out mouse eggs cells, and made clones of the mice. This process is called somatic cell nuclear transfer, or "therapeutic cloning."
The cloned embryos were harvested for their stem cells after a few days. The researchers grew these in the lab and coaxed them into becoming the so-called dopaminergic brains cells that are lost in Parkinson's.
They put these into the brains of the injured mice. These mice got better, Tabar said.
No one has done this before. "It's incredibly hard and it involves a series of inefficient steps," Tabar said.
Several researchers have made cells that look and act like embryonic stem cells by reprogramming their genes. Tabar said her team would try using these so-called induced pluripotent stem cells in the same way.
Some people oppose using cloning technology to make human embryonic stem cells, or to creating human embryos for this purpose. It is also difficult to obtain human egg cells.
Scientists hope the induced pluripotent stem cells might provide a short cut that no one would object to.
"This is an exciting step down the pathway of creating a self-specific stem cell and getting away from the ethical demands of traditional embryonic stem cells," said Richard Boyd, Deputy Director of the Monash Immunology and Stem Cell Laboratories in Victoria, Australia.