In a step closer to developing a treatment for Parkinson’s in humans using therapeutic cloning, scientists in the US and Japan have for the first time
used cells from a mouse to treat Parkinson’s in the same mouse.

The study is published in the advanced online issue of the journal Nature Medicine and is the work of investigators at the Memorial Sloan-Kettering
Cancer Center (MSKCC) in New York, and the Riken Institute in Kobe, Japan.

Hailed as the first study of its kind, the investigators showed that therapeutic cloning, or somatic cell nuclear transfer (SNCT), using cells from a mouse
to treat the same mouse can be successful. Although so far only demonstrated in animals, if the success is replicated in humans, it will open the door to
treatments that reduce transplant rejection and improve recovery in a range of other diseases and medical conditions.

Therapeutic cloning or SNCT involves removing the nucleus from an egg and replacing it with the nucleus of the subject. Thus the egg develops using the DNA
of the donor of the nucleus and not the donor of the egg. The egg develops into a blastocyst cell that yields embryonic stem cells with the potential to
become a range of cell types that can be used therapeutically.

Since the cells develop with the DNA of the donor of the nucleus, when implanted into the donor’s body, they will not be attacked by the donor’s immune
system.

In this new study, senior author Dr Lorenz Studer, who is Head of the Stem Cell and Tumor Biology Laboratory within the Sloan-Kettering Institute at MSKCC,
and lead author Dr Viviane Tabar, Neurosurgeon and stem cell scientist at MSKCC, used skin cells from the tails of 24 mice with Parkinson’s to create 187
cell lines, from which they derived dopamine neurons that were customized to each individual’s DNA. Dopamine neurons are brain cells that are missing or not
working effectively in Parkinson’s disease.

They then grafted the customized cells into mice with the same DNA as the cells. And another control group of mice received cells with DNA that did not match their own. The mice that received
dopamine neurons that matched their own DNA showed neurological improvement and lack of immunological response whereas those that received mismatched cells
did not.

The study has been welcomed by experts as bringing medicine a step closer toward an effective treatment for Parkinson’s, a chronic and progressive brain disease
for which there is currently no cure although there are drugs that slow and relieve the symptoms. However, some have also remarked that there is still a
long way to go before it can be said that such a treatment will be successful in humans.

Speaking to BBC News, Robin Lovell-Badge, a professor in stem cell research at the National Institute of Medical Research in London, UK, said that this study
demonstrated the potential for therapeutic cloning in the treatment of Parkinson’s, but while the successfully treated mice made a significant recovery,
they were only studied for 11 weeks, which is not long enough to tell if the treatment persists.

The Washington Post reported a comment from assistant professor Michael Jakowec, a neurologist at the George and MaryLou Boone Parkinson’s Disease and
Movement Disorders Research Center at the University of Southern California Keck School of Medicine in Los Angeles, who said that moving the science from
mice to humans is a “gigantic” step.

Jakowec told the Post that:

“You see a lot of failures in studies that try to translate success from rodents to humans.”

He suggested it might be premature to move to humans next, perhaps the method shoud be demonstrated in primates first, but there is no doubt that it opens
“a new avenue of therapeutic strategy, which may ultimately benefit patients down the road,” said Jakowec.

“Therapeutic cloning in individual parkinsonian mice.”
Viviane Tabar, Mark Tomishima, Georgia Panagiotakos, Sayaka Wakayama, Jayanthi Menon, Bill Chan, Eiji Mizutani, George Al-Shamy, Hiroshi Ohta, Teruhiko
Wakayama & Lorenz Studer.
Nature Medicine, Published online: 23 March 2008.
DOI:10.1038/nm1732

Click here for Abstract.

Sources: journal abstract, MSKCC press release, Washington Post, BBC News.

: Catharine Paddock, PhD