Human cells used to treat 'Parkinson's' rats

Human embryo cells have been used to treat rats with symptoms of Parkinson’s disease in a move that has important implications for therapeutic cloning, it was revealed today.

Scientists in Israel manipulated the stem cells in the laboratory before injecting them into the rats’ brains.

The cells developed into specialist neurons that are missing in Parkinson’s patients, and reduced behavioural symptoms in the animals.

Stem cells taken from cloned human embryos could provide a future cure for brain diseases such as Parkinson’s and Alzheimer’s, as well as diabetes, heart damage, and many other conditions.

Today scientists welcomed the new research but warned that much more work was needed to ensure that treatment with human embryonic stem cells was safe.

One study presented today at the annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Berlin found significant genetic abnormalities in cloned mice.

Scientists at Newcastle University are waiting for permission to start cloning human embryos for research for the first time in Britain.

Research regulator the Human Fertilisation and Embryology Authority (HFEA) has asked the team for more information before coming to a decision.

The scientists hope to use stem cells from cloned human embryos to create insulin-secreting cells with which to treat diabetes.

Stem cells are “master cells” which can be stimulated to develop into different kinds of tissue.

Those extracted from pinhead-sized early stage embryos have the potential to become any kind of tissue in the body, including nerves, muscle, bone and organs.

Animal embryonic stem cells have been used to treat animal versions of Parkinson’s before, but the research presented today was the first to involve human cells.

Dr Benjamin Reubinoff, from Hadassah University Hospital in Jerusalem, told the ESHRE meeting: “This study shows for the first time that human embryonic stem cell-developed neural precursors can induce partial functional recovery in an experimental model of Parkinson’s disease.

“We believe that these observations are encouraging, and set the stage for future development that may eventually allow the use of embryonic stem cells for the treatment of Parkinson’s disease.”

But he said more extensive studies were needed to determine the safety of treatment with human embryonic stem cells.

Rats with Parkinson’s symptoms exhibit behavioural traits such as continually turning and failing to make side steps when dragged across a surface.

These symptoms were significantly reduced in rats given the stem cell transplants. The cells did not continue proliferating and differentiating in the rats, which might have dangerous consequences, and did not generate tumours.

Dr Miodrag Stojkovic, who heads the Newcastle team at the university’s Institute of Human Genetics, said: “This use of human embryonic stem cells to improve the condition of rats with Parkinson’s is excellent news and underlines the huge potential of this kind of treatment.

“However, the development of treatments for humans is much more complicated, because of the difficulties in producing clinical-grade stem cells which are known to be free from contaminants such as viruses, and also the need to conduct lengthy clinical trials to ensure there are no adverse effects, such as the formation of tumours.”

Last year a Korean team led by Dr Shin-Yong Moon, from the National University of Seoul, announced the production of the first stem cell line derived from cloned human embryos.

Today he said work was continuing to improve the technique. “Our first attempt was clearly not very efficient,” he told the ESHRE meeting.

“We only managed to harvest one stem cell line. We do not know whether this was due to something going wrong in the development of the cloned embryo, or whether we need to make small variations in our experimental procedures. But this will become clearer as we proceed.”

Dr Takumi Takeuchi, from Cornell University in New York, sounded a cautionary note with research showing significant genetic abnormalities in cloned mouse embryos.

His team focused on imprinting, the process by which genes inherited from only a particular parent are activated in offspring.

He told the meeting: “We found significantly impaired development in the cloned embryos compared with those derived from conventional ART (assisted reproduction technology) techniques, and this has made us more convinced that reproductive cloning is unsafe and should not be applied to humans.”

Professor Andre Van Steirtegheim, executive director of ESHRE, said it was vitally important to investigate such genetic functioning – or “epigenetic” - problems before moving on to applying the technology to human treatments.

“It would be a grave mistake if there was something wrong with the epigenetics of these stem cell lines to transfer them back into patients,” he said.