Researchers have successfully injected stem cells into the brain of a 64-year-old Victorian man as part of a trial treatment for Parkinson's disease, that they say is the first of its kind in the world.

Key points: Parkinson's disease affects 80,000 Australians

Parkinson's disease affects 80,000 Australians Parkinson's occurs when there is a shortage of dopamine in the brain

Parkinson's occurs when there is a shortage of dopamine in the brain Recent trial millions of stem cells were injected at 14 sites in the patient's brain

So far there has been no drug developed to stop the progression of Parkinson's, which affects 80,000 Australians.

And the researchers at the Royal Melbourne Hospital said because the stem cells were created in a lab, the ethical dilemma of using them was avoided.

Usually the surgical treatment for Parkinson's is deep brain stimulation, with neurosurgeons drilling holes into a patient's skull and putting wires into two parts of the brain.

But in the most recent trial, millions of stem cells were injected at 14 sites in the patient's brain, Garish Nair, a neurosurgeon at the Royal Melbourne Hospital, said.

He said before the human trial he and his colleagues spent weeks practising on a 3D model.

"The challenge was to do it in a way that you minimise the number of times that you pass your instrument through the brain, to minimise the damage," Dr Nair said.

"So we had to actually plan out a new methodology of doing it. I think we did about three or four dummy runs before we were confident that we got it perfectly right."

He said their hope was that the stem cells would boost levels of the neurotransmitter dopamine.

"So Parkinson's is a disease which comes because of a shortage of dopamine in the brain," he said.

"The symptoms are a tremor, rigidity, and being unable to express emotions, affecting walking. All of those functions are mediated by dopamine.

"We will monitor these patients to see if they are having any improvement in their Parkinson's symptoms."

Ethical dilemma of using stem cells avoided

Dr Nair said the trial would also sidestep the ethical dilemma involved in using stem cells because it was using neural cells manufactured in a lab by a Californian biotech company.

"Stem cells have always had an ethical problem behind it, because you traditionally have been getting it from what is called embryonic stem cells, so you need to get it from embryos that have died," he said.

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"So the beauty of this technique is that this is an unfertilised egg activated in a lab, so there are no ethical issues surrounding this to be used as mainstream treatment down the line."

But others in the field have taken a more cautionary approach, and have questioned whether stem-cell-based therapies are really ready for clinical trials.

A paper published in March, with the contributing author from Melbourne's Florey Institute, warned: "Unless pre-clinical data and regulatory approvals were obtained, premature trials in humans could tarnish many years of scientific work and threaten to derail this exciting field of medicine."

But the trial's researchers said they had ethics approval, Therapeutic Goods Administration (TGA) approval and said pre-clinical trials were conducted on monkeys, as well as on more than 400 mice.