Multiple sclerosis, or MS, occurs when the body attacks the fatty material that insulates the nerves, called myelin.

Nerves carry messages from the brain to different parts of the body, just as electrical wires carry electricity.

The body has ways to replenish the supply of myelin, but over time this process breaks down.

A person's condition degenerates as more myelin is stripped, leaving damaged nerves unable to transmit messages from the brain.

This slow degeneration is responsible for the progressive increase in disability in people with MS.

FOUR months after a controversial stem cell transplant, Launceston cop, father of three and MS sufferer Michael Mitchell is fighting fit.

Diagnosed with the autoimmune disease multiple sclerosis in 2003 at the age of 33, Mr Mitchell is the first Tasmanian to undergo the potentially life-saving procedure.

It appears to not only stop the debilitating disease in its tracks, but may also reverse it.

In November, he had the transplant at the Canberra Hospital at the hands of Dr Colin Andrews, one of two neurologists in the country performing the procedure.

It involves chemotherapy to destroy faulty white blood cells and to get the bone marrow to produce new stem cells.

The new stem cells are then taken from the blood, frozen and stored.

Another heavy dose of chemo is used to kill the faulty T-cells in the blood cells.

The transplant then puts back the harvested stem cells, and the bone marrow starts to produce healthy blood cells.

The procedure virtually reboots the body's immune system, leaving patients open to the risk of fatal infections.

"It was hardcore," he said.

"I don't know if I could go through it again.

"It's basically the closest you can get to death without dying."

Today, Mr Mitchell is less fatigued and can spend time playing with children Luke, 12, Sam, 6, and Lily, 3.

"Every week I feel stronger," he said.

"I'm certainly one of the lucky ones."

Dr Andrews said ideal candidates for the transplant were below 40 with an aggressive form of the disease, relatively recent onset and where conventional treatment had failed.

In Australia, more than 20,000 people are affected by MS. Research has shown that Tasmania has the highest incidence of MS in the country.