Sir Bob Geldof has an amazing history.
He went from rock star to world crusader, creating the first super group to aid hunger in Africa. Since his "We Are The World Days" he's been the world, adding Live Aid, Live 8 and other major fundraisers to his inventory.

So what could bring this icon to Toronto on Wednesday?

The answer is the opening of the McEwen Centre for Regenerative Medicine. It's headed by one of the world's leading experts on the controversial area of stem cells, Dr. Gordon Keller.

And it's become another pet cause for the former Boomtown Rat, who has friends with Alzheimer's disease and Multiple Sclerosis, conditions that experts believe can both be helped and alleviated with stem cells.

They're essentially cells that haven't decided what they want to be when they grow up. And that means they can be used to repair and regrow almost any tissue in the body, something akin to human spare parts.

"Here you have a cell that you can tell to make any cell type in our body in a culture dish," explains Keller.

Geldof is impressed and is advocating for more widespread use of the technology. "You can tangibly feel the unfolding century when you come to places like this," he marvels.

But not everyone agrees it's such a big step forward, especially for those who have religious concerns. They complain that the cells come from unborn embryos. And that makes the harvesting mortally wrong.

"Embryonic stem cell research has been unsuccessful," argues Natalie Hudson of the Right To Life. "We can't use it in human patients. It's diverting resources away from adult stem cell research, which is much more viable."

The dispute has been ongoing for years and despite Geldof's hearty endorsement and assurances from many medical experts that it may be the so-called magic bullet that can cure a host of diseases, it remains mired in controversy and stuck in an ethical limbo.