Are we on our way to regenerate human body parts?

Aussie researchers announced a breakthrough in regenerative stem cell medicine this week - but what does it actually mean?

Scientists have managed to take cells from adult mice and turn them into multipotent stem cells capable of growing different kinds of tissue.

It’s been hailed as a breakthrough that could lead to safe regenerative stem cell therapies - and here’s what you need to know about it.

What’s a stem cell?
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When we talk of stem cells, we normally mean a type of basic, unspecialised cell that can divide and renew itself over a long period of time and carries the amazing potential to turn into any type of cell that comprise the tissues and organs in our bodies.

In its earliest stages, an embryo is full of stem cells - these cells divide, send and transmit signals, and go on to turn into eyes, muscles, blood and many other things we possess as fully grown beings. Such cells are called embryonic stem cells, and scientists first derived them from mouse embryos back in 1981.

We also have adult stem cells - these occur in different parts of the body in small quantities, but their ability to turn into anything is less powerful. Stem cells found in bone marrow only give rise to all kinds of blood cells, but you couldn’t use them to make, say, cartilage or muscle.

What about induced multipotent stem cells?
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The stem cells produced in the latest experiments by UNSW researchers are induced multipotent stem cells (iMS). They’re ‘induced’ because the researchers took normal cells that already have their specialisation - such as being a fat cell - and reverted them into cells that could actually produce various tissues.

“We have taken bone and fat cells, switched off their memory and converted them into stem cells so they can repair different cell types once they are put back inside the body,” says lead author of the study, Associate Professor John Pimanda.

The study was led by researchers from the University of New South Wales published this week in Proceedings of the National Academy of Sciences.

“This method involves culturing fat or bone cells with a drug called Azacitidine and a naturally occurring growth factor called platelet-derived growth factor,” the authors explain in an article for The Conversation.

“We think the combination of erasing the cell’s memory with Azacitidine and forcing the cell to proliferate with the growth factor are key to converting fat and bone cells into induced multipotent stem cells."

 

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So what do stem cells have to do with therapy?
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Because a stem cell can turn into any kind of cell provided it lands in the right environment, theoretically this means we could use these cells for regenerative medicine.

So, instead of replacing your dodgy knee, an injection of appropriate stem cells in the right spot could cause the knee to grow the right kind of tissue to replace the damaged bits.

Such attempts at regenerative medicine are in their infancy, and the wrong kind of stem cell plopped into the wrong part of the body could lead to unwanted side-effects, not to mention unwanted growths and, at worst, even cancerous tumours.

However, the researchers claim that stem cells produced with their new technique are safe and do exactly what you’d expect.

“The exciting next experiment showed that the mouse bone derived stem cells can be transplanted back into damaged spine tissue and repair damage to the bone, muscle and ligaments and even blood vessels in the spine,” says Dr Bryce Vissel from the Garvan Institute for Medical Research.

 

Are we going to be regenerating limbs?
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Not so fast. While this study was done in mice, the researchers are also looking into applying this research to human cells. So far they’ve taken human fat cells, reprogrammed them into iMS cells and injected them in mice to see whether they can treat injuries.

This step is necessary to assess the safety of these cells before starting human trials, however the scientists are hopeful this might work just fine.

“Our initial clinical focus will be using induced multipotent stem cells either as a stand-alone treatment or with spinal implants to treat degenerative disc disease towards the end of 2017,” write the researchers.

However, Professor Martin Pera, Chair of Stem Cell Sciences at the University of Melbourne, is a little more sceptical.

“The observations are interesting, but the study does not demonstrate that these cells have properties similar to pluripotent stem cells derived from embryos or through reprogramming,” he says. “It will be some time before the therapeutic implications of this work become clear.”

Watch this space.