Polymers may ease the pain of broken bones.

While it is notoriously difficult to define a living organism, biochemists have added an oddly pragmatic point of view to the complex metaphysics: organisms are little more than an inspired amalgamation of a rather dull class of molecules – polymers.

In a physical sense, these are long and very repetitive molecules; long chains built by linking simple building blocks end on end. But the class includes the likes of DNA and proteins that have high information content. However, while defining a human in this way would never satisfy the philosophers, the polymer approach does come with interesting medical ramifications.

In fact, two of the issues that concern hospital patients the most – the invasiveness of a procedure and disability during recuperation – could each be improved considerably by going the polymer route.

Dr Thilak Gunatillake, at CSIRO’s Molecular Science division, explained the situation with regards to a broken bone. According to scientists, the metallic pins and screws currently in use by surgeons have a number of drawbacks. Especially designed, synthetic and biodegradable polymers may provide a better option.

The goal is to reach into the body with little more than a syringe and needle containing a liquid gel (NovoSorb). Applied at the fracture, the gel cures into a polymer that glues the fractured bone together and mechanically supports it while the polymer aids and abets the healing process.

Rather than needing follow-up surgery to remove pins, the polymer is designed to naturally degrade at a rate that coincides with healing.

Each of these properties – reduced invasiveness, curing from a liquid to a polymer form, mechanical strength, recruitment of cells that aid healing, biodegradability – is made possible because they are intrinsic to the design of a polymer from the polyurethane family.

Despite very promising results in animal trials, it is generally a long way from a lab discovery to a clinically available medical procedure. However, thanks to an innovative CSIRO commercialisation program, Dr Gunatillake and his team will not have to sacrifice their lab work to make that journey.

While the scientists pursue the design of novel polymers, over the past year CSIRO has invested the intellectual property in a start-up company called PolyNovo Biomaterials. In May 2004, Xceed, an Australian Stock Exchange (XBL) listed biotechnology investment company, supplied $5.1 million in exchange for 50 per cent of PolyNovo equity.

With these funds, PolyNovo is actively overseeing product development. Executive Officer Dr Ian Griffiths explained this as a three-stage process. First PolyNovo hopes to start co-developing devices using NovoSorb in conjunction with medical device companies. Then the pre-clinical trial will determine product safety. Full clinical trials are then required to assess product efficacy. If all goes well, PolyNovo’s first product could receive market approval in three to five years.

The development of a fully biodegradable stent is of high priority in PolyNovo’s product development plan. 'A certain percentage of heart patients experience re-blockage of the coronary artery following the insertion of a stent', explained Dr Griffiths.

While coating stents with anti-inflammatory agents is useful, PolyNovo is 'designing materials suitable for a device that keeps the vessel open, and once remodelling and natural healing occurs in two to three months, the stent is re-absorbed and degraded'.

In contrast, the bone-fracture orthopaedic polymer is about 18 months behind the stent in the commercialisation process.

There is also a third variation for use in surgical situations. Cured by the use of blue light, these polymers can fill gaps in more complex fractures.

However, the story does not end there. Tissue engineering, wound care and drug delivery are further examples of medical procedures that could hitch a ride on PolyNovo’s polymer technology.

For further information contact:
CSIRO Enquiries
Email: Solve@csiro.au      Web: www.csiro.au
Tel: 1300 363 400       International: +61 3 9545 2176

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Last Updated: February 10, 2005
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