A high-performance material has been developed to fight osteoporosis and infections and cement fractures, writes HELEN GALLAGHER
FROM sugar-like particles that serve as bone cement to sponge-like rods strong enough to carry your weight, intensive efforts are under way to discover new materials that can substitute for damaged bone.
The terminology used might sound like arts and crafts, but Irish research into human bone repair is far from child’s play.
Dr Daniel Boyd of the Medical Engineering Design Innovation Centre (Medic) in Cork Institute of Technology collaborated with Dr Mark Towler of the Materials and Surface Science Institute in University of Limerick to develop a new kind of bone replacement.
“Enterprise Ireland has invested over €400,000 in funding for the Promex project to deliver this innovative product,” says Boyd. “Typically bone is taken from an area in the body where it does not serve a critical function, such as the pelvis, and transplanted to another, where it is needed to add strength and help with healing. This is traditionally known as a bone graft.”
The Promex product takes a novel approach. “With this project we decided to produce a bone graft with built-in bone enhancing properties, but we have also included a very effective anti-bacterial agent to prevent infections,” Boyd says.
Bones may need to be repaired or reconstructed as a result of illness, injury or as part of a surgical procedure. “These grafts have many uses not only for those with osteoporosis, but where removal of bone is done because of bone cancer, or even removal of wisdom teeth.”
Alternatives to self grafting use either bone donated by a second person, or man-made bone grafts made of synthetic materials.
“These procedures can be costly and traumatic for the patient. They carry considerable risks because of the second surgical site, and also the potential for infection from donated bone,” he explains.
There are a number of ceramic bone replacements available. “Many are made from hydroxyapatite material. The main problem with these is that when used in patients with osteoporosis, the implant can become encased in osteoporotic tissue which can weaken it.”
The Promex graft contains a drug to repair bone from the inside out. “What our product does is leverage a powerful drug called strontium ranelate which heals the bone. If administered at the right levels, it has been shown to reduce the risk of fracture in osteoporosis patients by up to 60 per cent,” says Boyd.
“Strontium is released from the graft material over the period of weeks into the bloodstream. It turns off the cells which dissolve bone or osteoclasts, and turns on the cells which repair and rebuild bone or osteoplasts, building healthy bone around the graft.”
The Promex material also contains an anti-bacterial agent which is very effective in preventing infections.
“The zinc safeguards against infection which is a risk with any surgery, but a particular threat associated with donated bone.” In 2001 the US Centres for Disease Control reported 26 infections out of 500,000 bone transplants, which is a low rate, but one of these people contracted HIV, so that puts the risk in context,” he says.
“Another consideration is that we are all living a lot longer, so the quality of bone donated is lower as a result, which is also driving the need for good synthetic bone grafts.”
These new grafts are highly adaptable to different situations. “Promex can be used as ‘particulate grafts’ so it looks like table sugar and has immediate uses for non-load-bearing defects in bone, as well as mixing with harvested bone as a bone extender or a packing agent,” explains Boyd.
“We are also working on grafts in rod or foam form, so it is porous like a kitchen sponge and the bone grows through it and strengthens to support load bearing defects.”
The researchers are very eager to commercialise this product and are patenting their discoveries. “We are currently reviewing options to start a research and high end manufacturing company by the end of the year,” says Boyd.