A new way of delivering stem cells could one day lead to a single injection to mend broken or diseased bones and joints, French and Australian scientists say.
Dr Frank Caruso of the Centre for Nanoscience and Nanotechnology at the University of Melbourne and colleagues report their findings this week in the Proceedings of the National Academy of Sciences.
"It is growth factor and stem cells in an injectable format," says Caruso.
"This would be used wherever you would like to regenerate bone."
Bone and joint problems are particularly challenging for medical scientists because bone cells sometimes don't heal themselves very well.
For this reason researchers are exploring ways to effectively transplant stem cells that will regenerate bones and joints.
Caruso and colleagues have designed a capsule made of synthetic polymers, which they have impregnated with growth factors that stimulate the differentiation of stem cells into bone cells.
He says the capsules are very tiny - ranging from about 100 nanometres to tens of microns.
The researchers have then combined these capsules with embryonic stem cells in a matrix of alginate gel. They injected the mixture into lab animals and demonstrated they can stimulate bone regrowth.
If ongoing experiments prove positive, Caruso says the development may lead to treatments in 5 to 10 years.
Caruso says the team plans to engineer the capsule to control the release of the growth factors, which might otherwise be quickly degraded by the body, avoiding the need for multiple injections.
"The aim is to have a one-dose therapy," he says.
Associate Professor Stan Gronthos of the Centre for Stem Cell Research at the University of Adelaide says this could be a major benefit of the aproach.
"The actual engineering of the capsule is the interesting bit in this," says Gronthos, who is currently involved in second phase trials with a commercial company, surgically implanting adult stem cells and growth factors to regenerate bone in animals and humans.
Stem cell scientist Dr Paul Verma of Monash University in Melbourne describes the capsule of growth factors like a "slow release fertiliser".
He says, if it works, it will reduce the amount of expensive growth factors required in stem cell treatments.