Stem cells and degradable implants encourage bone regrowth

A multidisciplinary team has developed a technique for rebuilding broken bones by inserting a degradable material and stem cells into them.

In 2012 a Glaswegian team developed a polymer implant that used stem cells to graft on to the marrow inside the bone and make for a more streamlined fix. This was, however, a method for lengthening the time an implant -- such as joints in a hip replacement -- can do its job properly. One year on, and the Department of Musculoskeletal Science at the University of Southampton and the University of Edinburgh's School of Chemistry have published their proposal for effective bone regrowth around an implant.

The degradable material was generated using solvent blending, an automatic process that sees hundreds of natural and synthetic polymers mixed and tested to get the right combination of strength and flexibility.

"Several of the blend materials were found to be excellent supports for human bone marrow-derived skeletal cells and foetal skeletal cells, with the optimised blend exhibiting in vivo osteogenic potential," state the authors, "suggesting that these polymer blends could act as suitable matrices for bioengineering of hard tissues".

The material, made from three different plastics, was then built into a 3D honeycomb pattern to act as scaffolding for the bone stem cells (generated using marrow cells). Tiny holes in the material permit blood flow, feeding the stem cells which can attach themselves all around the structure to form new bones.

"Fractures and bone loss due to trauma or disease are a significant clinical and socioeconomic problem," said Richard Oreffo of the University of Southampton in a statement. "This collaboration between chemistry and medicine has identified unique candidate materials that support human bone stem cell growth and allow bone formation."

It's not the first time a solution like this has been proposed. In 2010 Paul Wooley of the Centre of Innovation for Biomaterials in Orthopaedic Research claimed to have regrown bone inside a mammal's leg using a porous composite material akin to the honeycomb now being used. According to Wooley, bone and blood vessels grew around and through the material in six weeks. It could, he claimed, mean the prevention of countless amputations.

The Southampton-Edinburgh research is novel in its use of solvent blending to get the right materials for the job. Wooley had wanted to use aviation composites, whereas in the latest piece of research every effort has been made to engineer a material effective enough to do the job, with no chance of rejection, but supple enough that it can degrade over time leaving a fully-grown piece of bone intact.

The findings have been published in the Advanced Functional Materials.

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Stem cells and degradable implants encourage bone regrowth