Sound waves used to regrow bone from stem cells

Using high-frequency sound waves to turn stem cells into bone cells could help patients with cancer or degenerative diseases regrow bone.

Researchers from Royal Melbourne Institute of Technology (RMIT) University, Melbourne, Australia, have used sound waves to differentiate stem cells, overcoming multiple challenges in tissue engineering. The method was effective on multiple types of cells, including fat-derived stem cells, which are less painful to extract from patients than stem cells from bone marrow.

'We can use the sound waves to apply just the right amount of pressure in the right places to the stem cells, to trigger the change process,' said Professor Leslie Yeo, co-lead researcher and professor of chemical engineering at RMIT. 'Our device is cheap and simple to use, so could easily be upscaled for treating large numbers of cells simultaneously – vital for effective tissue engineering.'

Previous studies changing adult stem cells into bone cells have used complicated and expensive equipment and struggled with mass production, making widespread use unrealistic. The RMIT team developed a low-cost microchip, which produced sound waves in the high-frequency range.

They discovered that when exposing stem cells, in silicon oil on a culture plate, to these high wave frequencies, the stem cells began differentiating to bone cells. The team proposed that stem cells can be treated in this way before they are coated onto an implant or injected into the body to grow new tissue at the site of injury or disease.

Professor Yeo and his team have researched the interaction of high-frequency sound waves with different materials for over ten years. They discovered that the ideal setting was to expose the stem cells to high-frequency signals for ten minutes a day for five days. This enhanced the levels of certain markers that showed the stem cells were converting into bone cells.

This new finding, published in Small, removes the need for drugs to drive stem cell differentiation, making the process much faster. Dr Amy Gelmi, a senior research fellow at RMIT commented: 'The sound waves cut the treatment time usually required to get stem cells to begin to turn into bone cells by several days.'

The team plans to investigate scaling up the platform to treat large numbers of cells at the same time. Their aim is to work towards the development of bioreactors to process stem cells for clinical application.