Using high-frequency sound waves directed at human stem cells, researchers have been able to grow bone cells in a procedure that could one day help patients regrow bone tissue. The new method uses the body’s innate ability to heal itself to grow bone cells quickly, skirting around the existing issue of painful procedures and low volume that current methods have. 

“The sound waves cut the treatment time usually required to get stem cells to begin to turn into bone cells by several days,” said co-lead author Dr Amy Gelmi, a Vice-Chancellor’s Research Fellow at the Royal Melbourne Institute of Technology (RMIT), in a statement. 

“This method also doesn’t require any special ‘bone-inducing’ drugs and it’s very easy to apply to the stem cells.” 

Their method was outlined in a study published in the journal Small. 

An emerging field of biology called tissue engineering is interested in the regeneration, restoration, or improvement of biological tissues, and researchers from RMIT are particularly focused on regenerating bone tissue for patients that lost it from cancer or degenerative diseases. However, research into restoring bone tissue has struggled to efficiently turn the large quantities of stem cells necessary into bone cells. Other studies have used bone marrow stem cells, but these are extremely painful to extract. 

One alternative method is the use of sound waves to trigger stem cells to differentiate into different cell fates, though this has previously been limited to low frequencies applied over a long time period.  

Unperturbed by the unconventional use of MHz-order frequencies compared to KHz, the researchers developed a small, scalable device that can deliver rapid treatments of high frequency bursts to stem cells. When tested on adult stem cells, the researchers could accurately trigger the differentiation of stem cells into bone cells over just five treatments of 10 minutes each day. 

“Our study found this new approach has strong potential to be used for treating the stem cells, before we either coat them onto an implant or inject them directly into the body for tissue engineering,” continued Gelmi. 

The device is also scalable and cheap, allowing the development of a much larger device that could engineer large quantities of stem cells. It uses fat-derived stem cells as an alternative to marrow cells, which are significantly easier and less painful to extract. 

“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 Distinguished Professor Leslie Yeo, co-lead author of the paper, added. 

“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.” 

The researchers believe that using this type of treatment, it is possible that future healthcare could allow for the regeneration of lost bone tissue in cancer patients. In hopes of massively upscaling the process, the team are now looking to develop a bioreactor that can efficiently drive stem cell differentiation in large quantities.