Using sound to suspend cells could be key to growing strong cartilage to repair knee damage, says the team that has developed a device to continuously hold growing cells in a sound wave.
When new tissues or body parts are required, they are usually created by covering a scaffold outlining the organ鈥檚 natural structure with the recipient鈥檚 cells. But the scaffold can degrade over time, weakening the structure of the implant.
A team led by of the University of Southampton, UK, wondered whether they could come up with a way to create artificial tissues using just the person鈥檚 cells. Cartilage was the ideal starting material as it has a relatively simple structure that is made up of a single cell type. They decided to try sound waves as the variations in pressure could be used to control where the cells end up.
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Video: Ultrasound suspends cells in bioreactor
The team sent ultrasound waves bouncing back and forth inside a tiny, fluid-filled bioreactor holding cells taken from the top of the femur. Sure enough, the growing cells accumulated in the nodes of the wave, lining up in a layer before binding together. 鈥淭he cell filaments pull the sheet into a thick, pancake-like structure,鈥� says Glynne-Jones.
Like the real thing
After 21 days the cells had become tiny sheets of cartilage with similar strength to natural cartilage.
鈥淲hat鈥檚 exciting is that we mechanically tested the cartilage and it鈥檚 comparable to cartilage found in the human body,鈥� says Glynne-Jones. 鈥淲e think that ultrasound is playing a key part in stimulating the cells to produce the better cartilage.鈥� That鈥檚 because the mechanical stimulation of the cells with the ultrasound can be controlled to a high degree, ensuring the correct mix of proteins are generated to create strong cartilage.
When the sheets were grafted on to a sample of damaged human cartilage they successfully fused with the existing tissue.
鈥淭he method removes the challenge of synthesising biomaterial scaffolds,鈥� says biomedical engineer at the University of Bradford, UK. 鈥淚t鈥檚 an easy, non-intrusive method that has much clinical potential.鈥�
So far, the team has only produced small patches of cartilage so they are now hoping to scale up their approach. The ultimate goal is to produce cartilage from stem cells taken from a recipient鈥檚 own bone marrow.
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