Researchers at North Carolina University (NC, US) have developed a technique which improves the characteristics of engineered tissues. The device uses ultrasound waves to align the living cells as they are laid down during the biofabrication process.
Prior to this breakthrough researchers have struggled to organize the cells that are being printed in engineered tissue. However, the novel technology developed by researchers at North Carolina University (NC, US) can provide this level of control creating implants that are accurate mimics of natural tissue structures.
“We’ve now developed a technique, called ultrasound-assisted biofabrication (UAB), which allows us to align cells in a three-dimensional matrix during the bioprinting process. This allows us to create a knee meniscus, for example, that is more similar to a patient’s original meniscus. To date, we’ve been able to align cells for a range of engineered musculoskeletal tissues,” Explains Rohan Shirwaiker, corresponding author of the paper and an associate professor in Edward P. Fitts Department of Industrial & Systems Engineering (NY, US).
The UAB technology consists of an ultrasound chamber that allows ultrasonic waves to travel across the area where the bioprinter prints living cells. The ultrasound waves travel in one direction from the sources, before being reflected back in the same way creating a “standing ultrasound wave” which herd the cells into rows. The researchers also discovered that by altering the frequency and amplitude of the ultrasonic waves they could further control the alignment characteristics of the cells.
To demonstrate how effective the UAB technique is the researchers printed a knee meniscus. The use of ultrasound standing waves in the printing process caused the cells to align in a semilunar arc that mimicked closely the natural meniscus found in a human knee.
“We were able to control the alignment of the cells as they were printed, layer by layer, throughout the tissue,” added Shirwaiker “We’ve also shown the ability to align cells in ways that are particularly important for other orthopedic soft tissues, such as ligaments and tendons.”
The researchers have also discovered that some combinations of ultrasound parameters resulted in cell death. “This is important, because it gives us a clear understanding of both what we can do to improve tissue performance and what we need to avoid in order to preserve living cells,” commented Shirwaiker.
A final benefit of the UAB technology is that it is relatively inexpensive.
“There’s a one-time cost for setting up the ultrasound equipment — which can use off-the-shelf technology. After that, the operating costs for the ultrasound components are negligible. And the UAB technique can be used in conjunction with most existing bioprinting technologies,” Concluded Shirwaiker.
The future is looking promising for the UAB technique with a patent pending the researchers are now looking for an industry partner to develop its use commercially.