Will Ultrasound-Guided 3D Printing Inside the Body Lead to Better Treatment of Diseases?

A recent study by American researchers has led to the development of a method of 3D printing directly into the body using ultrasound. In concrete terms, the team would be able to inject 3D shapes loaded with cells into the body and, using ultrasound, bring them closer to where treatment is needed. The aim is to administer drugs or the right cells as close as possible to a disease. Initial tests have been successfully carried out on mice and rabbits, suggesting that it may be possible to repair damaged tissue directly in their bodies. The technique, dubbed deep tissue in vivo sound printing (DISP), represents a major breakthrough for the medical additive manufacturing sector.

As we all know, 3D technologies are one of the most useful resources in the healthcare sector. They can be used to design tailor-made implants to be integrated into the human body, or tissue directly onto the skin, for example. However, the need for invasive surgical implantation is more often than not necessary and adds to the complexity of the whole process. That is why a team of scientists at the California Institute of Technology (Caltech) have come up with a printing platform that uses image-guided ultrasound to place 3D materials deeper into the body. Unlike infrared light, for example, ultrasound is able to penetrate muscles and organs.

Diagram of the DISP process (photo credits: Elham Davoodi and Wei Gao)

Ultrasound-Guided 3D Printing: Operation and Testing

The researchers used a focused ultrasound beam and a specially formulated bio-ink. The latter is a hydrogel formed by polymer chains and cross-linking agents. In addition, ingredients specific to the disease to be treated are added. The cross-linking agents are encapsulated in liposome-based particles. These are lipids whose outer envelopes disappear under the effect of heat (around forty degrees). These liposomes prevent the bio-ink from forming as soon as it is deposited, thus enabling better control of cross-linking and increasing its speed. The team was thus able to create stars and drops of water.