Scientists Use Ultrasound to 3D Print Tissues Inside Body, No Surgery Required

Scientists at the California Institute of Technology have demonstrated a method to 3D print tissues inside the body without surgery. It is referred to as deep tissue in vivo sound printing (DISP), and it uses a bioink liquid at body temperature that becomes solid with ultrasound. A molecule follows the printing, and excess bioink is broken down by the body.

To test the technology’s potential, researchers printed tissues in a mouse's and a rabbit's stomach. They also developed soft biosensors and tiny drug depots containing anticancer or antibacterial medicine that release drugs when exposed to ultrasound.

In a recent study, Imaging-guided deep tissue in vivo sound printing, published in Science, Davoodi et al. demonstrated ultrasound-guided in vivo bioprinting in murine bladders and rabbit muscle tissues.

“We validated DISP by successfully printing near diseased areas in the mouse bladder and deep within rabbit leg muscles in vivo, demonstrating its potential for localized drug delivery and tissue replacement.” said Davoodi and his colleagues.

Echoes of Innovation: Printing Tissues with Sound

3D printing is changing how scientists create artificial tissues, organs, and medical devices. Traditionally, bioprinters build these structures one thin layer at a time, using light to harden each layer. While this works, it's slow.
To overcome this, scientists have explored a faster technique called volumetric printing, which uses a focused blast of light to create a full 3D shape at once. However, light can only go so deep - just a few millimetres -because it scatters and weakens in tissue.

As Xiao Kuang from the University of Wisconsin–Madison noted, even infrared light only reaches just below the skin, limiting its use for deeper implants. Ultrasound, used in pregnancy scans, can safely reach several inches into the body. Scientists are now exploring it for 3D printing.

In 2023, Zhang’s team developed “sono-ink,” which solidifies when hit by a certain sound frequency. They printed shapes inside pig organs and repaired a goat’s heart. However, the ink was sensitive to pressure and heat, which slowed printing and affected precision. The heat from sound waves sometimes hardened the ink too early. Other ingredients also raised biocompatibility concerns.

Smarter Sono-Ink: Engineered for Precision and Control

The new system uses an upgraded version of sono-ink with several improved parts. The ink contains special molecules that float freely but stick together when triggered, along with tiny fat bubbles filled with a binding chemical, which is released when hit with ultrasound. Another part of the ink includes chemicals that help reflect sound waves and glow under certain conditions, allowing scientists to see where the ink is and if it's forming the right shape.

These changes help prevent the ink from reacting too early in the body and give better control over the printing process. The ink is either injected directly into the target area or delivered through a catheter. To test the method, the team 3D printed shapes like stars, pinwheels, teardrops, and lattices inside different types of tissue, including thick pork and chicken.

Unlike older light-based techniques that only worked on fatty tissues, this new technology reached deeper into muscles and activated the ink more precisely. It also prints at about 40 millimetres per second, similar to the speed of a regular inkjet printer.

Bioink Brings New Hope for Cancer Treatment?

In cancer models, the team had 3D printed a drug-releasing patch directly at the tumor site in mice, maintaining local delivery longer than existing methods.
They also printed artificial tissue deep under the skin in rabbits, showing the method works in larger animals.

The bioink can be customized with tiny materials like carbon nanotubes and nanoparticles to create sensors that monitor tissue activity, such as heart and muscle health. The ink stays good for at least 450 days and doesn’t trigger immune reactions. The body breaks down extra ink naturally, or it can be removed with a special treatment.

Challenges remain, like differences in tissue depth and printing on moving organs. AI could help by adjusting the printing process in real time for better results.

While more work is needed before clinical use, the team believes the technology has wide potential.

References:

1. Fan, Shelly. “Scientists Can Now 3D Print Tissues Directly Inside the Body—No Surgery Needed.” Singularity Hub, May 12, 2025. https://singularityhub.com/2025/05/12/scientists-can-now-3d-print-tissues-directly-inside-the-body-no-surgery-needed/.

2. GEN Staff. “In Vivo Bioprinting Shows Promise for 3D Printed Implants Without Surgery.” Genetic Engineering & Biotechnology News, May 8, 2025. https://www.genengnews.com/topics/translational-medicine/in-vivo-bioprinting-shows-promise-for-3d-printed-implants-without-surgery/.

(Input from various sources)

(Rehash/Tadikonda Ambica/MSM)