Magnetic stem cell microrobots enable intervention in tiny, tortuous lumens

Researchers at the Chinese University of Hong Kong (CUHK) have developed magnetic stem cell spheroid microrobots (MSCSMs) that can be rapidly delivered with high precision to tiny and tortuous lumens, enabling targeted therapeutic intervention at sites inaccessible with conventional endoscopes and medical robots.

The MSCSMs, composed of stem cells (98.1 percent) and magnetic particles (1.9 percent), are soft and elastic with a modulus comparable with that of human brain tissue. “The MSCSMs are biocompatible and biodegradable. The stem cells can be harvested from the host to minimize immune responses during in vivo delivery,” said investigator Professor Li Zhang of the Department of Mechanical and Automation Engineering, CUHK. [Sci Robot 2021;doi:10.1126/scirobotics.abd2813] 

“With reconfigurable shape and high adaptability to the physiological environment to which they are applied, the MSCSMs can pass through channels that are narrower than their diameter of approximately 100–500 μm,” Zhang continued. “They can also be tracked in real time in vivo with the use of imaging techniques such as endoscopy and ultrasonography.”

Rapid endoluminal delivery of the MSCSMs to deep, narrow and tortuous lumens is made possible with an endoscopy-assisted magnetic actuation with dual imaging system (EMADIS).

“With EMADIS, the MSCSMs are deployed through an endoscope, which provides an ‘express lane’ for the microrobots to avoid direct contact with the complex fluidic environment and facilitate rapid passage through multiple biological barriers in organs or tissues,” explained Zhang. “Following endoscopic deployment, magnetic field actuation guides high-precision delivery of the MSCSMs under endoscopy and ultrasound imaging, enabling targeted therapeutic intervention inside tiny and tortuous lumens that are inaccessible and even invisible with the use of conventional endoscopes and medical robots.”

“The biohybrid microrobots can carry a large portion of stem cells for targeted therapy. They have enormous potential for future treatment of gastrointestinal diseases, such as common bile duct or intrahepatic duct stones, inflammatory bowel disease, and benign biliary strictures,” said Professor Philip Chiu of the CUHK Jockey Club Minimally Invasive Surgical Skills Centre.

“This technology extends the reach of endoscopy to human organ compartments that are inaccessible with conventional endoscopes, including smaller branches of the bile duct, the pancreatic duct, the bronchial tree, and smaller branches of the urinary system, such as renal calyces and the prostate,” said Professor Joseph Sung, CUHK Emeritus Professor of Medicine, and Dean of Lee Kong Chian School of Medicine and Senior Vice President (Health and Life Sciences) of Nanyang Technological University, Singapore. “With magnetic navigation, the biohybrid microrobots can offer new diagnostic and therapeutic opportunities. Animal studies to prove safety and clinical trials to validate efficacy are much awaited.”

The microrobots (red arrow) have a diameter of 100–500 µm each