Researchers at Stanford University have developed a magnetic gel that coats kidney stone fragments, allowing for their removal in bulk using a magnetic wire. Tested successfully in pigs, the technique aims to reduce tissue damage and the need for repeated surgeries compared to standard methods. Experts praise it as a promising alternative to current procedures.
Kidney stones form when minerals in urine crystallize, causing pain when they lodge in the kidneys or ureters, the tubes connecting the kidneys to the bladder. Standard treatments involve breaking the stones into smaller pieces using a laser inserted through the bladder into the ureter and kidney, or by pulsing ultrasound waves from outside the body. Surgeons then typically remove these fragments one by one with a wire basket fed through the urethra, a process that can damage tissue and leaves fragments behind in about 40 percent of cases, increasing the risk of new stones forming.
To address these issues, Joseph Liao at Stanford University in California and his colleagues created a magnetic gel that coats stone fragments and a magnetic wire to capture them. Previously tested in a lab dish, the method was recently evaluated in four pigs. The team inserted dozens of human kidney stone fragments into the animals' kidneys and injected the magnetic gel into the organs. Using the magnetic wire passed through the urethra, they retrieved multiple fragments at once, unlike the single-piece limitation of wire baskets.
"It’s sort of like using a stick to fish out a scoop full of stone fragments, so you can remove a large amount of them in one go," says Liao. This approach minimizes insertions into the kidney, reducing tissue damage, and can capture fragments of any size, potentially clearing them completely and lowering the risk of further surgery.
Veronika Magdanz at the University of Waterloo in Canada, who was not involved, calls it "a very promising approach." She notes that "anything that increases the collection success of the stones and picks up more pieces at a time is helpful." None of the pigs showed side effects from the gel, which proved non-toxic. After further pig studies, the team plans human trials in about a year. The research appears in a journal with DOI: 10.1016/j.device.2025.100971.