Kidney stones afflict approximately one in nine individuals, causing intense pain and serious infections. With over 1.3 million emergency room visits and healthcare expenditures exceeding $5 billion annually in the United States, they pose a significant health burden. Small, hard-to-extract fragments are often left behind, risking natural elimination. While technologies like focused ultrasound, fragment adhesion with biopolymers, and negative pressure aspiration have been explored, they face limitations, especially with standard ureteroscope channel sizes.
Magnetizing Renal Calculus Fragments
A published study introduced the Magnetic System for Total Nephrolith Extraction, a system designed to enhance the efficiency of renal calculus fragment removal. In this system, the stones are coated with a magnetic hydrogel and retrieved using a magnetic guidewire compatible with standard ureteroscopes.
In vitro, laser-obtained renal calculus fragments were separated by size and coated with either ferumoxytol alone or combined with chitosan (Hydrogel CF). Treated fragments were then subjected to a magnetic wire for fragment removal assessment. Additional tests included scanning electron microscopy and cell culture with human urothelial cells to evaluate the cytotoxicity of the magnetic hydrogel components. The hydrogel and its components underwent safety and efficacy evaluations in in vitro studies, human tissue samples, and murine models to assess their impact on urothelium and antibacterial properties.
Safe Fragment Removal
The Hydrogel CF, composed of ferumoxytol and chitosan, demonstrated 100% effectiveness in eliminating all tested fragments, even those measuring up to 4 mm, across various stone compositions. Particle tracing simulations indicated that small-sized stones (1 and 3 mm) could be captured several millimeters away. Scanning electron microscopy confirmed the binding of ferumoxytol and Hydrogel CF to the surface of calcium oxalate stones.
The components of Hydrogel CF did not induce significant cytotoxicity on human urothelial cells, even after a 4-hour exposure. Moreover, live mouse studies showed that Hydrogel CF caused less bladder urothelium exfoliation compared with chitosan, and the urothelium returned to normal within 12 hours. In addition, these components exhibited antibacterial properties, inhibiting the growth of uropathogenic bacteria such as Escherichia coli and Proteus mirabilis, comparable to that of ciprofloxacin.
The ability to eliminate lithiasic fragments, the absence of significant urothelial toxicity, and antibacterial activity suggest that the use of magnetic hydrogel could be integrated into laser treatments for renal stones through ureteroscopy without immediate complications. The antibacterial properties could offer potential postoperative benefits while reducing procedural time. Further animal studies are underway to assess the safety of Hydrogel CF before proceeding to human clinical trials.
This article was translated from JIM, which is part of the Medscape Professional Network. A version of this article appeared on Medscape.com.