ASA Monitor July 2023, Vol. 87, 12–34.
Infused tympanostomy tubes for treatment of middle ear infections
Middle ear infections are extremely common and affect children especially, with 40% developing recurrent infections that can lead to complications like impaired hearing, speech and language delays, perforations in their eardrums, and life-threatening meningitis. “Tympanostomy tubes” (TTs) are surgically inserted into the eardrum to create an opening between the ear canal and middle ear, ventilate the middle ear, provide a route for fluid to drain out, and allow antibiotic drops to reach the infection-causing bacteria, as one form of treatment. The plastic or metal hollow cylindrical devices are imperfect treatments, however, as bacteria can lay down biofilms and local tissue can grow on their surfaces, which blocks TTs’ lumen and causes them to extrude, and antibiotic ear drops applied in the ear canal may not reach the site of infection anymore. Problems affecting TTs similarly affect other fluid-transporting “implantable medical conduits” (IMCs), such as catheters, shunts, and various small tubes with use in the brain, liver, eyes, and other organs where a high-pressure barrier prevents fluids from flowing through the conduit. To improve the devices, biomedical engineers look for ways to reduce IMC devices’ size and invasiveness without increasing their risk of becoming blocked and malfunctioning. Researchers have created a new design for IMCs with predictable and effective uni- and bi-directional fluid transport at the millimeter scale that resists various contaminations. Using infused tympanostomy tubes, they have optimized drug delivery into and drainage of fluids out of the middle ear, resistance against water crossing from the outside into the middle ear, as well as the prevention of bacterial and cell adhesion to tubes, by introducing a novel curved lumen geometry of the tube from materials with liquid-infused surfaces and 3D printing. When the iTT prototypes were animal-tested, they kept out environmental water, prevented infectious buildup, reduced scarring, and remained clear for aeration and pressure equalization. They also preserved hearing and enabled more easy and reliable dosing of antibiotic ear drops to the middle ear compared to conventional TTs.
Gold nanoparticles reduce side effects in cancer treatment
Researchers have developed a drug delivery system that uses gold nanoparticles to deliver drugs to tumors with precision while dramatically reducing the potential for systemic side effects. Many cancer drugs potent enough to kill tumors also cause unpleasant side effects for patients. The development of the treatment involves packing and sealing drugs into a porous gold nano-framework, then applying a hyaluronic acid coating on the outer surface of the nanoparticle to further seal the drug inside, resulting in a stable particle that releases the drugs when it binds to hyaluronic acid receptors on the surface of a lymphoma tumor. The drugs are delivered selectively, with minimal leakage into the bloodstream, so lower quantities of drugs can be used to treat a tumor reducing the risk of toxic side effects. The gold nanoparticles continue to circulate in the bloodstream much longer than free-floating drug molecules, meaning that patients who currently receive daily treatments might be able to switch to weekly or biweekly regimens. In animal trials, lymphoma tumors also responded better to the targeted drug delivery than to non-targeted treatments, suggesting that new treatment protocols could be developed to improve outcomes in human cancer patients. The nanoparticles can be loaded with drugs very quickly and efficiently using inexpensive and scalable chemical processes, offsetting the expense of using gold to deliver pharmaceuticals.
Transbronchial microwave ablation treats oligometastatic tumors
The first patient in North America has received treatment for oligometastatic (OML) tumors in the lung with Ethicon’s NEUWAVE™ FLEX Microwave Ablation System guided by the MONARCH® Platform. The company’s multicenter, single-arm study examines the safety and effectiveness of transbronchial microwave ablation on OML tumors. The lung is a common site for metastatic spread of solid organ cancers such as colorectal, kidney, and sarcoma. A subgroup of patients with solid organ cancers has residual tumors in the lung and other organs that do not resolve despite systemic treatments. This subgroup of patients is determined to have an intermediate state of advanced malignancy in the lung, or OML disease, for which managing physicians seek minimally invasive and lung-sparing therapies. The precision robotic-assisted bronchoscopy delivers targeted transbronchial microwave ablation for the treatment of metastatic tumors in the periphery of the lung. The company’s transbronchial microwave ablation technology is a minimally invasive option and received FDA clearance in July 2020.
Imaging probe investigates link between iron redox and Alzheimer’s
Researchers have developed a new imaging technique to expand upon evidence that iron in the brain may play a role in Alzheimer’s disease. The imaging probe has shown that there is an increase in iron redox in the same regions of the brain where the amyloid beta plaques associated with Alzheimer’s occur. Within the past decade, scientists discovered that ferroptosis leads to cell death and plays a key role in neurodegenerative diseases, such as Alzheimer’s. Researchers developed DNA-based fluorescent sensors that can detect two different forms of iron (Fe2+ and Fe3+) at the same time in cell cultures and in brain slices from mice genetically modified to mimic Alzheimer’s. This is the first imaging technique that can simultaneously detect both forms of iron in cells and tissue while also indicating their quantity and spatial distribution. Researchers using the imaging probe can change one parameter at a time to see if it changes the plaques or the oxidative states of iron. That ability could help them better understand why there is an increased ratio of Fe3+ to Fe2+ in the location of amyloid beta plaques and whether increased iron redox is involved in forming the plaques. If further research determines that iron redox changes cause cell death in Alzheimer’s patients, that information could provide a potential new strategy for development of a drug that changes the ratio of Fe3+ to Fe2+ to help protect brain cells.