Acute middle ear infections affect more than 700 million people each year, with children often experiencing the most recurrent and severe symptoms due to their underdeveloped physiology. By the age of three, 25-40 % of children have had at least three episodes of acute middle ear infection, which is commonly accompanied by excess fluids accumulating behind the tympanic membrane (eardrum) and prolonged inflammation in the ear. Improper treatment of these infections can lead to high levels of pain, temporary or permanent hearing loss, and speech delay in children.
Recurrent ear infections and persistent fluid in the tympanic cavity are currently treated via the placement of tympanostomy tubes (commonly known as “ear tubes”) into the tympanic membrane that help equalize the pressure of and drain fluids from the middle ear. However, this approach suffers from frequent complications, including the progressive occlusion of the tympanostomy tubes’ lumen by cellular debris, pathogenic bacterial films, ear wax, blood and pus. Occlusion of ear tubes prevents proper ventilation and drainage of fluids out of the middle ear. Furthermore, due to the various materials and design limitations of conventional ear tubes, efficient delivery of antibiotic solutions into the middle ear is hindered. In the longer-term, a sub-optimal tympanostomy tube design can result in either premature extrusion or failure to self-extrude, requiring further replacement or removal surgeries that must be performed under general or local anesthesia and potentially leading to permanent damage to the tympanic membrane.
To address this challenge, a team of materials scientists at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS) led by Wyss Institute Core Faculty member Joanna Aizenberg, Ph.D., and Technology Development Fellow Ida Pavlichenko, Ph.D., who spearheaded the project in Aizenberg’s group, have developed a new type of customizable tympanostomy tube with rationally designed geometries fabricated using 3D printing and injection molding techniques.
By using proprietary liquid-infused medical-grade polymers that present a frictionless, antibiofouling lubricious layer, this next-generation tympanostomy tube dramatically reduces the adhesion of biofluids, as well as keratinocytes, fibroblasts, and common ear infection-causing bacterial strains by about 99% when compared with conventional tympanostomy tubes. Fluidic transport tests demonstrate a selective and controllable passage of water, antibiotic drops, and mucus through the lumen of the liquid-infused tympanostomy tubes that have dimensions similar to or even smaller than conventional tympanostomy tubes. These novel liquid-infused tympanostomy tubes will allow for a more effective resolution of infection and targeted drug delivery to treat a broad spectrum of ear and hearing disorders.
In collaboration with Dr. Aaron Remenschneider and Dr. Elliott Kozin at Massachusetts Eye and Ear, the team is currently performing highly promising preclinical studies in an established chinchilla model and is planning first-in-human clinical trials soon thereafter.