RESUMO
OBJECTIVES: Oral or intratympanic corticosteroids are commonly used to treat sudden sensorineural hearing loss (SSHL), tinnitus, and Meniere disease. Direct intracochlear delivery has been proposed to overcome the variability in bioavailability and efficacy of systemic or middle ear delivery. In this study, we aim to characterize the physiologic consequences of microneedle-mediated direct intracochlear injection of dexamethasone through the round window membrane (RWM). METHODS: In Hartley guinea pigs (n = 5), a post-auricular incision followed by bullostomy was made to access the round window membrane. Using 100 µm diameter hollow microneedles, 1.0 µl of 10 mg/ml dexamethasone was injected through the RWM over 1 min. Compound action potential (CAP) and distortion product otoacoustic action emissions (DPOAE) were measured before perforation, at 1 h, and at 5 h following injection. CAP hearing thresholds were measured from 0.5 to 40 kHz, and DPOAE f2 frequencies ranged from 1.0 and 32 kHz. Repeated measures ANOVA followed by pairwise t-tests were used for statistical analysis. RESULTS: ANOVA identified significant CAP threshold shifts at four frequencies (4, 16, 36, and 40 kHz) and differences in DPOAE at 1 frequency (6 kHz). Paired t-tests revealed differences between the pre-perforation and 1 h time point. By 5 h post injection, both CAP hearing thresholds and DPOAE recover and are not significantly different from baseline thresholds. CONCLUSION: Direct intracochlear delivery of dexamethasone via microneedles results in temporary shifts in hearing thresholds that resolve by 5 hours, thus supporting microneedle technology for the treatment of inner ear disorders. LEVEL OF EVIDENCE: NA Laryngoscope, 134:388-392, 2024.
Assuntos
Perda Auditiva Neurossensorial , Doença de Meniere , Zumbido , Cobaias , Animais , Audição , DexametasonaRESUMO
HYPOTHESIS: Microneedle-mediated intracochlear injection of siRNA-Lipofectamine through the round window membrane (RWM) can be used to transfect cells within the cochlea. BACKGROUND: Our laboratory has developed 100-µm diameter hollow microneedles for intracochlear injection through the guinea pig RWM. In this study, we test the feasibility of microneedle-mediated injection of siRNA and Lipofectamine, a commonly used reagent with known cellular toxicity, through the RWM for cochlear transfection. METHODS: Fluorescently labeled scramble siRNA was diluted into Lipofectamine RNAiMax and OptiMEM. One microliter of 5 µM siRNA was injected through the RWM of Hartley guinea pigs at a rate of 1 µl/min (n = 22). In a control group, 1.0 µl of Lipofectamine, with no siRNA, was diluted into OptiMEM and injected in a similar fashion (n = 5). Hearing tests were performed before and either at 24 hours, 48 hours, or 5 days after injection. Afterward, animals were euthanized, and cochleae were harvested for imaging. Control cochleae were processed in parallel to untreated guinea pigs. RESULTS: Fluorescence, indicating successful transfection, was observed within the basal and middle turns of the cochlea with limited distribution in the apex at 24 and 48 hours. Signal was most intense in the organ of Corti, spiral ligament, and spiral ganglion. Little to no fluorescence was observed at 5 days post-injection. No significant changes in auditory brainstem response (ABR) were noted post-perforation at 5 days, suggesting that siRNA-Lipofectamine at low doses does not cause cochlear toxicity. CONCLUSIONS: Small volumes of siRNA and Lipofectamine can be effectively delivered to cochlear structures using microneedles, paving the way for atraumatic cochlear gene therapy.
RESUMO
The unique resource constraints, urgency, and virulence of the coronavirus disease 2019 pandemic has sparked immense innovation in the development of barrier devices to protect healthcare providers from infectious airborne particles generated by patients during airway management interventions. Of the existing devices, all have shortcomings which render them ineffective and impractical in out-of-hospital environments. Therefore, we propose a new design for such a device, along with a pragmatic evaluation of its efficacy. Must-have criteria for the device included: reduction of aerosol transmission by at least 90% as measured by pragmatic testing; construction from readily available, inexpensive materials; easy to clean; and compatibility with common EMS stretchers. The Patient Particle Containment Chamber (PPCC) consists of a standard shower liner draped over a modified octagonal PVC pipe frame and secured with binder clips. 3D printed sleeve portals were used to secure plastic sleeves to the shower liner wall. A weighted tube sealed the exterior base of the chamber with the contours of the patient's body and stretcher. Upon testing, the PPCC contained 99% of spray-paint particles sprayed over a 90s period. Overall, the PPCC provides a compact, affordable option that can be used in both the in-hospital and out-of-hospital environments.