Search Results (28)

Recent advances in enone chemistry have enabled the development of structurally optimized derivatives with improved anticancer selectivity. In this study, the cytotoxic activity and underlying mechanisms of sodium salts of four α,β-unsaturated enones (ES1–ES4), synthesized from vanillin-based scaffolds, were evaluated in human colorectal carcinoma (HCT-116), cervical adenocarcinoma (HeLa), and normal lung fibroblast (MRC-5) cell lines. All compounds exhibited concentration- and time-dependent cytotoxicity, with ES2 showing the highest potency (IC₅₀ = 14.25 μM in HCT-116 and 18.12 μM in HeLa at 72 h) and minimal toxicity toward MRC-5 cells (IC₅₀ > 90 μM). Although cisplatin demonstrated greater overall cytotoxicity, the enone salts displayed significantly higher selectivity indices, indicating a more favorable therapeutic window. Phase-contrast microscopy revealed characteristic morphological features of apoptosis, including cell rounding and membrane blebbing. Mechanistic investigations confirmed mitochondrial-mediated apoptosis, evidenced by increased early and late apoptotic populations, Bax upregulation, Bcl-2 downregulation, and caspase-3 activation. JC-10 staining demonstrated mitochondrial membrane depolarization accompanied by cytochrome c release. In addition, cell cycle analysis revealed pronounced G2/M phase arrest, particularly in HCT-116 cells. Collectively, these findings indicate that vanillin-derived enone sodium salts exert selective anticancer effects through mitochondrial apoptosis and cell cycle disruption, supporting their potential as low-toxicity anticancer candidates. Full article

Background/Objectives: Atraumatic electrode array insertion should be targeted in cochlear implantation. Robotic insertion is used in many centers worldwide. Our objective was to evaluate manual electrode placement and robot-assisted placement using RobOtol^® on human temporal bones (TBs), in terms of endocochlear trauma and completion of insertion. Methods: Sixteen TBs originating from eight bodies were implanted with Medel-FLEX24 electrodes through the round window. The right TB was implanted manually, while the left TB of the same body was implanted using RobOtol^® for electrode insertion. Results were analyzed through micro-computed tomography imaging. No statistical analysis was used, given the small sample size; a descriptive interpretation of micro-CT scans was rather preferred. Results: In the “manual group”, there were two cases (25%) of insertion trauma: elevation of basilar membrane at basal turn (Eshraghi-stage-1). In the “robotic group”, there were two cases (25%) of insertion trauma: one case of elevation of basilar membrane at the middle turn (Eshraghi-stage-1) and one case of dislocation of all electrodes in scala vestibuli (Eshraghi-stage-3). There were six cases (75%) of incomplete insertion in the “manual group” and four cases (50%) of incomplete insertion in the “robotic group”. Conclusions: Both techniques of electrode placement yielded fairly similar results, in terms of endocochlear trauma and completion of insertion. New larger-scale cadaveric and clinical studies are needed to determine the possible benefit of robot-assisted electrode insertion in cochlear implantation. Full article

Background/Objectives: To review the dimensions of the round window region (round window niche, bony structures surrounding the niche, and the membrane itself). Methods: Medline, EMBASE, Cochrane Library, and Google Scholar databases were searched by two independent reviewers. Anatomical and radiological studies on the round window region were screened. Studies reporting at least one dimension for the round window (RW) niche and/or the RW membrane were included. Results: Sixteen studies met the inclusion criteria (13 anatomical and 3 radiological studies) for a total number of 808 temporal bones with at least one dimension reported. The structures measured varied across the different studies with 12 reporting RW membrane dimensions (area and/or at least one distance), 8 detailing RW niche dimensions (height, width or depth) and 6 which measured at least one element of the RW bony overhangs (posterior or anterior pillar, RW tegmen). Surface area of the RW membrane varied between 0.32 mm² and 2.89 mm², with a minimum dimension (minimum diameter or height or width) comprising between 0.51 mm and 2.1 mm. When the bony overhangs surrounding the membrane were not considered, the minimum diameter was between 1.65 mm and 1.97 mm. Conclusions: The dimensions of the RW region are intrinsically variable, but the heterogeneity of the measurements reported also contributes to these variations. Posterior pillar, RW tegmen, anterior pillar, and their relative development probably account for a large part of this variability. The future RW membrane devices should be ≤1 mm in their maximum dimension, whether or not individually tailored, to fit most of the RW membranes. Full article

This study investigates the dynamic properties of the human middle ear and the energy transfer phenomena between the stapes footplate (SF) and the round window membrane (RWM) under sound stimulation. A series of laboratory tests were conducted, and a numerical model of the system was prepared. During the experiments, vibrations in human temporal bones were recorded using a Laser Doppler Vibrometer (LDV), and the frequency response functions (FRFs) of the RWM and SF footplate were computed. Key resonances were identified, with notable differences in vibration amplitude depending on whether the artificial external ear canal was left open or closed. To evaluate the amplification of acoustic waves within the cochlea, the authors proposed a novel index defined as the ratio of the FRF of the RWM and SF, respectively. The performed computations showed that signal amplification is particularly noticeable in the frequency range from 1 to 2 kHz. Subsequently, a simplified computational fluid dynamics (CFD) model of the cochlea was developed to simulate internal pressure distribution within the scala vestibuli (SV) and scala tympani (ST) spaces. The numerical computations of acoustic signal amplification showed good agreement with the experimental data, particularly at the frequencies of 1 and 2 kHz. These findings provide new insights into cochlear acoustics and offer a potential tool for evaluating pathological disorders and designing prosthetic devices. Full article

A virtual model of the rhesus macaque inner ear was created in the present study. Rhesus macaques have been valuable in cochlear research; however, their high cost prompts a need for alternative methods. Finite Element (FE) analysis offers a promising solution by enabling detailed simulations of the inner ear. This study employs FE analysis to create a virtual model of the rhesus macaque’s inner ear, reconstructed from MRI scans, to explore how cochlear implants (CIs) impact residual hearing loss. Harmonic-acoustic simulations of sound wave transmission indicate that CIs have minor effects on the displacement of the basilar membrane and thus minimally impact residual hearing loss post-implantation, but stiffening of the round window membrane worsens this effect. While the rhesus macaque FE model presented in this study shows some promise, its potential applications will require further validation through additional simulations and experimental studies. Full article

Background: Preserving residual hearing after cochlear implant (CI) surgery remains a crucial challenge. The application of dexamethasone (DEX) has been proven to positively affect residual hearing. To deliver DEX in a localized and controlled way, a round window niche implant (RNI), allowing drug diffusion via the round window membrane into the cochlea, may be used. To prove this concept, an RNI for guinea pigs as a CI-trauma model was manufactured by molding and tested for its drug release in vitro and biological effects in vivo. Methods: The RNIs were molded using silicone containing 10% DEX. Release was analyzed over time using high-performance liquid chromatography (HPLC). Fourteen adult guinea pigs were randomly assigned to two groups (CI or CI + RNI group). All animals received a unilateral CI electrode insertion trauma followed by CI insertion. The CI + RNI group was additionally implanted with an RNI containing 10% DEX. Animals were followed up for 4 weeks. Acoustically evoked auditory brainstem response and impedance measurement, micro-computed tomography (µCT) imaging, and histology were performed for evaluation. Results: DEX was released for more than 250 days in vitro, with an initial burst followed by a slower release over time. Comparing the hearing threshold shift (from day 0 to day 28) of the CI and CI + RNI groups, significant differences were observed at 32 and 40 kHz. The impedance shift at basal contacts was lower in the CI + RNI group than in the CI group. Moreover, the fibrosis in the lower basal turn was reduced in the CI + RNI group in contrast to the CI group. Conclusions: The RNI containing 10% DEX has anti-inflammatory potential concerning fibrosis inhibition and has beneficial effects on hearing preservation at high frequencies. Full article

Background: Cochlear implant (CI) electrode insertion can change the mechanical state of the ear whereby wideband tympanometry absorbance (WBTA) may serve as a sensitive tool to monitor these mechanical changes of the peripheral auditory pathway after CI surgery. In WBTA, the amount of acoustic energy reflected by the tympanic membrane is assessed over a wide frequency range from 226 Hz to 8000 Hz. The objective of this study was to monitor changes in WBTA in CI recipients before and after surgery. Methods: Following otoscopy, WBTA measurements were conducted twice in both ears of 38 standard CI recipients before and in the range of 4 to 15 weeks after CI implantation. Changes from pre- to postoperative absorbance patterns were compared for the implanted as well as the contralateral control ear for six different frequencies (500 Hz, 750 Hz, 1000 Hz, 2000 Hz, 3000 Hz, 4000 Hz). Furthermore, the influence of the time point of the measurement, surgical access, electrode type, sex and side of the implantation were assessed for the implanted and the control ear in a linear mixed model. Results: A significant decrease in WBTA could be observed in the implanted ear when compared with the contralateral control ear for 750 Hz (p < 0.01) and 1000 Hz (p < 0.05). The typical two-peak pattern of WBTA measurements was seen in both ears preoperatively but changed to a one-peak pattern in the newly implanted ear. The linear mixed model showed that not only the cochlear implantation in general but also the insertion through the round window compared to the cochleostomy leads to a decreased absorbance at 750 and 1000 Hz. Conclusions: With WBTA, we were able to detect mechanical changes of the acoustical pathway after CI surgery. The implantation of a CI led to decreased absorbance in the lower frequencies and the two-peak pattern was shifted to a one-peak pattern. The result of the linear mixed model indicates that WBTA can detect mechanical changes due to cochlear implantation not only in the middle ear but also in the inner ear. Full article

Background: Middle ear active implants, such as the Vibrant Soundbridge (VSB), offer an alternative to reconstructive surgery and other implantable hearing aid systems for patients with conductive, mixed, or sensorineural hearing loss. The primary objective of this work is to describe the auditory results obtained with VSB in our patient cohort, measuring the auditory gain in terms of average tonal thresholds and spoken word discrimination at 65 dB. Secondly, auditory gain differences between different types of hearing loss, coupling to the ossicular chain compared to round and oval windows, and the impact of open versus more conservative surgical approaches, were analyzed. Methods: A cross-sectional observational study, with retrospective data collection, was conducted at a tertiary care center. Clinical and audiometric data pre- and post-implantation were included, from patients who underwent VSB device placement surgery between 2001 and 2024. Results: 55 patients with an average age of 62.58 ± 17.83 years and a slight preference in terms of the female gender (52.72%) were included in the study. The average gain in the PTA for all types of hearing loss was 41.56 ± 22.63 dB, while for sensorineural hearing loss (SNHL) the gain was 31.04 ± 8.80 dB. For mixed-conductive hearing loss (C-MHL) a gain of 42.96 ± 17.70 was achieved, notably, in terms of absolute values, at frequencies of 4000 and 6000 Hz, with gains reaching 49.25 ± 20.26 dB at 4 K and 51.16 ± 17.48 dB at 6 K. In terms of spoken word discrimination, for all types of hearing loss, an improvement of 75.20 ± 10.11% was achieved. However, patients with C-MHL exhibited an approximately 13% higher gain compared to those with SNHL (69.32 ± 24.58% vs. 57.79 ± 15.28%). No significant differences in auditory gain were found between open and closed surgical techniques, nor in the proportion of adverse effects, when comparing one technique with the other. Conclusions: The VSB is effective in improving hearing in patients with mixed, conductive, and sensorineural hearing loss, with significant gains at high frequencies, especially through the round window membrane approach. The choice of surgical technique should consider the patient’s anatomical characteristics and specific needs in order to optimize auditory outcomes and minimize postoperative complications. Full article

A novel approach for the long-term medical treatment of the inner ear is the diffusion of drugs through the round window membrane from a patient-individualized, drug-eluting implant, which is inserted in the middle ear. In this study, drug-loaded (10 wt% Dexamethasone) guinea pig round window niche implants (GP-RNIs, ~1.30 mm × 0.95 mm × 0.60 mm) were manufactured with high precision via micro injection molding (µIM, T_mold = 160 °C, crosslinking time of 120 s). Each implant has a handle (~3.00 mm × 1.00 mm × 0.30 mm) that can be used to hold the implant. A medical-grade silicone elastomer was used as implant material. Molds for µIM were 3D printed from a commercially available resin (T_G = 84 °C) via a high-resolution DLP process (xy resolution of 32 µm, z resolution of 10 µm, 3D printing time of about 6 h). Drug release, biocompatibility, and bioefficacy of the GP-RNIs were investigated in vitro. GP-RNIs could be successfully produced. The wear of the molds due to thermal stress was observed. However, the molds are suitable for single use in the µIM process. About 10% of the drug load (8.2 ± 0.6 µg) was released after 6 weeks (medium: isotonic saline). The implants showed high biocompatibility over 28 days (lowest cell viability ~80%). Moreover, we found anti-inflammatory effects over 28 days in a TNF-α-reduction test. These results are promising for the development of long-term drug-releasing implants for human inner ear therapy. Full article

The aim of this study was to develop and validate a semi-automated segmentation approach that identifies the round window niche (RWN) and round window membrane (RWM) for use in the development of patient individualized round window niche implants (RNI) to treat inner ear disorders. Twenty cone beam computed tomography (CBCT) datasets of unilateral temporal bones of patients were included in the study. Defined anatomical landmarks such as the RWM were used to develop a customized 3D Slicer™ plugin for semi-automated segmentation of the RWN. Two otolaryngologists (User 1 and User 2) segmented the datasets manually and semi-automatically using the developed software. Both methods were compared in-silico regarding the resulting RWM area and RWN volume. Finally, the developed software was validated ex-vivo in N = 3 body donor implantation tests with additively manufactured RNI. The independently segmented temporal bones of the different Users showed a strong consistency in the volume of the RWN and the area of the RWM. The volume of the semi-automated RWN segmentations were 48 ± 11% smaller on average than the manual segmentations and the area of the RWM of the semi-automated segmentations was 21 ± 17% smaller on average than the manual segmentation. All additively manufactured implants, based on the semi-automated segmentation method could be implanted successfully in a pressure-tight fit into the RWN. The implants based on the manual segmentations failed to fit into the RWN and this suggests that the larger manual segmentations were over-segmentations. This study presents a semi-automated approach for segmenting the RWN and RWM in temporal bone CBCT scans that is efficient, fast, accurate, and not dependent on trained users. In addition, the manual segmentation, often positioned as the gold-standard, actually failed to pass the implantation validation. Full article

Sonoporation using microbubble-assisted ultrasound increases the permeability of a biological barrier to therapeutic molecules. Application of this method to the round window membrane could improve the delivery of therapeutics to the inner ear. The aim of this study was to assess the safety of sonoporation of the round window membrane in a sheep model. To achieve this objective, we assessed auditory function and cochlear heating, and analysed the metabolomics profiles of perilymph collected after sonoporation, comparing them with those of the control ear in the same animal. Six normal-hearing ewes were studied, with one sonoporation ear and one control ear for each. A mastoidectomy was performed on both ears. On the sonoporation side, Vevo MicroMarker^® microbubbles (MBs; VisualSonics—Fujifilm, Amsterdam, The Netherlands) at a concentration of 2 × 10⁸ MB/mL were locally injected into the middle ear and exposed to 1.1 MHz sinusoidal ultrasonic waves at 0.3 MPa negative peak pressure with 40% duty cycle and 100 μs interpulse period for 1 min; this was repeated three times with 1 min between applications. The sonoporation protocol did not induce any hearing impairment or toxic overheating compared with the control condition. The metabolomic analysis did not reveal any significant metabolic difference between perilymph samples from the sonoporation and control ears. The results suggest that sonoporation of the round window membrane does not cause damage to the inner ear in a sheep model. Full article

Advancements in intracochlear diagnostics, as well as prosthetic and regenerative inner ear therapies, rely on a good understanding of cochlear microanatomy. The human cochlea is very small and deeply embedded within the densest skull bone, making nondestructive visualization of its internal microstructures extremely challenging. Current imaging techniques used in clinical practice, such as MRI and CT, fall short in their resolution to visualize important intracochlear landmarks, and histological analysis of the cochlea cannot be performed on living patients without compromising their hearing. Recently, optical coherence tomography (OCT) has been shown to be a promising tool for nondestructive micrometer resolution imaging of the mammalian inner ear. Various studies performed on human cadaveric tissue and living animals demonstrated the ability of OCT to visualize important cochlear microstructures (scalae, organ of Corti, spiral ligament, and osseous spiral lamina) at micrometer resolution. However, the interpretation of human intracochlear OCT images is non-trivial for researchers and clinicians who are not yet familiar with this novel technology. In this study, we present an atlas of intracochlear OCT images, which were acquired in a series of 7 fresh and 10 fresh-frozen human cadaveric cochleae through the round window membrane and describe the qualitative characteristics of visualized intracochlear structures. Likewise, we describe several intracochlear abnormalities, which could be detected with OCT and are relevant for clinical practice. Full article

Inner ear gene therapy using adeno-associated viral vectors (AAVs) in neonatal mice can alleviate hearing loss in mouse models of deafness. However, efficient and safe transgene delivery to the adult mouse cochlea is critical for the effectiveness of AAV-mediated therapy. Here, we examined three gene delivery approaches including posterior semicircular canal (PSCC) canalostomy, round window membrane (RWM) injection, and tubing-RWM+PSCC (t-RP) in adult mice. Transduction rates and survival rates of cochlear hair cells were analyzed, hearing function was recorded, AAV distribution in the sagittal brain sections was evaluated, and cochlear histopathologic images were appraised. We found that an injection volume of 1 μL AAV through the PSCC is safe and highly efficient and does not impair hearing function in adult mice, but local injection allows AAV vectors to spread slightly into the brain. We then tested five AAV serotypes (PHP.eB, IE, Anc80L65, AAV2, and PHP.s) in parallel and observed the most robust eGFP expression in inner hair cells, outer hair cells, and spiral ganglion neurons throughout the cochlea after AAV-Anc80L65 injection. Thus, PSCC-injected Anc80L65 provides a foundation for gene therapy in the adult cochlea and will facilitate the development of inner ear gene therapy. Full article

Objectives: Precision medicine for inner ear disorders has seen significant advances in recent years. However, unreliable access to the inner ear has impeded diagnostics and therapeutic delivery. The purpose of this review is to describe the development, production, and utility of novel microneedles for intracochlear access. Methods: We summarize the current work on microneedles developed using two-photon polymerization (2PP) lithography for perforation of the round window membrane (RWM). We contextualize our findings with the existing literature in intracochlear diagnostics and delivery. Results: Two-photon polymerization lithography produces microneedles capable of perforating human and guinea pig RWMs without structural or functional damage. Solid microneedles may be used to perforate guinea pig RWMs in vivo with full reconstitution of the membrane in 48–72 h, and hollow microneedles may be used to aspirate perilymph or inject therapeutics into the inner ear. Microneedles produced with two-photon templated electrodeposition (2PTE) have greater strength and biocompatibility and may be used to perforate human RWMs. Conclusions: Microneedles produced with 2PP lithography and 2PTE can safely and reliably perforate the RWM for intracochlear access. This technology is groundbreaking and enabling in the field of inner ear precision medicine. Full article

Hearing loss and balance disorders are highly common disorders, and the development of effective oto-therapeutics remains an area of intense research. Drug development and screening in the hearing research field heavily rely on the use of preclinical models with often ambiguous translational relevance. This often leads to failed advancement in the market of effective therapeutics. In this context, especially for inner ear-specific pathologies, the availability of an in vitro, physiologically relevant, round window membrane (RWM) model could enable rapid, high-throughput screening of potential topical drugs for inner ear and cochlear dysfunctions and could help accelerate the advancement to clinic and market of more viable drug candidates. In this study, we report the development and evaluation of an in vitro model that mimics the native RWM tissue morphology and microenvironment as shown via immunostaining and histological analyses. The developed three-dimensional (3D) in vitro model was additionally assessed for barrier integrity by transepithelial electrical resistance, and the permeability of lipophilic and hydrophilic drugs was determined. Our collective findings suggest that this in vitro model could serve as a tool for rapid development and screening of topically deliverable oto-therapeutics. Full article