Temporal Development of Depression and Anxiety in a Large Facial Palsy Cohort.

INTRODUCTION: Diagnosis with facial palsy (FP) has been linked to increased psychosocial distress and communication disorders, but limited data exist on the temporal development of depression and anxiety after diagnosis. In a large cohort of FP patients, we characterize the rates of depression and anxiety at several timepoints post-FP diagnosis. METHODS: A de-identified database of all FP patients who presented to a single healthcare system over 22 years was created using Epic SlicerDicer. Demographics and comorbidities were collected and depression and anxiety diagnosis rates at three timepoints (non-inclusive lower bounds) post-FP diagnosis were examined. RESULTS: 3,910 FP patients were identified, with a median age of 59. 56% were female and 51% were white. At 0-6, 6-12-, and 12-36-month post-FP diagnosis, 156 (4%), 58 (1.4%), and 205 (5.2%) individuals were diagnosed with depression, and 171 (4.4%), 84 (2.1%), and 237 (6.1%) were diagnosed with anxiety. At each time point, the median time between FP and depression diagnosis (2.1, 3.4, and 11.4 months) or anxiety diagnosis (2.5, 4.0, and 11.1 months) was similar. Dual depression and anxiety diagnoses were observed in 52 (1.3%), 32 (0.8%), and 122 (3.1%) patients at each time point. Compared to the overall cohort, more patients with anxiety were female (65 vs. 56%, p < 0.001) and younger (57 vs. 59, p = 0.002), and more depressed patients were Black (7.3 vs. 3.3%, p = 0.02). CONCLUSIONS: Facial palsy may lead to increased risk of depression and/or anxiety in the first year after diagnosis as demonstrated here in one of the largest FP cohorts to date. We report high rates of depression (5.5%), anxiety (6.5%), and comorbid depression and anxiety (2.1%) occurring within 1 year after FP diagnosis. Of these, the majority occurred within the first 6 months (72%, 67%, 62%, respectively). Anxiety was more common in young female patients and depression more common in Black patients, which can inform targeted mental health resources within the first 6 months post-FP diagnosis.

Tuning the Mechanical Properties of Multiarm RAFT-Based Block Copolyelectrolyte Hydrogels via Ionic Cross-Linking for 3D Cell Cultures.

Hydrogels that serve as native extracellular matrix (ECM) mimics are typically naturally derived hydrogels that are physically cross-linked via ionic interactions. This means rapid gelation of synthetic polymers, which give control over the chemical and physical cues in hydrogel formation. Herein, we combine the best of both systems by developing a synthetic hydrogel with ionic cross-linking of block copolyelectrolytes to rapidly create hydrogels. Reversible addition-fragmentation chain-transfer (RAFT) polymerization was used to synthesize oppositely charged polyelectrolyte molecules and, in turn, modulate the mechanical property of stiffness. The mechanical stiffness of a range of 900-3500 Pa was tuned by varying the number of charged ionic groups, the length of the polymer arms, and the polymer concentration. We demonstrate the synthetic polyelectrolyte hydrogel as an ECM mimic for three-dimensional (3D) in vitro cell models using MCF-7 breast cancer cells.

Cheek Donor Site for Full-Thickness Skin Graft Repair of the Nasal Ala: Outcomes of a Retrospective Cohort Study.

BACKGROUND: Full-thickness skin grafts (FTSGs) are useful repairs for reconstructing nasal alar defects. Traditional donor sites include the preauricular, postauricular, and supraclavicular skin. OBJECTIVE: To evaluate esthetic outcomes and complications of nasal alar defects repaired with FTSGs from the medial cheek. MATERIALS AND METHODS: A retrospective chart review of Mohs surgery patients who had FTSG repair of the nasal ala between January 2015 and August 2020 was performed. Demographic, surgery, and follow-up visit data were reviewed. Cosmesis was rated by a facial plastic surgeon, a Mohs surgeon, and a plastic surgeon using baseline, defect, and follow-up visit photographs. RESULTS: Sixty-nine patients with FTSG repairs of nasal alar defects were identified. 51 of 69 patients (73.9%) had the cheek donor site, and 18 of 69 patients (26.1%) had a noncheek donor site. The mean (SD) rater visual analog score for both cohorts was good with no significant difference (cheek: 65.9 [13.8]; noncheek: 66.1 [15.3]; p = .96). A notable difference in the complication rate by donor site was observed (cheek: 6.9%, noncheek: 16.7%; p = .13), although it did not reach significance. CONCLUSION: The cheek is a reliable FTSG donor site for nasal alar defects after Mohs micrographic surgery, with a trend toward fewer complications.

Effect of polar amino acid incorporation on Fmoc-diphenylalanine-based tetrapeptides.

Peptide hydrogels show great promise as extracellular matrix mimics due to their tuneable, fibrous nature. Through incorporation of polar cationic, polar anionic or polar neutral amino acids into the Fmoc-diphenylalanine motif, we show that electrostatic charge plays a key role in the properties of the subsequent gelators. Specifically, we show that an inverse relationship exists for biocompatibility in the solution state versus the gel state for cationic and anionic peptides. Finally, we use tethered bilayer lipid membrane (tBLM) experiments to suggest a likely mode of cytotoxicity for tetrapeptides which exhibit cytotoxicity in the solution state.

Association of Single and Dual Sensory Impairment with Falls among Medicare Beneficiaries.

Objective: The purpose of this study was to determine if dual sensory impairment (DSI) is associated with falls and fear of falling among older adults. Methods: Using data from the 2019 Medicare Current Beneficiary Survey (MCBS), we studied the cross-sectional association of self-reported hearing/vision impairment with self-reported history/number of falls over the past year, fear of falling (scale 1-6), and a fall requiring medical help using weighted multivariable regressions adjusted for demographic and clinical covariates. Results: Among 11,089 Medicare beneficiaries (mean age = 74, 55% female, 9% Black), DSI is associated with increased prevalence (prevalence ratio = 1.45 [1.28-1.65]) and incidence (incidence ratio = 2.21 [1.79-2.75]) rate of falls, and greater odds of a higher fear of falling score (odds ratio = 1.38 [1.08-1.77]). Discussion: DSI is associated with falls among older adults. Consideration of DSI as a marker to initiate fall prevention programs and inclusion of sensory interventions in these programs may be valuable.

The Rate of Occult Lesion Diagnosis in a Large Bell's Palsy Cohort.

OBJECTIVES: We characterize occult lesion diagnosis rates after initial Bell's palsy diagnoses. METHODS: A de-identified database of all facial palsy patients who presented to an extensive health care system across 22 years was created using Epic SlicerDicer. Among patients with Bell's palsy diagnoses, we extracted demographic and any subsequent occult lesion diagnosis data across various clinical sites. Descriptive and multivariable regression analyses comparing patients with occult lesion diagnoses made at different time points were included. RESULTS: Among the total 3912 facial palsy patients, 2240 had Bell's palsy diagnoses, of which 217 (9.7%) had subsequent lesion diagnoses at a median (IQR) of 12.3 (4.2, 23.8) months, consisting of cranial nerve neoplasms (62.2%), parotid gland neoplasms (34.1%), and cholesteatomas (3.7%). Although a large proportion of total lesions were diagnosed within the first 3 months (19.8%), 69.5% were diagnosed after 6 months. There were no demographic differences among patients diagnosed with different lesion types, but Asian patients were more likely to be diagnosed with occult lesions after 12 months after Bell's palsy diagnosis compared with white patients (odds ratio = 6.2, p = 0.001). CONCLUSIONS: In one of the largest Bell's palsy cohorts to date, we identified a 9.7% occult lesion diagnosis rate at a median of 12.3 months after Bell's palsy diagnosis. These data underscore the importance of timely workup for occult lesions in cases of facial palsy with no signs of recovery after 3-4 months. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:911-918, 2024.

Genome-wide association study for age-related hearing loss in CFW mice.

Age-related hearing impairment is the most common cause of hearing loss and is one of the most prevalent conditions affecting the elderly globally. It is influenced by a combination of environmental and genetic factors. The mouse and human inner ears are functionally and genetically homologous. Investigating the genetic basis of age-related hearing loss (ARHL) in an outbred mouse model may lead to a better understanding of the molecular mechanisms of this condition. We used Carworth Farms White (CFW) outbred mice, because they are genetically diverse and exhibit variation in the onset and severity of ARHL. The goal of this study was to identify genetic loci involved in regulating ARHL. Hearing at a range of frequencies was measured using Auditory Brainstem Response (ABR) thresholds in 946 male and female CFW mice at the age of 1, 6, and 10 months. We obtained genotypes at 4.18 million single nucleotide polymorphisms (SNP) using low-coverage (mean coverage 0.27x) whole-genome sequencing followed by imputation using STITCH. To determine the accuracy of the genotypes we sequenced 8 samples at >30x coverage and used calls from those samples to estimate the discordance rate, which was 0.45%. We performed genetic analysis for the ABR thresholds for each frequency at each age, and for the time of onset of deafness for each frequency. The SNP heritability ranged from 0 to 42% for different traits. Genome-wide association analysis identified several regions associated with ARHL that contained potential candidate genes, including Dnah11, Rapgef5, Cpne4, Prkag2, and Nek11. We confirmed, using functional study, that Prkag2 deficiency causes age-related hearing loss at high frequency in mice; this makes Prkag2 a candidate gene for further studies. This work helps to identify genetic risk factors for ARHL and to define novel therapeutic targets for the treatment and prevention of ARHL.

Electrostatically Cross-Linked Bioinks for Jetting-Based Bioprinting of 3D Cell Cultures.

It has been acknowledged that thousands of drugs that passed two-dimensional (2D) cell culture models and animal studies often fail when entering human clinical trials. Despite the significant development of three-dimensional (3D) models, developing a high-throughput model that can be reproducible on a scale remains challenging. One of the main challenges is precise cell deposition and the formation of a controllable number of spheroids to achieve more reproducible results for drug discovery and treatment applications. Furthermore, when transitioning from manually generated structures to 3D bioprinted structures, the choice of material is limited due to restrictions on materials that are applicable with bioprinters. Herein, we have shown the capability of a fast-cross-linking bioink that can be used to create a single spheroid with varying diameters (660, 1100, and 1340 µm) in a high-throughput manner using a commercialized drop-on-demand bioprinter. Throughout this work, we evaluate the physical properties of printable ink with and without cells, printing optimization, cytocompatibility, cell sedimentation, and homogeneity in ink during the printing process. This work showcases the importance of ink characterization to determine printability and precise cell deposition. The knowledge gained from this work will accelerate the development of next-generation inks compatible with a drop-on-demand 3D bioprinter for various applications such as precision models to mimic diseases, toxicity tests, and the drug development process.

Mitochondrial Interaction with Serotonin in Neurobiology and Its Implication in Alzheimer's Disease.

Alzheimer's disease (AD) is a lethal neurodegenerative disorder characterized by severe brain pathologies and progressive cognitive decline. While the exact cause of this disease remains unknown, emerging evidence suggests that dysregulation of neurotransmitters contributes to the development of AD pathology and symptoms. Serotonin, a critical neurotransmitter in the brain, plays a pivotal role in regulating various brain processes and is implicated in neurological and psychiatric disorders, including AD. Recent studies have shed light on the interplay between mitochondrial function and serotonin regulation in brain physiology. In AD, there is a deficiency of serotonin, along with impairments in mitochondrial function, particularly in serotoninergic neurons. Additionally, altered activity of mitochondrial enzymes, such as monoamine oxidase, may contribute to serotonin dysregulation in AD. Understanding the intricate relationship between mitochondria and serotonin provides valuable insights into the underlying mechanisms of AD and identifies potential therapeutic targets to restore serotonin homeostasis and alleviate AD symptoms. This review summarizes the recent advancements in unraveling the connection between brain mitochondria and serotonin, emphasizing their significance in AD pathogenesis and underscoring the importance of further research in this area. Elucidating the role of mitochondria in serotonin dysfunction will promote the development of therapeutic strategies for the treatment and prevention of this neurodegenerative disorder.

Epidemiology and Prognostic Indicators of Survival in Tongue Lymphoma.

OBJECTIVES: Lymphoma, categorized as either non-Hodgkin's lymphoma or Hodgkin's lymphoma, is the second most common malignancy in the head and neck. Primary tongue lymphoma is exceedingly rare, with only case reports or small case series in the literature. This population-based analysis is the first to report the epidemiology and prognostic factors of survival in patients with primary tongue lymphoma. METHODS: The Surveillance, Epidemiology, and End Results 18 database from the National Cancer Institute was queried for patients diagnosed between the years 2000 and 2016 with tongue lymphoma. Outcomes of interest were overall and disease-specific survival. Independent variables included age at diagnosis, sex, race, marital status, primary subsite, histologic subtype, stage, and treatment type. RESULTS AND CONCLUSION: Seven hundred forty patients met criteria; the male-female ratio was 1.5:1 and the mean age at diagnosis was 67.8 years. The majority of lesions localized to the base of tongue (90.0%), were histologically diffuse large B-cell lymphoma (59.5%), and presented at stage I or II (77.9%). Most early-stage lymphomas were treated with chemotherapy only (40.5%) or a combination of both chemotherapy and radiation (31.3%), while late-stage cancers were primarily treated with chemotherapy alone (68.5%). In multivariate analysis, younger age at diagnosis, female sex, married/partnered marital status, mucosa-associated lymphoid tissue histologic subtype, and earlier cancer stage were found to be associated with improved survival. Chemotherapy treatment with or without radiation was also associated with better survival compared to no treatment or radiation alone, though data regarding immunotherapy was unavailable.

Elevated Ghrelin Promotes Hippocampal Ghrelin Receptor Defects in Humanized Amyloid-ß Knockin Mice During Aging.

BACKGROUND: Emerging evidence has revealed that dysregulation of the hormone ghrelin and its receptor, growth hormone secretagogue receptor (GHSR), contributes to the pathogenesis of Alzheimer's disease (AD). Specifically, defective GHSR function and resultant hippocampal ghrelin resistance are linked to hippocampal synaptic injury in AD paradigms. Also, AD patients exhibit elevated ghrelin activation. However, the detailed molecular mechanisms of hippocampal GHSR dysfunction and the relevance of ghrelin elevation to hippocampal ghrelin resistance in AD-relevant pathological settings are not fully understood. OBJECTIVE: In the current study, we employed a recently established mouse line of AD risk [humanized amyloid beta knockin (hAß KI mice), also referred to as a mouse model of late-onset AD in previous literature] to further define the role of ghrelin system dysregulation in the development of AD. METHODS: We employed multidisciplinary techniques to determine the change of plasma ghrelin and the functional status of GHSR in hAß KI mice as well as primary neuron cultures. RESULTS: We observed concurrent plasma ghrelin elevation and hippocampal GHSR desensitization with disease progression. Further examination excluded the possibility that ghrelin elevation is a compensatory change in response to GHSR dysfunction. In contrast, further in vitro and in vivo results show that agonist-mediated overstimulation potentiates GHSR desensitization through enhanced GHSR internalization. CONCLUSIONS: These findings suggest that circulating ghrelin elevation is a pathological event underlying hippocampal GHSR dysfunction, culminating in hippocampal ghrelin resistance and resultant synaptic injury in late-onset AD-related settings.

Hearing Impairment and Allostatic Load in Older Adults.

Importance: Allostatic load, the cumulative strain that results from the chronic stress response, is associated with poor health outcomes. Increased cognitive load and impaired communication associated with hearing loss could potentially be associated with higher allostatic load, but few studies to date have quantified this association. Objective: To investigate if audiometric hearing loss is associated with allostatic load and evaluate if the association varies by demographic factors. Design, Setting, Participants: This cross-sectional survey used nationally representative data from the National Health and Nutrition Examination Survey. Audiometric testing was conducted from 2003 to 2004 (ages 20-69 years) and 2009 to 2010 (70 years or older). The study was restricted to participants aged 50 years or older, and the analysis was stratified based on cycle. The data were analyzed between October 2021 and October 2022. Exposure: A 4-frequency (0.5-4.0 kHz) pure tone average was calculated in the better-hearing ear and modeled continuously and categorically (<25 dB hearing level [dB HL], no hearing loss; 26-40 dB HL, mild hearing loss; ≥41 dB HL, moderate or greater hearing loss). Main Outcome and Measures: Allostatic load score (ALS) was defined using laboratory measurements of 8 biomarkers (systolic/diastolic blood pressure, body mass index [calculated as weight in kilograms divided by height in meters squared], and total serum and high-density lipoprotein cholesterol, glycohemoglobin, albumin, and C-reactive protein levels). Each biomarker was assigned a point if it was in the highest risk quartile based on statistical distribution and then summed to yield the ALS (range, 0-8). Linear regression models adjusted for demographic and clinical covariates. Sensitivity analysis included using clinical cut points for ALS and subgroup stratification. Results: In 1412 participants (mean [SD] age, 59.7 [5.9] years; 293 women [51.9%]; 130 [23.0%] Hispanic, 89 [15.8%] non-Hispanic Black, and 318 [55.3%] non-Hispanic White individuals), a modest association was suggested between hearing loss and ALS (ages 50-69 years: ß = 0.19 [95% CI, 0.02-0.36] per 10 dB HL; 70 years or older: ß = 0.10 [95% CI, 0.02-0.18] per 10 dB HL) among non-hearing aid users. Results were not clearly reflected in the sensitivity analysis with clinical cut points for ALS or modeling hearing loss categorically. Sex-based stratifications identified a stronger association among male individuals (men 70 years or older: ß = 0.22 [95% CI, 0.12-0.32] per 10 dB HL; women: ß = 0.08 [95% CI, -0.04 to 0.20] per 10 dB HL). Conclusion and Relevance: The study findings did not clearly support an association between hearing loss and ALS. While hearing loss has been shown to be associated with increased risk for numerous health comorbidities, its association with the chronic stress response and allostasis may be less than that of other health conditions.

Socioeconomic Disparities in the Pursuit of Care at a High-Volume Institution for Surgical Resection of Vestibular Schwannomas.

OBJECTIVE: Increased institutional surgical resection case volume for vestibular schwannomas (VSs) has been associated with improved patient outcomes, including reduced risk of prolonged hospital stay and readmission. Socioeconomic disparities in the pursuit of care at these high-volume institutions remain unknown. STUDY DESIGN: Retrospective cohort epidemiological study. SETTING: National Cancer Database, a hospital-based registry of over 1,500 facilities in the United States. PATIENTS: Adult VS patients (age, >18 years) treated surgically. INTERVENTIONS: High- versus low-volume facilities, defined using a facility case volume threshold of 25 cases per year. A risk-adjusted restricted cubic spline model was previously used to identify this risk threshold beyond which the incremental benefit of increasing case volume began to plateau. MAIN OUTCOME MEASURES: Sociodemographic factors, including race, ethnicity, income, insurance status, and rurality. Multivariable analyses were adjusted for patient and tumor characteristics, including age, sex, Charlson-Deyo score, and tumor size. RESULTS: A totoal of 10,048 patients were identified (median [interquartile range] age = 51 [41-60] years, 54% female, 87% Caucasian). Patients with Spanish/Hispanic ethnicity (OR = 0.71, 95% confidence interval [CI] = 0.52-0.96), income below median (OR = 0.63, 95% CI = 0.55-0.73]), and Medicare, Medicaid, or other government insurance versus private insurance (OR = 0.63, 95% CI = 0.53-0.74) had reduced odds of treatment at a high-volume facility. Further sensitivity analyses in which facility volume was operationalized continuously reinforced direction and significance of these associations. CONCLUSIONS: Socioeconomic disparities exist in the propensity for VS patients to be treated at a high-volume facility. Further work is needed to understand the nature of these associations and whether interventions can be designed to mitigate them.

Cochlear transcriptome analysis of an outbred mouse population (CFW).

Age-related hearing loss (ARHL) is the most common cause of hearing loss and one of the most prevalent conditions affecting the elderly worldwide. Despite evidence from our lab and others about its polygenic nature, little is known about the specific genes, cell types, and pathways involved in ARHL, impeding the development of therapeutic interventions. In this manuscript, we describe, for the first time, the complete cell-type specific transcriptome of the aging mouse cochlea using snRNA-seq in an outbred mouse model in relation to auditory threshold variation. Cochlear cell types were identified using unsupervised clustering and annotated via a three-tiered approach-first by linking to expression of known marker genes, then using the NSForest algorithm to select minimum cluster-specific marker genes and reduce dimensional feature space for statistical comparison of our clusters with existing publicly-available data sets on the gEAR website, and finally, by validating and refining the annotations using Multiplexed Error Robust Fluorescence In Situ Hybridization (MERFISH) and the cluster-specific marker genes as probes. We report on 60 unique cell-types expanding the number of defined cochlear cell types by more than two times. Importantly, we show significant specific cell type increases and decreases associated with loss of hearing acuity implicating specific subsets of hair cell subtypes, ganglion cell subtypes, and cell subtypes within the stria vascularis in this model of ARHL. These results provide a view into the cellular and molecular mechanisms responsible for age-related hearing loss and pathways for therapeutic targeting.

Factors Shifting Preference Toward Telemedicine in the Delivery of Skin Cancer Reconstruction Care.

OBJECTIVES: Identify which delivery modality for skin reconstruction care, face-to-face (FTF) in-person versus two telemedicine modalities, store-and-forward (S&F) and live video chat (LVC), is patient preferred and how cost, access, wait time, and demographics influence this preference. STUDY DESIGN: Cross-sectional survey. METHODS: A 16-question survey querying demographics and five scenario-specific preferences questions for the delivery of skin cancer reconstruction care was created and distributed via Amazon Mechanical Turk (MTurk), a crowdsourcing online marketplace, and in-person to Mohs micrographic surgery patients. RESULTS: 1394 MTurk and 55 in-person responses were included. While 82.1% of online respondents prefer FTF clinic visits, this decreases to 58.3% with an in-person visit cost (p < 0.01) and furthermore to a minority 43.5% with both an in-person visit cost and wait time (p < 0.01) despite 77.8% believing that usefulness to the surgeon would improve FTF. Both the MTurk and in-person cohorts demonstrated similar response patterns despite considerable demographic differences. Multivariable analyses revealed that telemedicine was preferred by MTurk respondents with Medicaid (adjusted OR [95% CI]: 1.97 [1.18-3.31]) or Medicare (1.69 [1.10-2.59]) versus private insurance, and prior skin cancer (2.01 [1.18-3.42]) and less preferred by those earning $140,000+ per year (0.49 [0.29-0.82]) compared to those earning <$20,000 per year. CONCLUSIONS: FTF visits are preferred for skin cancer reconstruction care; this shifts toward virtual care with a cost and wait time in spite of the perceived quality of care. Individuals with socioeconomic barriers to access prefer telemedicine. MTurk can be a valuable tool for behavioral research in FPRS. LEVEL OF EVIDENCE: NA Laryngoscope, 133:294-301, 2023.

Cochlear transcriptome analysis of an outbred mouse population (CFW).

Age-related hearing loss (ARHL) is the most common cause of hearing loss and one of the most prevalent conditions affecting the elderly worldwide. Despite evidence from our lab and others about its polygenic nature, little is known about the specific genes, cell types and pathways involved in ARHL, impeding the development of therapeutic interventions. In this manuscript, we describe, for the first time, the complete cell-type specific transcriptome of the aging mouse cochlea using snRNA-seq in an outbred mouse model in relation to auditory threshold variation. Cochlear cell types were identified using unsupervised clustering and annotated via a three-tiered approach - first by linking to expression of known marker genes, then using the NS-Forest algorithm to select minimum cluster-specific marker genes and reduce dimensional feature space for statistical comparison of our clusters with existing publicly-available data sets on the gEAR website (https://umgear.org/), and finally, by validating and refining the annotations using Multiplexed Error Robust Fluorescence In Situ Hybridization (MERFISH) and the cluster-specific marker genes as probes. We report on 60 unique cell-types expanding the number of defined cochlear cell types by more than two times. Importantly, we show significant specific cell type increases and decreases associated with loss of hearing acuity implicating specific subsets of hair cell subtypes, ganglion cell subtypes, and cell subtypes withing the stria vascularis in this model of ARHL. These results provide a view into the cellular and molecular mechanisms responsible for age-related hearing loss and pathways for therapeutic targeting.

Electrostatic Assembly of Multiarm PEG-Based Hydrogels as Extracellular Matrix Mimics: Cell Response in the Presence and Absence of RGD Cell Adhesive Ligands.

Synthetic hydrogels have been used widely as extracellular matrix (ECM) mimics due to the ability to control and mimic physical and biochemical cues observed in natural ECM proteins such as collagen, laminin, and fibronectin. Most synthetic hydrogels are formed via covalent bonding resulting in slow gelation which is incompatible with drop-on-demand 3D bioprinting of cells and injectable hydrogels for therapeutic delivery. Herein, we developed an electrostatically crosslinked PEG-based hydrogel system for creating high-throughput 3D in vitro models using synthetic hydrogels to mimic the ECM cancer environment. A 3-arm PEG-based polymer backbone was first modified with either permanent cationic charged moieties (2-(methacryloyloxy)ethyl trimethylammonium) or permanent anionic charged moieties (3-sulfopropyl methacrylate potassium salt). The resulting charged polymers can be conjugated further with various amounts of cell adhesive RGD motifs (0, 25, 75, and 98%) to study the influences of RGD motifs on breast cancer (MCF-7) spheroid formation. Formation, stability, and mechanical properties of hydrogels were tested with, and without, RGD to evaluate the cellular response to material parameters in a 3D environment. The hydrogels can be degraded in the presence of salts at room temperature by breaking the interaction of oppositely charged polymer chains. MCF-7 cells could be released with high viability through brief exposure to NaCl solution. Flow cytometry characterization demonstrated that embedded MCF-7 cells proliferate better in a softer (60 Pa) 3D hydrogel environment compared to those that are stiffer (1160 Pa). As the stiffness increases, the RGD motif plays a role in promoting cell proliferation in the stiffer hydrogel. Flow cytometry characterization demonstrated that embedded MCF-7 cells proliferate better in a softer (60 Pa) 3D hydrogel environment compared to those that are stiffer (1160 Pa). As the stiffness increases, the RGD motif plays a role in promoting cell proliferation in the stiffer hydrogel. Additionally, cell viability was not impacted by the tested hydrogel stiffness range between 60 to 1160 Pa. Taken together, this PEG-based tuneable hydrogel system shows great promise as a 3D ECM mimic of cancer extracellular environments with controllable biophysical and biochemical properties. The ease of gelation and dissolution through salt concentration provides a way to quickly harvest cells for further analysis at any given time of interest without compromising cell viability.

3D Bioprintable Hydrogel with Tunable Stiffness for Exploring Cells Encapsulated in Matrices of Differing Stiffnesses.

In vitro cell models have undergone a shift from 2D models on glass slides to 3D models that better reflect the native 3D microenvironment. 3D bioprinting promises to progress the field by allowing the high-throughput production of reproducible cell-laden structures with high fidelity. The current stiffness range of printable matrices surrounding the cells that mimic the extracellular matrix environment remains limited. The work presented herein aims to expand the range of stiffnesses by utilizing a four-armed polyethylene glycol with maleimide-functionalized arms. The complementary cross-linkers comprised a matrix metalloprotease-degradable peptide and a four-armed thiolated polymer which were adjusted in ratio to tune the stiffness. The modularity of this system allows for a simple method of controlling stiffness and the addition of biological motifs. The application of this system in drop-on-demand printing is validated using MCF-7 cells, which were monitored for viability and proliferation. This study shows the potential of this system for the high-throughput investigation of the effects of stiffness and biological motif compositions in relation to cell behaviors.

Genetics of noise-induced hearing loss in the mouse model.

Hearing loss is the most common sensory deficit worldwide, with the majority of preventable injury attributed to noise-induced hearing loss (NIHL). Highly conserved cochlear genetics between humans and mice have made this animal model a high-yield candidate for better characterizing the biologic and genetic underpinnings of human NIHL. This review aims to summarize advances in understanding the genetics of noise-induced hearing loss in mouse models dating from the early 1990s. We review the genetic mechanisms underpinning NIHL as understood in the mouse model, including histopathological and phenotypic associations, molecular and cellular mechanisms of changes in cochlear structures, synaptopathy and neuropathy, and transcriptomics. We describe variations in pathophysiology of hearing loss between mouse strains, with particular emphasis on susceptibility of different strains to different mechanisms of damage after acoustic trauma, and the potential of novel targeted therapeutic approaches for NIHL based on understanding of genetic mechanisms. Finally, we review the current state of research on the cochlear transcriptome after noise exposure in the mouse and implications for translation of these findings to humans.

Advances in 3D Bioprinting for Cancer Biology and Precision Medicine: From Matrix Design to Application.

The tumor microenvironment is highly complex owing to its heterogeneous composition and dynamic nature. This makes tumors difficult to replicate using traditional 2D cell culture models that are frequently used for studying tumor biology and drug screening. This often leads to poor translation of results between in vitro and in vivo and is reflected in the extremely low success rates of new candidate drugs delivered to the clinic. Therefore, there has been intense interest in developing 3D tumor models in the laboratory that are representative of the in vivo tumor microenvironment and patient samples. 3D bioprinting is an emerging technology that enables the biofabrication of structures with the virtue of providing accurate control over distribution of cells, biological molecules, and matrix scaffolding. This technology has the potential to bridge the gap between in vitro and in vivo by closely recapitulating the tumor microenvironment. Here, a brief overview of the tumor microenvironment is provided and key considerations in biofabrication of tumor models are discussed. Bioprinting techniques and choice of bioinks for both natural and synthetic polymers are also outlined. Lastly, current bioprinted tumor models are reviewed and the perspectives of how clinical applications can greatly benefit from 3D bioprinting technologies are offered.