Vocal Fold Injury Produces Similar Biomechanical Outcomes in Male and Female Rabbits.

OBJECTIVE: Sex differences in response to trauma and physiologic stressors have been identified in numerous organ systems but have not yet been defined in the larynx. The objective of this study was to develop an endoscopic vocal fold injury model in rabbits and to compare structural and functional outcomes between male and female subjects. STUDY DESIGN: Basic science study. METHODS: Two male and two female rabbits underwent unilateral endoscopic cordectomy. Animals were intubated with a size 3-0 neonatal endotracheal tube, and laryngoscopy was performed with a 4 mm Hopkins rod telescope. While visualizing, a 2 mm cupped forceps grasped and resected the mid-membranous portion of the right true vocal fold. Larynges were then harvested after 8weeks. Excised larynx phonation with high-speed videography and kymography was used to assess vibrational quality. Tissue elastic (Young's) modulus was measured by indentation. RESULTS: Injured larynges phonated with fundamental frequencies between 237-415 Hz. In both males and females, the scarred vocal fold exhibited an increased Young's modulus compared to the contralateral nonoperated vocal fold. There were no notable differences in glottal closure pattern or vocal fold oscillation symmetry between sexes. CONCLUSION: We have demonstrated a model for vocal fold scarring in rabbits. Vibrational and structural outcomes were similar between the examined male and female larynges.

Cell-Based Outer Vocal Fold Replacement Both Treats and Prevents Vocal Fold Scarring in Rabbits.

OBJECTIVE: Numerous pharmacological and cell-based treatments have shown promise in preventing vocal fold (VF) scarring when applied at the time of injury. A common clinical scenario, however, is the finding of mature scar impeding voicing. Many treatments are less effective in remodeling existing scar tissue. This objective of this study is to determine if a cell-based outer vocal fold replacement (COVR) effectively restores VF function when applied to existing scar. METHODS: Eighteen rabbits were allocated to three groups: unilateral COVR implant at the time of cordectomy (acute COVR); unilateral cordectomy followed by COVR implant 2 months later (chronic COVR); and unilateral cordectomy followed by sham implant surgery 2 months later (chronic scar). Larynges were harvested 2 months after implant or sham surgery. RESULTS: All larynges in the COVR groups demonstrated human leukocyte antigen labeling on immunohistochemistry (IHC). COVR groups had increased hyaluronic acid content compared with normal. VF stiffness as measured by elastic moduli in acute COVR and chronic COVR were similar to their contralateral unoperated VF. CONCLUSION: COVR implantation in both acutely injured and chronically scarred VF demonstrate persistence of implanted cells, restored tissue biomechanics, and increased hyaluronic acid content. LEVEL OF EVIDENCE: NA Laryngoscope, 134:764-772, 2024.

New Therapies in Head and Neck Cancer.

Head and neck squamous cell carcinoma (HNSCC) is a common malignancy with high rates of mortality and morbidity. Beginning with cetuximab, investigators continue to optimize antibody technology to target cell-surface receptors that promote HNSCC growth. Small molecules and oligonucleotides have also emerged as therapeutic inhibitors of key receptor-mediated signaling pathways. Although many such therapies have been disappointing in clinical trials as single agents, they continue to be studied in combination with standard therapies. Approvals of pembrolizumab and nivolumab opened a new era of immunotherapy that aims to stimulate antitumor immunity in the tumor microenvironment. Immunotherapies are being intensively investigated in new HNSCC clinical trials, with the goal of optimizing the therapeutic potential of this new class of anticancer agent.

Red colored IgG4 caused by vitamin B12 from cell culture media combined with disulfide reduction at harvest.

While many antibody therapeutics are formulated at low concentration (~10-20 mg/mL) for intravenous administration, high concentration (> 100 mg/mL) formulations may be required for subcutaneous delivery in certain clinical indications. For such high concentration formulations, product color is more apparent due to the higher molecular density across a given path-length. Color is therefore a product quality attribute that must be well-understood and controlled, to demonstrate process consistency and enable clinical trial blinding. Upon concentration of an IgG4 product at the 2000 L manufacturing scale, variability in product color, ranging from yellow to red, was observed. A small-scale experimental model was developed to assess the effect of processing conditions (medium composition and harvest conditions) on final bulk drug substance (BDS) color. The model was used to demonstrate that, for two distinct IgG4 products, red coloration occurred only in the presence of disulfide reduction-mediated antibody dissociation. The red color-causing component was identified as vitamin B 12, in the hydroxocobalamin form, and the extent of red color was correlated with the cobalt (vitamin B 12) concentration in the final pools. The intensity of redness in the final BDS was modulated by changing the concentration of vitamin B 12 in the cell culture media.

Comparative metabolite analysis to understand lactate metabolism shift in Chinese hamster ovary cell culture process.

A metabolic shift from lactate production (LP) to net lactate consumption (LC) phenotype was observed in certain Chinese hamster ovary (CHO) cell lines during the implementation of a new chemically defined medium (CDM) formulation for antibody production. In addition, this metabolic shift typically leads to process performance improvements in cell growth, productivity, process robustness, and scalability. In our previous studies, a correlation between a key media component, copper, and this lactate metabolism shift was observed. To further investigate this phenomenon, two complementary studies were conducted. In the first study, a single cell line was cultivated in two media that only differed in their copper concentrations, yet were known to generate an LP or LC phenotype with that cell line. In the second study, two different cell lines, which were known to possess inherently different lactate metabolic characteristics, were cultivated in the same medium with a high level of copper; one cell line produced lactate throughout the duration of the culture, and the other consumed lactate after an initial period of LP. Cell pellet and supernatant samples from both studies were collected at regular time intervals, and their metabolite profiles were investigated. The primary finding from the metabolic analysis was that the cells in LP conditions exhibited a less efficient energy metabolism, with glucose primarily being converted into pyruvate, sorbitol, lactate, and other glycolytic intermediates. This decrease in energy efficiency may be due to an inability of pyruvate and acetyl-CoA to progress into the TCA cycle. The lack of progression into the TCA cycle or overflow metabolism in the LP phenotype resulted in the inadequate supply of ATP for the cells. As a consequence, the glycolysis pathway remained the major source of ATP, which in turn, resulted in continuous LP throughout the culture. In addition, the accumulation of free fatty acids was observed; this was thought to be a result of phospholipid catabolism that was being used to supplement the energy produced through glycolysis in order to meet the needs of LP cells. A thorough review of the metabolic profiles indicated that the lactate metabolic shift could be related to the oxidative metabolic capacity of cells.