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Objective: Composite tracheal grafts (CTG) combining decellularized scaffolds with external biomaterial support have been shown to support host‐derived neotissue formation. In this study, we examine the biocompatibility, graft epithelialization, vascularization, and patency of three prototype CTG using a mouse microsurgical model. Study Design: Tracheal replacement, regenerative medicine, biocompatible airway splints, animal model. Method: CTG electrospun splints made by combining partially decellularized tracheal grafts (PDTG) with polyglycolic acid (PGA), poly(lactide‐co‐ε‐caprolactone) (PLCL), or PLCL/PGA were orthotopically implanted in mice (N = 10/group). Tracheas were explanted two weeks post‐implantation. Micro‐Computed Tomography was conducted to assess for graft patency, and histological analysis was used to assess for epithelialization and neovascularization. Result: Most animals (greater than 80%) survived until the planned endpoint and did not exhibit respiratory symptoms. MicroCT confirmed the preservation of graft patency. Grossly, the PDTG component of CTG remained intact. Examining the electrospun component of CTG, PGA degraded significantly, while PLCL+PDTG and PLCL/PGA + PDTG maintained their structure. Microvasculature was observed across the surface of CTG and infiltrating the pores. There were no signs of excessive cellular infiltration or encapsulation. Graft microvasculature and epithelium appear similar in all groups, suggesting that CTG did not hinder endothelialization and epithelialization. Conclusion: We found that all electrospun nanofiber CTGs are biocompatible and did not affect graft patency, endothelialization and epithelialization. Future directions will explore methods to accelerate graft regeneration of CTG. Level of Evidence: N/A Laryngoscope, 134:1155–1162, 2024 [ABSTRACT FROM AUTHOR]

Objective: Decellularized tracheal grafts possess the biological cues necessary for tissue regeneration. However, conventional decellularization approaches to target the removal of all cell populations including chondrocytes lead to a loss of mechanical support. We have created a partially decellularized tracheal graft (PDTG) that preserves donor chondrocytes and the mechanical properties of the trachea. In this study, we measured PDTG chondrocyte retention with a murine microsurgical model. Study Design: Murine in vivo time‐point study. Setting: Research Institute affiliated with Tertiary Pediatric Hospital. Methods: PDTG was created using a sodium dodecyl sulfate protocol. Partially decellularized and syngeneic grafts were orthotopically implanted into female C57BL/6J mice. Grafts were recovered at 1, 3, and 6 months postimplant. Pre‐ and postimplant grafts were processed and analyzed via quantitative immunofluorescence. Chondrocytes (SOX9+, DAPI+) present in the host and graft cartilage was evaluated using ImageJ. Results: Partial decellularization resulted in the maintenance of gross tracheal architecture with the removal of epithelial and submucosal structures on histology. All grafts demonstrated SOX9+ chondrocytes throughout the study time points. Chondrocytes in PDTG were lower at 6 months compared to preimplant and syngeneic controls. Conclusion: PDTG retained donor graft chondrocytes at all time points. However, PDTG exhibits a reduction in chondrocytes at 6 months. The impact of these histologic changes on cartilage extracellular matrix regeneration and repair remains unclear. [ABSTRACT FROM AUTHOR]

Objective: Advancements in tissue‐engineered tracheal replacement (TETR) show promise for the use of partially decellularized tracheal grafts (PDTG) to address critical gaps in airway management and reconstruction. In this study, aiming to leverage the immunoprivileged nature of cartilage to preserve tracheal biomechanics, we optimize PDTG for retention of native chondrocytes. Study Design: Comparison in vivo murine study. Setting: Research Institute affiliated with Tertiary Pediatric Hospital. Methods: PDTG were created per a shortened decellularization protocol using sodium dodecyl sulfate, then biobanked via cryopreservation technique. Decellularization efficiency was characterized by DNA assay and histology. Viability and apoptosis of chondrocytes in preimplanted PDTG and biobanked native trachea (control) was assessed with live/dead and apoptosis assays. PDTG (N = 5) and native trachea (N = 6) were orthotopically implanted in syngeneic recipients for 1‐month. At the endpoint, microcomputed tomography (micro‐CT) was employed to interrogate graft patency and radiodensity in vivo. Vascularization and epithelialization were qualitatively analyzed using histology images following explant. Results: PDTG exhibited complete decellularization of all extra‐cartilaginous cells and reduced DNA content compared to control. Chondrocyte viability and nonapoptotic cell populations were improved utilizing biobanking and shorter decellularization time. All grafts remained patent. Evaluation of graft radiodensity at 1 month revealed elevation of Hounsfield units in both PDTG and native compared to host, with PDTG showing higher radiodensity than native. PDTG supported complete epithelialization and functional reendothelialization 1‐month postimplantation. Conclusion: Optimizing PDTG chondrocyte viability is a key component to successful tracheal replacement. Ongoing research seeks to evaluate the acute and chronic immunogenicity of PDTG. [ABSTRACT FROM AUTHOR]

Objective: To determine the relationship between frequency of tonsillitis and the risk of post-tonsillectomy hemorrhage (PTH) in pediatric patients undergoing tonsillectomy for recurrent tonsillitis. Methods: After obtaining IRB approval from Nationwide Children's Hospital, charts for all patients who underwent a total tonsillectomy in 2017 for recurrent or chronic tonsillitis were retrospectively reviewed (n = 424). Patients were divided into 2 cohorts based on the frequency of tonsillitis prior to surgery: those meeting the 1-year criteria with 7 or more infections in the past year (n = 100), and those who did not meet criteria defined as those with fewer than 7 infections in the past year (n = 324). The primary outcome of interest was PTH. Comparison of cohorts and frequency of PTH were assessed using bivariate analyses. Kaplan-Meier curves were used to compare time to onset of hemorrhage between primary vs. secondary PTH. Generalized mixed and logistic regression models were used to evaluate risk of hemorrhage following tonsillectomy. Results: Among a total cohort of 424 patients undergoing tonsillectomy, 23.58% (n = 100) met criteria while 76.42% (n = 324) did not. A total of 8.73% (n = 37) patients experienced PTH. Compared to those who did not meet criteria, those who met criteria had a higher odds of developing PTH; however, this was not significant (OR: 1.42 [95% CI: 0.67, 2.98], P =.3582). Estimated probability of developing PTH for those who met criteria was 11% [95% CI: 6.19, 18.81] compared to 8.03% [95% CI: 5.52, 11.54] for those who did not meet criteria. Among all PTH cases, 5.41% (n = 2) were primary hemorrhage while 94.59% (n = 35) were secondary hemorrhage with 50% of those with secondary PTH having experienced hemorrhage within 6 days [95% CI: 5, 7] of tonsillectomy. Patients with neuromuscular conditions had significantly higher odds of PTH (OR: 4.75 [95% CI: 1.19, 18.97], P =.0276). Conclusion: Patients who met the 1-year criteria for tonsillectomy did not have a significantly higher odds of PTH. Further research is needed to better evaluate the relationship between infection frequency and risk of PTH. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis: Partially decellularized tracheal scaffolds have emerged as a potential solution for long‐segment tracheal defects. These grafts have exhibited regenerative capacity and the preservation of native mechanical properties resulting from the elimination of all highly immunogenic cell types while sparing weakly immunogenic cartilage. With partial decellularization, new considerations must be made about the viability of preserved chondrocytes. In this study, we propose a multimodal approach for quantifying chondrocyte viability for airway tissue engineering. Methods: Tracheal segments (5 mm) were harvested from C57BL/6 mice, and immediately stored in phosphate‐buffered saline at −20°C (PBS‐20) or biobanked via cryopreservation. Stored and control (fresh) tracheal grafts were implanted as syngeneic tracheal grafts (STG) for 3 months. STG was scanned with micro‐computed tomography (μCT) in vivo. STG subjected to different conditions (fresh, PBS‐20, or biobanked) were characterized with live/dead assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and von Kossa staining. Results: Live/dead assay detected higher chondrocyte viability in biobanked conditions compared to PBS‐20. TUNEL staining indicated that storage conditions did not alter the proportion of apoptotic cells. Biobanking exhibited a lower calcification area than PBS‐20 in 3‐month post‐implanted grafts. Higher radiographic density (Hounsfield units) measured by μCT correlated with more calcification within the tracheal cartilage. Conclusions: We propose a strategy to assess chondrocyte viability that integrates with vivo imaging and histologic techniques, leveraging their respective strengths and weaknesses. These techniques will support the rational design of partially decellularized tracheal scaffolds. Level of Evidence: N/A Laryngoscope, 133:512–520, 2023 [ABSTRACT FROM AUTHOR]

Objective: Standard methods to evaluate tracheal pathology in children, including bronchoscopy, may require general anesthesia. Conventional dynamic proximal airway imaging in noncooperative children requires endotracheal intubation and/or medically induced apnea, which may affect airway mechanics and diagnostic performance. We describe a technique for unsedated dynamic volumetric computed tomography angiography (DV‐CTA) of the proximal airway and surrounding vasculature in children and evaluate its performance compared to the reference‐standard of rigid bronchoscopy. Methods: Children who had undergone DV‐CTA and bronchoscopy in one‐year were retrospectively identified. Imaging studies were reviewed by an expert reader blinded to the bronchoscopy findings of primary or secondary tracheomalacia. Airway narrowing, if present, was characterized as static and/or dynamic, with tracheomalacia defined as >50% collapse of the tracheal cross‐sectional area in exhalation. Pearson correlation was used for comparison. Results: Over a 19‐month period, we identified 32 children (median age 8 months, range 3–14 months) who had undergone DV‐CTA and bronchoscopy within a 90‐day period of each other. All studies were unsedated and free‐breathing. The primary reasons for evaluation included noisy breathing, stridor, and screening for tracheomalacia. There was excellent agreement between DV‐CTA and bronchoscopy for diagnosis of tracheomalacia (κ = 0.81, p < 0.001), which improved if children (n = 25) had the studies within 30 days of each other (κ = 0.91, p < 0.001). CTA provided incremental information on severity, and cause of secondary tracheomalacia. Conclusion: For most children, DV‐CTA requires no sedation or respiratory manipulation and correlates strongly with bronchoscopy for the diagnosis of tracheomalacia. Level of Evidence: 3 Laryngoscope, 133:410–416, 2023 [ABSTRACT FROM AUTHOR]