Dynamic flow for efficient partial decellularization of tracheal grafts: A preliminary rabbit study.

Objective: Bioengineered tracheal grafts are a potential solution for the repair of long-segment tracheal defects. A recent advancement is partially decellularized tracheal grafts (PDTGs) which enable regeneration of host epithelium and retain viable donor chondrocytes for hypothesized benefits to mechanical properties. We propose a novel and tunable 3D-printed bioreactor for creating large animal PDTG that brings this technology closer to the bedside. Methods: Conventional agitated immersion with surfactant and enzymatic activity was used to partially decellularize New Zealand white rabbit (Oryctolagus cuniculus) tracheal segments (n = 3). In parallel, tracheal segments (n = 3) were decellularized in the bioreactor with continuous extraluminal flow of medium and alternating intraluminal flow of surfactant and medium. Unprocessed tracheal segments (n = 3) were also collected as a control. The grafts were assessed using the H&E stain, tissue DNA content, live/dead assay, Masson's trichrome stain, and mechanical testing. Results: Conventional processing required 10 h to achieve decellularization of the epithelium and submucosa with poor chondrocyte viability and mechanical strength. Using the bioreactor reduced processing time by 6 h and resulted in chondrocyte viability and mechanical strength similar to that of native trachea. Conclusion: Large animal PDTG created using our novel 3D printed bioreactor is a promising approach to efficiently produce tracheal grafts. The bioreactor offers flexibility and adjustability favorable to creating PDTG for clinical research and use. Future research includes optimizing flow conditions and transplantation to assess post-implant regeneration and mechanical properties. Level of Evidence: NA.

Oral and middle ear delivery of otitis media standard of care antibiotics, but not biofilm-targeted antibodies, alter chinchilla nasopharyngeal and fecal microbiomes.

Otitis media (OM) is one of the most globally pervasive pediatric conditions. Translocation of nasopharynx-resident opportunistic pathogens like nontypeable Haemophilus influenzae (NTHi) assimilates into polymicrobial middle ear biofilms, which promote OM pathogenesis and substantially diminish antibiotic efficacy. Oral or tympanostomy tube (TT)-delivered antibiotics remain the standard of care (SOC) despite consequences including secondary infection, dysbiosis, and antimicrobial resistance. Monoclonal antibodies (mAb) against two biofilm-associated structural proteins, NTHi-specific type IV pilus PilA (anti-rsPilA) and protective tip-region epitopes of NTHi integration host factor (anti-tip-chimer), were previously shown to disrupt biofilms and restore antibiotic sensitivity in vitro. However, the additional criterion for clinical relevance includes the absence of consequential microbiome alterations. Here, nine chinchilla cohorts (n = 3/cohort) without disease were established to evaluate whether TT delivery of mAbs disrupted nasopharyngeal or fecal microbiomes relative to SOC-OM antibiotics. Cohort treatments included a 7d regimen of oral amoxicillin-clavulanate (AC) or 2d regimen of TT-delivered mAb, AC, Trimethoprim-sulfamethoxazole (TS), ofloxacin, or saline. Fecal and nasopharyngeal lavage (NPL) samples were collected before and several days post treatment (DPT) for 16S sequencing. While antibiotic-treated cohorts displayed beta-diversity shifts (PERMANOVA, P < 0.05) and reductions in alpha diversity (q < 0.20) relative to baseline, mAb antibodies failed to affect diversity, indicating maintenance of a eubiotic state. Taxonomic and longitudinal analyses showed blooms in opportunistic pathogens (ANCOM) and greater magnitudes of compositional change (P < 0.05) following broad-spectrum antibiotic but not mAb treatments. Collectively, results showed broad-spectrum antibiotics induced significant fecal and nasopharyngeal microbiome disruption regardless of delivery route. Excitingly, biofilm-targeting antibodies had little effect on fecal and nasopharyngeal microbiomes.

Airway disease decreases the therapeutic potential of epithelial stem cells.

BACKGORUND: Tissue-engineered tracheal grafts (TETG) can be recellularized by the host or pre-seeded with host-derived cells. However, the impact of airway disease on the recellularization process is unknown. METHODS: In this study, we determined if airway disease alters the regenerative potential of the human tracheobronchial epithelium (hTBE) obtained by brushing the tracheal mucosa during clinically-indicated bronchoscopy from 48 pediatric and six adult patients. RESULTS: Our findings revealed that basal cell recovery and frequency did not vary by age or region. At passage 1, all samples produced enough cells to cellularize a 3.5 by 0.5 cm2 graft scaffold at low cell density (~ 7000 cells/cm2), and 43.75% could cellularize a scaffold at high cell density (~ 100,000 cells/cm2). At passage 2, all samples produced the number of cells required for both recellularization models. Further evaluation revealed that six pediatric samples (11%) and three (50%) adult samples contained basal cells with a squamous basal phenotype. These cells did not form a polarized epithelium or produce differentiated secretory or ciliated cells. In the pediatric population, the squamous basal cell phenotype was associated with degree of prematurity (< 28 weeks, 64% vs. 13%, p = 0.02), significant pulmonary history (83% vs. 34%, p = 0.02), specifically with bronchopulmonary dysplasia (67% vs. 19%, p = 0.01), and patients who underwent previous tracheostomy (67% vs. 23%, p = 0.03). CONCLUSIONS: In summary, screening high-risk pediatric or adult population based on clinical risk factors and laboratory findings could define appropriate candidates for airway reconstruction with tracheal scaffolds. LEVEL OF EVIDENCE: Level III Cohort study.

Assessing the Biocompatibility and Regeneration of Electrospun-Nanofiber Composite Tracheal Grafts.

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.

Long-Term Chondrocyte Retention in Partially Decellularized Tracheal Grafts.

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.

Surgical management of vocal cord nodules in children: Trends and outcomes.

OBJECTIVES: Vocal cord nodules (VCNs) are the most common cause of dysphonia in school-aged children, with potential negative impacts on quality of life including diminished self-esteem and academic performance. The standard of care for VCNs is conservative management which ranges from voice hygiene to speech therapy with a focus on voice otherwise known as voice therapy, with surgical excision reserved for refractory cases. Thus, few studies have analyzed outcomes of surgical management of VCNs. The purpose of this study is to assess the prevalence and efficacy of surgical excision of VCNs when compared to speech therapy. METHODS: Children with VCNs seen at a single tertiary care institution between 2015 and 2020 were identified by ICD-9 code 478.5 and ICD-10 code J38.2. Demographics, objective voice assessment, intervention, and follow-up assessment data were reviewed. Frequencies, medians, and interquartile ranges were calculated. Time to resolution and improvement were assessed by Cox proportional hazards model. Univariate logistic regression was performed. A P value of <0.05 was considered statistically significant. RESULTS: Three hundred sixty-eight patients diagnosed with VCNs were identified. 169 patients received intervention for VCNs, with 159 (43.2 %) receiving speech therapy alone and 5 (1.4 %) receiving surgery alone. On bivariate analysis, there was no significant difference in demographic features between treatment groups, however speech therapy patients did have a longer follow-up time. 154 patients underwent objective voice assessment at the time of VCN diagnosis. Among these patients, 95 (61.7 %) received speech therapy and 59 (40.3 %) received no intervention. Speech therapy patients had significantly higher pVHI scores, however there was no significant difference in CAPE-V Overall Severity scores or computerized voice assessment analysis. On Cox proportional hazards analysis, surgical intervention was associated with faster resolution and faster improvement of dysphonic symptoms. On binary logistic regression, surgery was associated with a significantly greater proportion of patients reporting resolution of dysphonic symptoms, however there was no significant difference in proportion of patients reporting improvement of dysphonia. CONCLUSION: For most patients with VCNs, conservative measures such as voice hygiene and speech therapy remain first line, however certain patients may benefit from the rapid improvement and resolution of symptoms that surgical intervention may provide.

Visual outcomes following orbital decompression for orbital infections.

OBJECTIVE: To analyze the visual outcomes and sequelae of endonasal intervention for orbital infections. INTRODUCTION: Orbital infections pose a serious threat to vision in the pediatric population and can result in complications such as blindness, diplopia, intracranial involvement, and death. [1] Orbital decompression by endonasal intervention is a common treatment to address a variety of orbital infections including orbital cellulitis, orbital abscesses, and subperiosteal abscesses. [2] The outcomes of visual sequelae such as loss or limitation of visual acuity, extraocular movements, and increased intraocular pressure following orbital decompression via endonasal intervention have not been sufficiently investigated in the current literature. METHODS: This retrospective cohort study was performed at our tertiary care pediatric hospital using data from 69 patients aged 0-18 years who were admitted between 2008 and 2018. Data was extracted from the electronic medical record system. RESULTS: Following endoscopic sinus surgery, symptoms of orbital infection improved throughout the cohort. Improvement in visual acuity is demonstrated by a statistically significant decrease in the average logMAR value in both the right and left eye (P = 0.002 and P = 0.028 respectively). There was also a significant improvement to normal values postoperatively for patients who initially presented with abnormal tonometry, extraocular movement, and the appearance of eyelids and eyelashes. CONCLUSION: There is no decline or loss of vision with otolaryngology surgical intervention for orbital cellulitis in our cohort. This retrospective chart review demonstrates the efficacy of surgical intervention on overall visual outcomes following endonasal intervention for orbital infections such as orbital cellulitis, orbital abscesses, and subperiosteal abscesses.

Partial decellularization eliminates immunogenicity in tracheal allografts.

There is currently no suitable autologous tissue to bridge large tracheal defects. As a result, no standard of care exists for long-segment tracheal reconstruction. Tissue engineering has the potential to create a scaffold from allografts or xenografts that can support neotissue regeneration identical to the native trachea. Recent advances in tissue engineering have led to the idea of partial decellularization that allows for the creation of tracheal scaffolds that supports tracheal epithelial formation while preserving mechanical properties. However, the ability of partial decellularization to eliminate graft immunogenicity remains unknown, and understanding the immunogenic properties of partially decellularized tracheal grafts (PDTG) is a critical step toward clinical translation. Here, we determined that tracheal allograft immunogenicity results in epithelial cell sloughing and replacement with dysplastic columnar epithelium and that partial decellularization creates grafts that are able to support an epithelium without histologic signs of rejection. Moreover, allograft implantation elicits CD8+ T-cell infiltration, a mediator of rejection, while PDTG did not. Hence, we establish that partial decellularization eliminates allograft immunogenicity while creating a scaffold for implantation that can support spatially appropriate airway regeneration.

Tracheostomy in Severe Bronchopulmonary Dysplasia-How to Decide in the Absence of Evidence.

Infants with the most severe forms of bronchopulmonary dysplasia (BPD) may require long-term invasive positive pressure ventilation for survival, therefore necessitating tracheostomy. Although life-saving, tracheostomy has also been associated with high mortality, postoperative complications, high readmission rates, neurodevelopmental impairment, and significant caregiver burden, making it a highly complex and challenging decision. However, for some infants tracheostomy may be necessary for survival and the only way to facilitate a timely and safe transition home. The specific indications for tracheostomy and the timing of the procedure in infants with severe BPD are currently unknown. Hence, centers and clinicians display broad variations in practice with regard to tracheostomy, which presents barriers to designing evidence-generating studies and establishing a consensus approach. As the incidence of severe BPD continues to rise, the question remains, how do we decide on tracheostomy to provide optimal outcomes for these patients?

Regeneration of tracheal neotissue in partially decellularized scaffolds.

Extensive tracheal injury or disease can be life-threatening but there is currently no standard of care. Regenerative medicine offers a potential solution to long-segment tracheal defects through the creation of scaffolds that support the generation of healthy neotissue. We developed decellularized tracheal grafts (PDTG) by removing the cells of the epithelium and lamina propria while preserving donor cartilage. We previously demonstrated that PDTG support regeneration of host-derived neotissue. Here, we use a combination of microsurgical, immunofluorescent, and transcriptomic approaches to compare PDTG neotissue with the native airway and surgical controls. We report that PDTG neotissue is composed of native tracheal cell types and that the neoepithelium and microvasculature persisted for at least 6 months. Vascular perfusion of PDTG was established within 2 weeks and the graft recruited multipotential airway stem cells that exhibit normal proliferation and differentiation. Hence, PDTG neotissue recapitulates the structure and function of the host trachea and has the potential to regenerate.

Optimization of Chondrocyte Viability in Partially Decellularized Tracheal Grafts.

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.

Assessing the Relationship Between Infection Frequency and Risk of Post-Tonsillectomy Hemorrhage.

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.

Successful Early Neovascularization in Composite Tracheal Grafts.

OBJECTIVE: Long-segment tracheal defects require tissue replacement for successful reconstruction. Rapid revascularization is imperative to maintain graft function. We previously showed that partially decellularized tracheal grafts (PDTG) and composite tracheal grafts (CTG; PDTG supported by a 3-dimensionally printed external splint) regenerate respiratory epithelium and may support the regeneration of endothelial cells (CD31+). However, the capability of graft endothelial cells to organize or contribute to tracheal revascularization remains unclear. In this study, we quantified endothelial cells (CD31+) and neovessel formation in PDTG and CTG. We hypothesize that PDTG and CTG support tracheal neovascularization to a similar extent as surgical (syngeneic tracheal graft [STG]) and native trachea (NT) controls. STUDY DESIGN: The animal study, a randomized control trial. SETTING: Center for Regenerative Medicine, Nationwide Children's Hospital. METHODS: PDTG was created via an established decellularization protocol. Segmental tracheal reconstruction was performed with STG, PDTG, or CTG using a mouse microsurgical model. NT was used as a nonsurgical control. At 1 month, mice were euthanized, grafts harvested, sectioned, and stained with CD31 and hematoxylin and eosin. Neovessel formation was quantified by the number of formed blood vessels in the lamina propria and vessel size (vessel/graft area, mm2 ). RESULTS: Decellularization eliminated all endothelial cells and there were no perfused vessels at implantation. At 1 month, PDTG and CTG supported neovessel formation with tubular vessels lined with endothelial cells. There was no difference in the number or size of vessels compared to controls. CONCLUSION: PDTG and CTG support tracheal endothelial cell regeneration and neovessel formation. Future directions to assess the function, kinetics, and distribution of graft neovessels are needed.

Association of Vibrotactile Biofeedback With Reduced Ergonomic Risk for Surgeons During Tonsillectomy.

Importance: Work-related musculoskeletal disorders are common among otolaryngologists and can be associated with decreased productivity, missed workdays, and reduced quality of life. Ergonomic risk for surgeons is elevated during common otolaryngology procedures; current ergonomic interventions lack the ability to provide real-time feedback. The ability to quantify and mitigate ergonomic risk during surgery may reduce work-related musculoskeletal disorders. Objective: To quantify the association of vibrotactile biofeedback with intraoperative ergonomic risk to surgeons during tonsillectomy. Design, Setting, and Participants: This cross-sectional study was conducted between June 2021 and October 2021 at a freestanding tertiary care children's hospital and included 11 attending pediatric otolaryngologists. Data analysis was conducted from August to October 2021. Interventions: Real-time quantification of ergonomic risk during tonsillectomy and the use of a vibrotactile biofeedback posture monitor. Main Outcomes and Measures: Association of vibrotactile biofeedback with objective measures of ergonomic risk. Assessment tools included the Rapid Upper Limb Assessment, craniovertebral angle, and time spent in an at-risk posture. Results: Eleven surgeons (mean [SD] age 42 [7] years; 2 women [18%]) performed 126 procedures with continuous posture monitoring in the presence (80 [63%]) and absence (46 [37%]) of vibrotactile biofeedback. No complications or delays associated with the device were reported. Intraoperative vibrotactile biofeedback was associated with improved Rapid Upper Limit Assessment neck, trunk, and leg scores by 0.15 (95% CI, 0.05-0.25), improved craniovertebral angle by 1.9 (95% CI, 0.32-3.40), and decreased overall time spent in an at-risk posture by 30% (95% CI, 22%-39%). Conclusions and Relevance: The results of this cross-sectional study suggest that use of a vibrotactile biofeedback device to quantify and mitigate ergonomic risk for surgeons is feasible and safe while performing surgery. Vibrotactile biofeedback was associated with reduced ergonomic risk during tonsillectomy and may have a role in improving surgical ergonomics and preventing work-related musculoskeletal disorders.

Dynamic Volumetric Computed Tomography Angiography is an Effective Method to Evaluate Tracheomalacia in Children.

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.

A Multimodal Approach to Quantify Chondrocyte Viability for Airway Tissue Engineering.

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.

Biobanked tracheal basal cells retain the capacity to differentiate.

Objective: While airway epithelial biorepositories have established roles in the study of bronchial progenitor stem (basal) cells, the utility of a bank of tracheal basal cells from pediatric patients, who have or are suspected of having an airway disease, has not been established. In vitro study of these cells can enhance options for tracheal restoration, graft design, and disease modeling. Development of a functional epithelium in these settings is a key measure. The aim of this study was the creation a tracheal basal cell biorepository and assessment of recovered cells. Methods: Pediatric patients undergoing bronchoscopy were identified and endotracheal brush (N = 29) biopsies were collected. Cells were cultured using the modified conditional reprogramming culture (mCRC) method. Samples producing colonies by day 14 were passaged and cryopreserved. To explore differentiation potential, cells were thawed and differentiated using the air-liquid interface (ALI) method. Results: No adverse events were associated with biopsy collection. Of 29 brush biopsies, 16 (55%) were successfully cultured to passage 1/cryopreserved. Samples with higher initial cell yields were more likely to achieve this benchmark. Ten unique donors were then thawed for analysis of differentiation. The average age was 2.2 ± 2.2 years with five donors (50%) having laryngotracheal pathology. Nine donors (90%) demonstrated differentiation capacity at 21 days of culture, as indicated by detection of ciliated cells (ACT+) and mucous cells (MUC5B+). Conclusion: Pediatric tracheal basal cells can be successfully collected and cryopreserved. Recovered cells retain the ability to differentiate into epithelial cell types in vitro. Level of Evidence: Level 3.

Effect of injection laryngoplasty material on outcomes in pediatric vocal fold paralysis.

Background: While injection laryngoplasty is becoming increasingly common in children, there has not been clearly established guidelines for the choice of injection material. This study evaluates for variability in post-surgical outcomes between different materials used for injection laryngoplasty in the treatment of pediatric unilateral vocal cord paralysis. Methods: In this cohort study, a retrospective chart review was performed for all patients undergoing injection laryngoplasty for unilateral vocal cord paralysis at our tertiary-care children's hospital between January 2010 and December 2019. Patients with vocal cord paresis or bilateral vocal cord paralysis were excluded from this study. Demographics, pre- and post-injection clinic visits, and operative reports were reviewed to compare outcomes between injection materials, including the number of injections required, inter-surgical interval, and rate of vocal improvement. Results: Forty-four patients were included in the analysis. Half of the patients were female, and half were male. A total of 97 injections were observed, with 32 patients receiving multiple injections. The mean age at first injection was 7 years. The most common causes of vocal fold paralysis were iatrogenic (n=21, 48%) and idiopathic (n=9, 20%). Thirty-nine percent (n=17) had a history of cardiac surgery. Forty-five percent of injections used Radiesse® voice/Prolaryn® plus, 35% used Radiesse®/Prolaryn® voice Gel, and 20% used Cymetra™. The material used was not associated with a difference in post-operative outcomes, including number of injections, (P=0.10; 0.29), inter-surgical interval (P=0.27; 0.29), or rate of voice improvement (P=0.86; 0.36). Conclusions: Neither material choice nor demographic factors were associated with a difference in outcomes following injection laryngoplasty or a change in the inter-surgical interval. Further research is needed to develop standardized protocols for injection laryngoplasty in this population.

Adverse Events in Infants Less Than 6 Months of Age After Ambulatory Surgery and Diagnostic Imaging Requiring Anesthesia.

AAP guidelines recommend infants less than 6 months of age are monitored for at least 2 hours following surgery. This retrospective study evaluated if adherence to the 2-hour monitoring guideline decreased the risk of adverse events associated with ambulatory procedures in infants younger than 6 months. Methods: We queried the hospital's electronic medical record to identify patients younger than 6 months of age who received anesthetic care from January 2015 to March 2020. Demographic data, intraoperative adverse events, and returns to the emergency department (ED) or urgent care within 7 days were captured for each patient. We calculated the number and frequency for categorical data and median and interquartile range (IQR) for continuous data. Chi-square or Fisher's exact test were used to compare patients who experienced an adverse event to those that did not. Results: One thousand one hundred seventy-seven patients who had 1,261 unique anesthetic encounters were analyzed. Forty-four adverse events were identified, 20 (1.6%) before discharge, including 3 unplanned admissions, and 24 (1.9%) returns to the ED/UC within 7 days postoperatively. We did not observe differences in postoperative recovery time in patients who experienced an adverse event and those who did not (88 min vs. 77 min, respectively, P = 0.078). None of the ED/UC returns would have been avoided by a longer PACU stay. Conclusions: With the appropriate patient selection, once physiological discharge readiness is met, adherence to a strict 2-hour time-based discharge criteria does not increase safety for infants younger than 6 months of age after ambulatory procedures.

Tissue-engineered composite tracheal grafts create mechanically stable and biocompatible airway replacements.

We tested composite tracheal grafts (CTG) composed of a partially decellularized tracheal graft (PDTG) combined with a 3-dimensional (3D)-printed airway splint for use in long-segment airway reconstruction. CTG is designed to recapitulate the 3D extracellular matrix of the trachea with stable mechanical properties imparted from the extraluminal airway splint. We performed segmental orthotopic tracheal replacement in a mouse microsurgical model. MicroCT was used to measure graft patency. Tracheal neotissue formation was quantified histologically. Airflow dynamic properties were analyzed using computational fluid dynamics. We found that CTG are easily implanted and did not result in vascular erosion, tracheal injury, or inflammation. Graft epithelialization and endothelialization were comparable with CTG to control. Tracheal collapse was absent with CTG. Composite tracheal scaffolds combine biocompatible synthetic support with PDTG, supporting the regeneration of host epithelium while maintaining graft structure.