Laryngotracheal Reconstruction with Engineered Cartilage

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PROJECT SUMMARY/ABSTRACT Severe subglottic stenosis, the narrowing of the airway just below the vocal folds, develops as a response to intubation in close to 10% of the > 20,000 premature births per year in the United States. Severe cases require laryngotracheal reconstruction (LTR), in which surgeons split the cricoid and add a piece of autologous patient- derived cartilage to expand the airway and restore proper airflow. However, in children, the success rate is as low as 50% with a high incidence of restenosis requiring revision surgery. Graft failure is tied directly to the lack of sufficiently sized autologous cartilage in the child, and tissue engineering has been proposed to develop alterative grafting options for pediatric LTR. Some approaches, including some of our previous work, have been effective in producing functional cartilage, but the overall timeframe required for the construct to match the mechanical properties of native cartilage (>24 weeks) is not compatible with clinical translation (<8 weeks). Furthermore, current cell sources such as expanded autologous chondrocytes and mesenchymal stem cells frequently result in hypertrophic and calcified tissue. Our objective is to engineer a new type of cartilage implant that is populated with patients’ cells, mechanically viable and suitable for LTR within a clinically relevant timeframe. Our approach uses a microstructured polymeric scaffold with over 90% porosity and sufficient mechanical properties and with a pore structure uniquely capable of enhancing chondrogenesis of stem cells. Furthermore, cartilage progenitor cells have been proposed as a rapidly proliferating, highly chondrogenic cell source. To harness these cells, we have developed a minimally invasive biopsy procedure to harvest ear Cartilage Progenitor Cells (eCPCs). Our overarching hypothesis is that the microstructured polymeric scaffold combined with eCPCs will create cartilage implants with suitable mechanical strength, dimensions, and phenotypic stability for personalized, minimally invasive LTR. We propose to identify the microstructure that achieves the maximum chondrogenesis and the specific mechanism of action. The capacity of eCPCs to produce a robust cartilage phenotype, potentially better than that of ear chondrocytes and less prone to calcification, will also be studied. Finally, the engineered cartilage derived from the eCPCs seeded in the microporous scaffold will be test in a porcine LTR model. We expect that our findings will introduce a major innovation in the treatment of subglottic stenosis, laying the basis for long term pre-clinical safety studies and clinical translation in airway reconstructive surgery in children.