3D Printed Collagen Tracheal Scaffolds with Biomimetic Microstructure

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PROJECT SUMMARY/ABSTRACT Approximately 1 in 2000 children are born with a congenital airway malformation and others develop tracheal defects due to disease or trauma; an important subset of these patients needs a tracheal graft to regain airway patency. Many impactful discoveries and innovative strategies have resulted from over 75 years of research into development of a tracheal replacement, but there remains a need for a tracheal graft that is patient-specific and can provide long-term, intervention free treatment while growing with the patient. The research goal of this fellowship is to engineer a patient-specific, 3D bioprinted collagen tracheal graft that recapitulates the mechanical properties of native trachea by incorporating biomimetic microstructure. 3D bioprinting is a technology ideally suited for tackling this challenge, as it allows us to use native biological materials, like collagen type I and decellularized tracheal ECM, to construct grafts that exactly match patient anatomy. The Feinberg lab has developed a new generation of Freeform Reversible Embedding of Suspended Hydrogels (FRESH) bioprinting that will allow me to control the microstructure of printed scaffolds to reproduce the extracellular matrix organization found in native trachea. By matching regional tracheal mechanics to physiologic loading using 3D patterned biomimetic microstructure, this proposal will take an important step towards a durable, patient-specific, immunosuppression free treatment for long-segment tracheal defects. In the first aim I will use high resolution volumetric imaging to interrogate native tracheal extracellular matrix microstructure. These data sets will be used to design regionally appropriate biomimetic microstructures for different sections of the trachea (e.g. ring, connective tissue). These microstructural patterns are expected to recapitulate physiologic mechanical properties in both finite element analysis (FEA) models and 3D bioprinted collagen constructs. In the second aim I will use age-specific tracheal measurement data and deidentified medical imaging datasets to produce patient- specific pediatric tracheal graft geometries using open-source imaging segmentation tools. Regionally appropriate biomimetic microstructure will be patterned throughout these graft geometries. These biomimetic tracheal grafts will be modelled in FEA and then printed in collagen and mechanically characterized (e.g. collapsing forces, compliance, suturability) to demonstrate recapitulation of physiologically essential native tracheal mechanics. To accomplish this research, I have assembled a team with significant expertise in biomechanics, developmental biology, tissue engineering, and extracellular matrix. I have worked with this team to develop a rigorous training plan that will take advantage of the world class environment of Carnegie Mellon University and the University of Pittsburgh to help me build the technical and professional skillsets necessary for a productive physician-scientist. This proposal will jumpstart my long-term goals of investigating regenerative, functional tissue scaffolds for treatment of congenital, traumatic, and oncologic head and neck tissue defects while practicing as an otolaryngologist with a subspecialization in head and neck surgery.