Project Grant F32HL186674

TISSUE MECHANICS AND EPITHELIAL REGENERATION IN CONGENITAL DIAPHRAGMATIC HERNIA-ASSOCIATED LUNG HYPOPLASIA - PROJECT SUMMARY/ABSTRACT CONGENITAL DIAPHRAGMATIC HERNIA (CDH) IS A RELATIVELY COMMON CONGENITAL DISORDER IN WHICH A DEFECT IN THE DIAPHRAGM PERMITS HERNIATION OF ABDOMINAL ORGANS INTO THE CHEST, THEREBY IMPAIRING LUNG MALDEVELOPMENT. CDH REMAINS A CONDITION WITH HIGH MORTALITY, LONG-TERM PULMONARY MORBIDITY, AND FEW TREATMENT OPTIONS. THE CAUSES OF CDH ARE LARGELY UNKNOWN BUT ARE ATTRIBUTED IN PART TO ALTERED MECHANICAL FORCES IN UTERO. THERE IS EVIDENCE OF SIGNIFICANTLY ALTERED WHOLE-LUNG MECHANICS IN CDH, AS WELL AS ALTERED YAP MECHANOSENSITIVE SIGNALING, WHICH MAY CONTRIBUTE TO THE IMPAIRED ALVEOLAR EPITHELIAL TYPE 2 CELL (AEC2) DIFFERENTIATION TO ALVEOLAR EPITHELIAL TYPE 1 CELLS (AEC1S), AS IS SEEN IN CDH. MORE BROADLY, THERE IS ACCUMULATING EVIDENCE THAT MECHANICAL FORCES ARE CRITICAL FOR PROPER LUNG DEVELOPMENT, HOMEOSTASIS, AND REPAIR AFTER INJURY, PARTICULARLY FOR THE ALVEOLAR EPITHELIUM. THIS PROJECT PROPOSES TO USE MATERIALS SCIENCE AND ENGINEERING STRATEGIES TO INVESTIGATE THE ROLE OF MICROMECHANICAL FORCES IN LUNG HYPOPLASIA IN CDH. SPECIFICALLY, THE OVERARCHING GOAL OF THIS PROPOSAL IS TO DEFINE THE IMPACT OF ALTERED TISSUE MECHANICAL PROPERTIES ON POSTNATAL LUNG MATURATION AND ALVEOLAR EPITHELIAL REGENERATION IN CDH-ASSOCIATED LUNG HYPOPLASIA. THE FIRST AIM SEEKS TO CHARACTERIZE THE EXTRACELLULAR MATRIX (ECM) AND INTRINSIC TISSUE MECHANICS (I.E. STIFFNESS AND VISCOELASTICITY) OF HYPOPLASTIC LUNGS USING THE NITROFEN MODEL OF CDH. THE SECOND AIM WILL USE THESE MECHANICAL MEASUREMENTS TO DEVELOP MECHANICALLY-TUNABLE ALGINATE-ECM HYDROGELS MIMICKING HEALTHY AND HYPOPLASTIC LUNG TISSUE. 3D ALVEOLOSPHERES OF PRIMARY AEC2S AND FIBROBLASTS WILL BE CULTURED WITHIN THE HYDROGEL MATRICES TO EXAMINE THE EFFECTS OF ALTERED MECHANICS ON ALVEOLAR EPITHELIAL PHENOTYPE, PROLIFERATION, AND DIFFERENTIATION. FINALLY, THE THIRD AIM WILL INVESTIGATE THE INTERACTION BETWEEN THE INTRINSIC MECHANICAL PROPERTIES OF HYPOPLASTIC LUNGS AND APPLIED CYCLIC LOADING MIMICKING VENTILATORY STRETCH - A KEY CUE FOR EPITHELIAL PROLIFERATION AND DIFFERENTIATION - USING COMPUTATIONAL MODELING AS WELL AS HYDROGEL ORGANOID CULTURES WITHIN A CYCLIC STRETCH BIOMIMETIC BIOREACTOR. THIS WORK MAY ULTIMATELY LEAD TO THE DEVELOPMENT OF THERAPIES TARGETING ALTERED TISSUE MECHANICS TO PROMOTE LUNG REGENERATION IN CDH AND OTHER CHRONIC LUNG DISEASES. FROM A TRAINING PERSPECTIVE, THIS PROJECT WILL AFFORD NEW EDUCATION IN BIOMECHANICS AND BIOMATERIALS; ACQUISITION OF SKILLS IN MECHANICAL CHARACTERIZATION, BIOMATERIALS SYNTHESIS, AND COMPUTATIONAL MODELING; AND ADDITIONAL TRAINING IN RESEARCH PROJECT DESIGN, COMMUNICATION, LEADERSHIP, AND MENTORSHIP - TOGETHER HELPING THE FELLOW TO MOVE TOWARD A CAREER AS AN INDEPENDENT SURGEON-SCIENTIST WORKING AT THE INTERSECTION OF PEDIATRIC SURGICAL DISEASE, DEVELOPMENT, AND REGENERATIVE MEDICINE. THE TRAINING ENVIRONMENT - COMPRISING A MULTIDISCIPLINARY LAB GROUP TOGETHER WITH THE EXTENSIVE RESOURCES AND EXPERTISE ACROSS HARVARD UNIVERSITY AND THE MASSACHUSETTS GENERAL HOSPITAL - WILL DIVERSIFY THE FELLOW'S SCIENTIFIC TRAINING AND STRENGTHEN THE FELLOW'S RESEARCH AND CLINICAL MENTORSHIP NETWORKS AS CRITICAL STEPS TOWARD INDEPENDENCE.