Project Grant F30HL188773

A BIOENGINEERED, PERFUSABLE CARDIAC SPHEROID SYSTEM TO MODEL ENDOTHELIAL DYSFUNCTION IN HEART FAILURE - PROJECT SUMMARY/ABSTRACT: HEART FAILURE WITH PRESERVED EJECTION FRACTION (HFPEF) IS A CHRONIC CARDIOVASCULAR DISEASE CHARACTERIZED BY AN IMPAIRED CAPACITY OF THE HEART TO RELAX DURING DIASTOLE. HFPEF ACCOUNTS FOR OVER HALF OF ALL HEART FAILURE DIAGNOSES, AND IS MARKED BY EXERTIONAL DYSPNEA, FATIGUE, AND INCREASED ALL-CAUSE MORTALITY. PATIENTS LIVING WITH HFPEF HAVE A REDUCED QUALITY OF LIFE AND IMPOSE A SUBSTANTIAL ECONOMIC HEALTHCARE BURDEN. DESPITE RECENT IMPROVEMENTS IN PHARMACOLOGIC THERAPIES FOR OTHER CLASSES OF HEART FAILURE, VERY FEW DRUGS HAVE DEMONSTRATED SIGNIFICANT IMPROVEMENTS IN HFPEF MORTALITY. WHILE THE PRIMARY CLINICAL SYMPTOMS OF HFPEF RESULT FROM CARDIOMYOCYTE HYPERTROPHY AND FIBROSIS, ENDOTHELIAL CELL DYSFUNCTION (ECD) WITHIN THE CARDIAC MICROVASCULATURE IS A HALLMARK FEATURE OF HFPEF AND MAY PLAY A CRITICAL ROLE IN INITIATING AND PROPAGATING THESE CARDIAC MANIFESTATIONS. THIS PROPOSAL LEVERAGES A NOVEL HUMAN-BASED, VASCULARIZED, AND PERFUSABLE CARDIAC SPHEROID AND MICROVASCULAR NETWORK (CS-MVN) SYSTEM TO SYSTEMATICALLY INVESTIGATE THE INTERACTIONS BETWEEN THE CARDIAC ENDOTHELIUM AND CARDIOMYOCYTES. THE TRANSCRIPTION FACTOR KRYPPEL-LIKE FACTOR 2 (KLF2) HAS EMERGED AS A POWERFUL MEDIATOR OF ENDOTHELIAL HOMEOSTASIS, AND ITS EXPRESSION IS CURTAILED IN ECD. SUPPRESSION OF KLF2 IN THE CARDIAC MICROVASCULATURE HAS BEEN OBSERVED IN HUMAN PATIENTS WITH HEART FAILURE, IN A RAT MODEL OF HFPEF, AND IN THE CS-MVN SYSTEM FOLLOWING EXPOSURE TO PERFUSED FACTORS THAT MIMIC THE CIRCULATORY MILIEU OF HFPEF. THE WORKING HYPOTHESIS OF THE PROPOSED STUDIES IS THAT ECD IN THE CARDIAC MICROVASCULATURE IS MEDIATED BY KLF2 SUPPRESSION, WHICH DISRUPTS ENDOTHELIAL-CARDIOMYOCYTE SIGNALING IN HFPEF AND ACTS AS A CRITICAL DRIVER OF HFPEF-ASSOCIATED CARDIAC CHANGES. TO TEST THIS HYPOTHESIS, AIM 1 WILL DEFINE THE ROLE OF KLF2 AND ITS DOWNSTREAM TRANSCRIPTIONAL TARGETS WITHIN THE CARDIAC SPHEROID-ASSOCIATED VASCULATURE THROUGH ENDOTHELIAL- SPECIFIC KNOCKDOWN OF KLF2, FOLLOWED BY ASSESSMENT OF ECD AND CARDIOMYOCYTE FUNCTION. AIM 2 WILL CHARACTERIZE THE ENDOTHELIAL RESPONSE TO PERFUSED FACTORS THAT MIMIC THE CIRCULATORY MILIEU OF HFPEF PATIENTS AND EVALUATE THE IMPACT OF ECD ON PATHOLOGIC CARDIOMYOCYTE STATES. FINALLY, IN AIM 3, TARGETED KLF2 INDUCTION IN THE CS-MVN VASCULATURE WILL BE ASSESSED FOR ITS ABILITY TO REVERSE HFPEF-ASSOCIATED STRUCTURAL AND FUNCTIONAL CHANGES. THE PROPOSED PROJECT AIMS TO PROVIDE INSIGHT INTO THE MECHANISMS BY WHICH THE MICROVASCULAR ENDOTHELIUM GOVERNS THE PHYSIOLOGIC OR PATHOLOGIC STATE OF THE TISSUE IT SUPPLIES, WHILE POTENTIALLY REVEALING NEW THERAPEUTIC TARGETS FOR HFPEF AND OTHER DISEASES INVOLVING ECD. THE ACCOMPANYING FELLOWSHIP TRAINING PLAN INCORPORATES TAILORED TECHNICAL TRAINING, OPPORTUNITIES FOR SCIENTIFIC COMMUNICATION AND MENTORSHIP, AND LONGITUDINAL CLINICAL EXPERIENCES IN THE VIBRANT RESEARCH ENVIRONMENT OF HARVARD MEDICAL SCHOOL, BRIGHAM AND WOMEN'S HOSPITAL, AND MASSACHUSETTS INSTITUTE OF TECHNOLOGY. THESE OPPORTUNITIES HAVE BEEN CAREFULLY SELECTED TO SUPPORT THE FELLOWSHIP TRAINEE'S OVERALL CAREER GOALS AS A PHYSICIAN-SCIENTIST CONDUCTING INDEPENDENT RESEARCH AT THE INTERSECTION OF VASCULAR BIOLOGY, BIOMEDICAL ENGINEERING, AND CHRONIC DISEASE MODELING.