Abstract 3456: Autologous Implantation of Umbilical Cord Mononuclear Cells Preserves Right Ventricular Function in a Novel Model of Chronic Right Ventricular Volume Overload
Right ventricular dysfunction is a long-term complication after correction of Tetralogy of Fallot (TOF). We evaluated the effects of autologous umbilical cord mononuclear cell (UCMC) implantation on right ventricular function in a novel chronic right ventricular volume overload model. Four-month-old sheeps (n=20) were randomized into stem cell (n=10) and control groups (n=10). After measuring baseline right ventricular function by conductance catheters, a transannular patch was sutured to the RVOT. The ring of the pulmonary valve was transsected through the patch without cardiopulmonary bypass. Intramyocardial UCMC implantation in the stem cell group and medium injection in the control group were performed below the patch into the right ventricle. Echocardiographic analysis was employed after six weeks and right ventricular function was assessed using conductance catheters after three months. All animals were sacrificed for macroscopic, histological and immunohistochemical examinations. All animals survived the procedure. Echocardiographic measures revealed grade II-III pulmonary regurgitation in both groups. Pressure-volume loops under dobutamine-stress showed significantly better diastolic performance of the right ventricle in the stem cell group (EDPVR: p=0.017, dp/dtmin: p=0.043). CD31 staining indicated significantly enhanced number of microvessels in the region of UCMC implantation in the stem cell group. No adverse tissue changes were observed in the computed tomography or histological examinations. Transan-nular patch augmentation and pulmonary annulus distortion without cardiopulmonary bypass constitutes a valid large animal model mimicking postoperative TOF patients. Our results indicate right ventricular function profits from autologous UCMC implantation by enhanced diastolic properties with a probable mechanism of increased angiogenesis following chronic volume overload.