Transplantation of Human Embryonic Stem Cell-Derived Cardiovascular Progenitors for Severe Ischemic Left Ventricular Dysfunction

BACKGROUND In addition to scalability, human embryonic stem cells (hESCs) have the unique advantage of allowing their directed differentiation toward lineage-specific cells. OBJECTIVES This study tested the feasibility of leveraging the properties of hESCs to generate clinical-grade cardiovascular progenitor cells and assessed their safety in patients with severe ischemic left ventricular dysfunction. METHODS Six patients (median age 66.5 years [interquartile range (IQR): 60.5 to 74.7 years]; median left ventricular ejection fraction 26% [IQR: 22% to 32%]) received a median dose of 8.2 million (IQR: 5 to 10 million) hESC-derived cardiovascular progenitors embedded in a fibrin patch that was epicardially delivered during a coronary artery bypass procedure. The primary endpoint was safety at 1 year and focused on: 1) cardiac or off-target tumor, assessed by imaging (computed tomography and fluorine-18 fluorodeoxyglucose positron emission tomography scans); 2) arrhythmias, detected by serial interrogations of the cardioverter-defibrillators implanted in all patients; and 3) alloimmunization, assessed by the presence of donor-specific antibodies. Patients were followed up for a median of 18 months. RESULTS The protocol generated a highly purified (median 97.5% [IQR: 95.5% to 98.7%]) population of cardiovascular progenitors. One patient died early post-operatively from treatment-unrelated comorbidities. All others had uneventful recoveries. No tumor was detected during follow-up, and none of the patients presented with arrhythmias. Three patients developed clinically silent alloimmunization. All patients were symptomatically improved with an increased systolic motion of the cell-treated segments. One patient died of heart failure after 22 months. CONCLUSIONS This trial demonstrates the technical feasibility of producing clinical-grade hESC-derived cardiovascular progenitors and supports their short-and medium-term safety, thereby setting the grounds for adequately powered efficacy studies. (Transplantation of Human Embryonic Stem Cell-derived Progenitors in Severe Heart Failure [ESCORT]; NCT02057900) (c) 2018 by the American College of Cardiology Foundation.