 On the day of surgery, once all of the bypass grafts have been placed, a high or low dose of MSCs or placebo will be injected into a damaged area of the heart that did not receive a bypass graft. After receiving the injections, participants will remain in the hospital for up to 7 days. During this stay, participants will undergo a daily blood draw, urine test, ECG, and ambulatory ECG monitoring for the first 96 hours after surgery. 