Inclusion Criteria: * Males and females, age 18 to 80 years * Diagnosis of chronic angina due to obstructive coronary artery disease that is refractory to drug therapy and unsuitable for revascularization via coronary artery bypass graft or percutaneous coronary intervention * Angina class II-IV based on Canadian Cardiovascular Society Classification of Angina Pectoris * Adequate hematologic (hemoglobin ≥ 10 g/dL, absolute neutrophil count \> 1.2 × 10\^3 per μL and platelet count ≥ 75,000 per μL), hepatic (alanine aminotransferase and aspartate aminotransferase ≤ 3 x ULN; total bilirubin ≤ 2 x ULN), and renal function (glomerular filtration rate \> 29 mL/minute/1.73 m2) * Adequate birth control if of child-bearing potential * Must be willing and able to provide informed consent Exclusion Criteria: * ST elevation myocardial infarction (STEMI) or non-ST elevation myocardial infarction (NSTEMI) not requiring revascularization, transmural myocardial infarction or cerebral vascular accident within the past 30 days * New York Heart Association Function Class III or IV or left ventricular ejection fraction \< 25% within the 6 weeks prior to the screening visit * HbA1c ≥ 8.5%, SBP \<90 or \>180 mmHg, DBP \>100 mmHg * Other concurrent medical conditions that could jeopardize the safety of the subject or objectives of the study