Efficacy and Safety of Targeted Intramyocardial Delivery of Auto CD34+ Stem Cells for Improving Exercise Capacity in Subjects With Refractory Angina

Main Inclusion Criteria: * Male or female participants who are 21 to 80 years of age at the time of signing the informed consent. * Participants with Canadian Cardiovascular Society (CCS) class III or IV chronic refractory angina. * Participants without control of their angina symptoms in spite of maximal tolerated doses of anti-angina drugs. Participants must be on optimal therapy for their angina and must have been on a stable anti-anginal medication regimen for at least 4 weeks before signing the informed consent form. * Participants with obstructive coronary disease unsuitable for conventional revascularization due to unsuitable anatomy or comorbidity as determined at the site and confirmed by an independent adjudication committee. * Participants must have evidence of inducible myocardial ischemia. * Participants must experience angina episodes. * Participants must be able to complete 2 exercise tolerance tests on the treadmill within 3 weeks of randomization. * If female of childbearing potential, subject must not be pregnant and agree to employ adequate birth control measures for the duration of the study. Main Exclusion Criteria: * Cardiovascular hospitalization within 60 days prior to potential study enrollment. Participant has had a successful or partially successful coronary artery bypass graft (CABG) within 6 months or PCTA within 60 days of potential study enrollment. * Participant has had a placement of a bi-ventricular pacemaker for cardiac resynchronization therapy (CRT) for heart failure within 180 days of potential study enrollment. * Participant has documented stroke or transient ischemic attacks (TIAs) within 60 days of potential study enrollment. * Participant has a history of moderate to severe aortic stenosis; or severe aortic insufficiency; or severe mitral stenosis; or severe mitral insufficiency. * Participant has a prosthetic aortic valve or a mechanical mitral valve replacement. * Participant has severe co-morbidity associated with a reduction in life expectancy to less than 3 years as a result of chronic medical illnesses. * Participants with cancer are excluded with the following exceptions: * Subjects with in-situ non-melanoma skin cancer or in-situ cervical cancer are not excluded. * Participants that have been cancer free for \>= 5 years as determined by their oncologist are not excluded. Subjects with a prior history of stem cell transplant for cancer are excluded no matter how long they have been cancer-free. * Participant…