This two-part study will determine whether stem cells (primitive cells produced by the bone marrow that can develop into blood cells or other types of cells) can be pushed out into the bloodstream, relocate in the heart, and grow new heart muscle and blood vessels in patients with chest pain caused by narrowing of their coronary (heart) arteries. The new blood vessels may enable patients to do more activities before experiencing chest pain. Part 1 of the study will evaluate in a small number of patients whether an increase in white blood cells following administration of G-CSF (a drug used to move stem cells from the bone marrow to the bloodstream) is safe in people with coronary heart disease. Part 2 will evaluate the effects of the circulating stem cells on heart function.