Stem cell therapy has raised enthusiasm as a potential treatment for cardiovascular diseases. However, questions remain about the in vivo behavior of the cells after transplantation and the... Show moreStem cell therapy has raised enthusiasm as a potential treatment for cardiovascular diseases. However, questions remain about the in vivo behavior of the cells after transplantation and the mechanism of action with which the cells could potentially alleviate disease symptoms. The objective of the research as described in this thesis was to visualize survival, proliferation, and migration of embryonic (ESC) and adult stem cells using non-invasive molecular imaging techniques in small animal models of cardiovascular diseases. The major findings can be described as follows: (1) Non-invasive bioluminescence imaging is a validated tool to monitor donor cell survival, proliferation, migration, and misbehavior; (2) ESC are a potential source for true regenerative therapy; (3) ESC form teratomas; (4) Adult stem cell survival is short-lived, but of all cells currently used in the clinic, mononuclear cells show the most prolonged survival; (5) Transplantation of mononuclear cells can preserve cardiac function in the short term after myocardial infarction in mice; (6) Compared to other measurements of murine cardiac function, Micro-CT is a superior method to assess cardiac geometry and function; and (7) Transplantation of mononuclear cells in peripheral artery disease is hampered by dismal cell survival and homing. These findings illustrate the current challenges for optimizing stem cell therapy for cardiovascular disease. Show less