In vivo tracking of stem cells for clinical trials in cardiovascular disease

Abstract—Various stem cells hold promise for the treatment of human cardiovascular disease. Regardless of stem cell origin, future clinical trials will require that the location and number of such cells be tracked in vivo, over long periods of time. The problem of tracking small numbers of cells in the body is a difficult one, and an optimal solution does not yet exist. We review the many contrast agents and detectors that have been proposed for stem cell tracking during clinical trials, define the characteristics of an ideal imaging technology, and suggest future directions for research. (Circulation. 2004;110:3378-3384.) Key Words: stem cells imaging trials radiology With the rapid increase of reported cases of stem cellsbeing used to treat cardiovascular disease, it has become apparent that an urgent need exists to track stem cells in vivo during clinical trials. For example, stem cell therapy for heart failure addresses an important problem in clinical medicine. Heart failure is a major cause of morbidity and mortality in the United States. The rates of new and recurrent heart failure events increase substantially with age. In patients aged 65 and older, conges-tive heart failure is the single most frequent cause of hospitalization in the United States. Despite substantial ad-vances in the clinical management of heart failure, the diagnosis continues to carry a grave prognosis with an overall 5-year mortality rate of 50%. This rate is substantially worse in more severely affected patient subsets. An under-standing of the role of stem cells in repopulating damaged areas in the heart would help target these diseased areas.1 The problem of imaging small numbers of cells in the living subject is not limited to stem cell–based treatments in cardiology but has broad applicability in oncology, immunol-ogy, and transplantation