Cell therapies hold the potential for suppression, modification, or cure of disease. Several unique challenges have been recognized as this field has developed. Many of these involve considerations of trial design. This paper summarizes the discussion and suggestions constructed during the 8th Cardiovascular Clinical Trialists Workshop, a meeting involving cardiovascular clinical trialists, biostatisticians, National Institutes of Health scientists, European and United States regulators, and pharmaceutical industry scientists. Investigators must adapt research methods to accommodate the scientific advances associated with cell therapy. Safety and efficacy of cell therapy for cardiovascular indications should be evaluated with the same degree of scientific rigor required of pharmacologic agents, and the same fundamental regulatory requirements and scientific processes apply to both. Clinical trials for these indications should also meet standards similar to those set for drug therapies. Safety should be determined throughout development, dose responsiveness should be established and, while surrogate endpoints are important development tools, the ultimate demonstration of efficacy must rely on clinical benefit. The establishment of a global safety database for cell therapy would significantly advance the field. Efforts to discover innovative therapies must be balanced by a commitment to comprehensively evaluate the safety and efficacy of the new treatments.