Stem cell therapy for chronic heart failure: an updated appraisal.

INTRODUCTION: Significant advances have been made to understand the mechanisms involved in cardiac cell-based therapies. The early translational application of basic science knowledge has led to several animal and human clinical trials. The initial promising beneficial effect of stem cells on cardiac function restoration has been eclipsed by the inability of animal studies to translate into sustained clinical improvements in human clinical trials. AREAS COVERED: In this review, the authors cover an updated overview of various stem cell populations used in chronic heart failure. A critical review of clinical trials conducted in advanced heart failure patients is proposed, and finally promising avenues for developments in the field of cardiac cell-based therapies are presented. EXPERT OPINION: Several questions remain unanswered, and this limits our ability to understand basic mechanisms involved in stem cell therapeutics. Human studies have revealed critical unresolved issues. Further elucidation of the proper timing, mode delivery and prosurvival factors is imperative, if the field is to advance. The limited benefits seen to date are simply not enough if the potential for substantial recovery of nonfunctioning myocardium is to be realized.