Last time, a large number of publications on stem cells (SC) and cell therapies have emerged. Discussed topics include the differentiation of exogenous SC into various cell lineages, replacement of senescent, dysfunctional and damaged cells. Some studies claimed that transplanted SC regenerate infarcted rodent hearts. This work was translated to the clinic. However, efficacy in human studies has been nil or ambiguous. It has become clear that exogenous cells were not forming new cardiac tissue. The action mode of SC remains incompletely described; alternative mechanisms have been proposed: immunomodulating, paracrine and anti-aging. However, there are no reasons to assume that special functions would be more developed in SC than in differentiated cells. Allogeneic transplantations carry the risk of infections and immunologic adverse events. In conclusion, SC are a promising field of research. Studies of more differentiated cells and cell-free products mimicking paracrine effects of cell-based therapies are promising as well. Therapeutic methods with unproven effects should be tested within the framework of high quality research shielded from the funding bias.