ABSTRACT

This short report is an overview of recent literature on stem cells and cell therapies. Certain papers tend to exaggerate positive effects leaving adverse events out of attention. Therefore, conclusions are partly based here on theoretic considerations. There is a discrepancy between the supposed ability of exogenous stem cells to migrate and engraft in tissues, differentiate along various cell lineages, and the absence of clear morphological evidence in vivo. Some papers discuss rejuvenation, replacement of senescent and damaged cells; others explain reported beneficial effects by paracrine or immunomodulating mechanisms. There are no prima facie reasons to assume that paracrine functions are more developed in morphologically primitive SC than in more mature cells. Stem cells are a promising field of research; however, studies of differentiated cells and cell-free products mimicking paracrine effects of cell therapies may be promising as well. Obviously, therapeutic methods with unproven effects should be applied within the framework of sound research shielded from the funding bias.