Introduction: Stem cells, with their potential for regeneration and differentiation, play an essential role in various stages of tissue growth and repair. Stem cells are divided into two types based on origin: embryonic and adult . Stem cells currently used in cell therapy are mature stem cells. These cells include hematopoietic stem cells (HSC), endothelial cells (EPCs), mesenchymal stem cells (MSCs), and organ-specific stem cells . MSCs have been used extensively in studies. However, the effectiveness and shelf life of MSCs are very short . Recent studies suggest that the main stimulus observed in MSC therapeutic function is paracrine agents secreted by these cells. The supernatant of the culture medium of these cells, called the conditional medium derived from MSC-CM mesenchymal stem cells, is a rich source of paracrine factors and is studied in a wide range of repair and treatment methods .
Methods: This search was performed on Scopus, PubMed databases with the keywords mesenchymal stem cell, paracrine secretion, conditional medium in the period 2015 to 2020. Out of 31 articles, 20 articles were selected and used in this study.
Results: Secretion-based approaches using conditioned media may have significant potential advantages over living cells in terms of production, storage, transport, product shelf life, and their potential as a ready-made biological therapeutic agent .
Conclusion: Despite the multipotency and self-renewal potential of MSCs, experimental studies have shown that only a small fraction of mesenchymal stem cells are systemically incorporated into damaged tissues, indicating beneficial effects in repair and tissue regeneration is indirect and depends on the paracrine activity of MSCs. Therefore, the use of MSC-CM removes the limitations of using stem cells as a therapeutic source for tissue regeneration.
Keywords: mesenchymal stem cells , conditional medium , paracrine