Mesenchymal stromal cells: An emerging cell-based pharmaceutical

Abstract

Over the course of the last decade, mesenchymal stromal cells (MSC) made a remarkable entry into the field of cellular therapy. Their ability to differentiate into several mesenchymal lineages, as well as their role in hematopoiesis, provided the basis for several clinical investigations in the field of regenerative medicine, ranging from heart repair to hematopoietic support in patients undergoing hematopoietic peripheral blood progenitor cells transplantation. In addition, MSC were also shown to modulate the immune response, either by acting as an immunosuppressant on several immune cells (T and B cells, dendritic cells, and macrophages), or on IFN-γ stimulation, as antigen presenting cells (APC) for the priming of CD4+ and CD8+ T cells. Although the exact mechanisms by which MSC mediate their immunosuppressive effect is not fully elucidated, several in vivo results from animal disease models and clinical trials in humans has proven the potential of MSC as immunosuppressive as well as anti-inflammatory agents. Conversely, MSC can also stimulate the immune system by presenting exogenously acquired antigen to T cells, a feature currently investigated in the context of cell-based vaccines for cancer immunotherapy. The mechanisms underlying the physiological roles and immuno-modulatory properties of MSC must, however, be clarified in order to optimize their beneficial impact while minimizing unwanted phenomena. The pre sent review hereby attempts to summarize and reflect on the latest breakthroughs concerning the elucidation of MSC properties and their clinical applications with a special attention to their role in immunotherapy.