A historical overview and concepts of mesenchymal stem cells

Abstract

Mesenchymal stem cells have generated great interest among researchers and physicians due to their unique biological characteristics and potential clinical applications. Here, we first give a brief introduction to mesenchymal stem cells, from their discovery to their definition, sources and types. During embryonic development, MSCs arise from two major sources: neural crest and mesoderm. We discuss these two developmental origins. Additionally, we propose for the first time the concept of a hierarchical system of MSCs and draw the conclusion that post-embryonic subtotipotent stem cells are cells that are leftover from embryonic development and are at the top of the hierarchy, serving as a source of MSCs. Then, we describe various concepts related to MSCs, such as their plasticity, immunomodulatory functions, homing and secretion of bioactive molecules. These concepts constitute an important part of the biological properties of MSCs, and a thorough understanding of these concepts can help researchers gain better insight into MSCs. Finally, we provide an overview of the recent clinical findings related to MSC therapeutic effects. MSC-based clinical trials have been conducted for at least 12 types of pathological conditions, with many completed trials demonstrating their safety and efficacy.