Abstract

Mesenchymal stem cells (MSCs) are prevalent within the human body and can be detected and isolated from nearly all tissues. The acronym MSCs is widely recognized as referring to adult stem cells with multipotent capabilities. Despite over 40 years of applications in research and clinical settings, the definition of MSCs as mesenchymal stem cells has faced scrutiny concerning their "stemness" and the underlying mechanisms of their therapeutic effects. In 2010, Dr. Arnold I. Caplan suggested redefining MSCs as "medicinal signaling cells" rather than mesenchymal stem cells. In this commentary, I concur with Dr. Caplan's view but further propose that MSCs be regarded as "master signaling cells." The primary therapeutic mechanism of MSCs is their signaling function. They respond to signals from immune cells to become activated and, in turn, act as signaling regulators for other cells. As master signaling cells, MSCs are multipotent stem cells present in almost all tissues, playing vital roles in regulating tissue homeostasis and facilitating tissue regeneration.