Mesenchymal Stem Cells: Time to Change the Name!

TLDR

Mesenchymal stem cells (MSCs), defined over 25 years ago as bone‑marrow–derived cells capable of differentiating into mesodermal tissues, have been used as a multipotent assay that spurred biotech companies, yet today most clinical trials focus on their therapeutic use rather than their in‑vitro multipotentiality. The authors propose renaming MSCs to Medicinal Signaling Cells to better reflect their role as in‑situ therapeutic factor producers. MSC therapeutic action relies on homing to injury sites and secreting immunomodulatory, trophic factors that activate resident stem cells for tissue repair. The term “stem cell” misleads patients into expecting direct tissue regeneration, whereas MSCs actually function as medicinal signaling cells that modulate.

Abstract

Summary Mesenchymal stem cells (MSCs) were officially named more than 25 years ago to represent a class of cells from human and mammalian bone marrow and periosteum that could be isolated and expanded in culture while maintaining their in vitro capacity to be induced to form a variety of mesodermal phenotypes and tissues. The in vitro capacity to form bone, cartilage, fat, etc., became an assay for identifying this class of multipotent cells and around which several companies were formed in the 1990s to medically exploit the regenerative capabilities of MSCs. Today, there are hundreds of clinics and hundreds of clinical trials using human MSCs with very few, if any, focusing on the in vitro multipotential capacities of these cells. Unfortunately, the fact that MSCs are called “stem cells” is being used to infer that patients will receive direct medical benefit, because they imagine that these cells will differentiate into regenerating tissue-producing cells. Such a stem cell treatment will presumably cure the patient of their medically relevant difficulties ranging from osteoarthritic (bone-on-bone) knees to various neurological maladies including dementia. I now urge that we change the name of MSCs to Medicinal Signaling Cells to more accurately reflect the fact that these cells home in on sites of injury or disease and secrete bioactive factors that are immunomodulatory and trophic (regenerative) meaning that these cells make therapeutic drugs in situ that are medicinal. It is, indeed, the patient's own site-specific and tissue-specific resident stem cells that construct the new tissue as stimulated by the bioactive factors secreted by the exogenously supplied MSCs.