The use of mesenchymal stem cells (MSCs) in clinical trials has witnessed a global surge, positioning MSCs as one of the most sought-after regenerative cell types. Precision in defining these cells is crucial due to their diverse applications. Broadly characterised as multipotent stem cells with the ability to differentiate into various lineages, including osteocytes, adipocytes, and chondrocytes, the nomenclature of MSCs has undergone a fascinating evolution.

Historical Perspectives:

The roots of MSC discovery trace back to the 1970s when Friedenstein and colleagues identified a population of adherent, colony-forming, fibroblast-like cells in bone marrow. Initially named CFU-F and Osteogenic Stem cells, the nomenclature took diverse turns. In 1988, Owen and colleagues introduced “stromal stem cells,” emphasising their residence in stromal rather than hematopoietic compartments. Subsequently, Arnold Caplan coined “mesenchymal stem cells” in 1991, highlighting their self-renewal and differentiation capabilities. However, alternative terms like”mesenchymal progenitor cells,” “skeletal stem cell,” “multipotent adult progenitor cells,” and “medicinal signaling cells” emerged, challenging the consensus.

Standardisation by ISCT (2006):

Finally, in 2006, the International Society for Cellular Therapy (ISCT) proposed the term“multipotent mesenchymal stromal cells”, and provided a set of criteria to define human MSCs. These criteria include adherence to plastic in culture, expression of specific surface markers, and the ability to differentiate into osteoblasts, adipocytes, and chondrocytes.

Decoding the Names:

Mesenchymal Stem Cells

• “Mesenchymal” denotes their tissue origin, originating from mesenchyme in embryos.
• “Stem cells” highlights their capacity to differentiate into various cell types.
• Coined by Arnold Caplan in 1991 based on their capability to form mesenchymal tissues.

Multipotent Stem Cells

• Reflecting the cells’ ability to differentiate into diverse cell types.
• Notably, their differentiation potential is more limited than pluripotent stem cells.

Mesenchymal Stromal Cells

• Acknowledges the challenge of isolating ‘pure’ stem cells, often collected with non-stem cell types from stromal tissue.
• Considered by some scientists to be a more accurate term

Medicinal Signalling Cells

• Emphasises MSCs’ therapeutic potential beyond traditional stem cell roles.
• Highlights their immunomodulatory and paracrine signalling properties.

Colony-Forming Unit-Fibroblasts (CFU-F)

• Historically significant term reflecting early isolation and characterisation methods.
• Involves culturing cells to form colonies from a single progenitor cell, with”fibroblasts” referring to their spindle-shaped morphology

The journey through the nomenclature of mesenchymal stem cells unveils a rich history of discovery, debate, and consensus. From historical terms like CFU-F to the standardised “multipotent mesenchymal stromal cells,” each name reflects a facet of their biology, emphasizing their potential in regenerative medicine and beyond.

References:

• Bianco P, Gehron Robey P. Marrow stromal stem cells.J Clin Invest.2000;105(12):1663-1668. doi:10.1172/JCI10413
• Caplan AI. Mesenchymal stem cells. J Orthop Res. 1991;9(5):641-650.doi:10.1002/jor.1100090504
• Dennis JE, Merriam A, Awadallah A, Yoo JU, Johnstone B, Caplan AI. Aquadripotential mesenchymal progenitor cell isolated from the marrow of an adult mouse. J Bone Miner Res. 1999;14(5):700-709. doi:10.1359/jbmr.1999.14.5.700
• Dominici M, Le Blanc K, Mueller I, et al. Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement.Cytotherapy.2006;8(4):315-317. doi:10.1080/14653240600855905
• Friedenstein AJ, Petrakova KV, Kurolesova AI, Frolova GP. Heterotopic of bone marrow. Analysis of precursor cells for osteogenic and hematopoietic tissues.Transplantation. 1968;6(2):230-247Jiang Y,Jahagirdar BN, Reinhardt RL, et al. Pluripotency of mesenchymal stem cells derived from adult marrow [published correction appears in Nature. 2007 Jun14;447(7146):879-80].Nature. 2002;418(6893):41-49. doi:10.1038/nature00870