A shiny app to explore the characterisation of Mesenchymal Stromal Cells in clinical trial reports Prepared to support: Wilson, A. J., Rand, E., Webster, A. J., & Genever, P. G. (2021). Characterisation of mesenchymal stromal cells in clinical trial reports: analysis of published descriptors. Stem cell research & therapy, 12 (1), 360. https://doi.org/10.1186/s13287-021-02435-1 Abstract: Mesenchymal stem or stromal cells (MSCs) are the most widely used cell therapy to date. They are heterogeneous, with variations in growth potential, differentiation capacity and protein expression profile depending on tissue source and production process. Nomenclature and defining characteristics have been debated for almost 20 years, yet the generic term “MSC” is used to cover a wide range of cellular phenotypes. Against a documented lack of definition of cellular populations used in clinical trials, our study evaluated the extent of characterization of the cellular population or study drug. A literature search of clinical trials involving mesenchymal stem/stromal cells was refined to 84 papers upon application of pre-defined inclusion/exclusion criteria. Thirty-two studies (38.1%) include no characterization data whatsoever. Forty-one (48.8%) reported average values per marker for all cell lots used in the trial, and only eleven (13.1%) studies included individual values per cell lot. Viability was reported in 57% of studies. Differentiation was discussed: osteogenesis (29% of papers) adipogenesis (27%) and chondrogenesis (20%); and other functional assays arose in 6 papers (7%). Extent of characterization was not related to clinical phase of development. Assessment of functionality was very limited and did not always relate to likely mechanism of action. We discuss the potential implications of these findings for the use of MSCs in regenerative medicine, and the importance of characterization for transparency and comparability of literature.