Definition and Characteristics of Mesenchymal Stromal Cells in Preclinical and Clinical Studies: A Scoping Review

Abstract

Mesenchymal stromal cells (MSCs) are widely used in preclinical and clinical research. Despite minimal criteria to define MSCs provided by the International Society for Cell and Gene Therapy (ISCT), concerns have been raised about inconsistent descriptions of cell products used. To address the question "How are MSCs currently defined and characterized?" we conducted a scoping review on original MSC preclinical and clinical studies published over a 3-month period. Selected studies identified from a systematic search of MEDLINE and Embase were categorized as follows: Clinical, Animal, Biology, or Biomaterial studies. Data were extracted from a randomly selected subsample of studies. We extracted information, including epidemiological characteristics of studies, study design, ISCT criteria, and MSC characterization and culture condition. A total of 1053 articles were included and among them, 318 articles were analyzed. Overall, 18% of the articles explicitly referred to the ISCT minimal criteria for MSC. MSC characteristics and culture conditions were inconstantly reported (eg, viability assay reported in only 18% of the articles). Only 20% of documents reported at least 1 functional assay. Clinical studies showed inconsistent completeness in reporting relevant information on the MSC characterization and cell manufacturing processes. These results suggest that further development and implementation of a consensus definition of MSCs and reporting guidelines are needed to enhance rigor, reproducibility, and transparency in MSC research.

Keywords: MSC characteristics; MSC definition; clinical studies; mesenchymal stromal cell; preclinical; scoping review.

Graphical Abstract

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.

Figure 2.

Reported International Society for Cell and Gene Therapy (ISCT) minimal criteria for mesenchymal stromal cells (MSC). This graph shows, for each study category, the percentage of studies reporting the criterion. The criterion “refer to ISCT criteria” refers to the number of studies where the authors stated that they were using the ISCT criteria.

Figure 3.

Reported mesenchymal stromal cells (MSC) characteristics and culture condition. For MSC characteristics, the following items were assessed: MSC source (eg, patient, donor, commercial), MSC fitness (fresh or cryopreserved MSC), viability assessment prior to MSC use. For culture condition, the following items were assessed: number of cell passages prior to cell use/administration, cell confluence before cell harvest, oxygen (O₂) condition for culture (5% vs. 21% of oxygen), type of medium, and serum use.