Quality control and immunomodulatory potential for clinical-grade equine bone marrow-derived mesenchymal stromal cells and conditioned medium.

This research investigated the safety and potential for use of equine bone marrow-derived mesenchymal stromal cells (BMMSCs) and their conditioned medium (CM) in cell therapy, with particular emphasis on controlling quality and understanding the cells’ innocuousness and immunompressive capabilities.

Cell Characterization and Quality Control

• The team started by conducting an immunophenotypic characterization of equine BMMSCs. Using flow cytometry and markers such as CD90, CD19, CD14, CD105, CD45, and HLA-DR, the team sought to obtain a detailed characterization these cells.
• Note that flow cytometry is an important scientific technique used to measure the physical and biochemical characteristics of a population of cells. It revealed that all BMMSC populations isolated from animals displayed high expression of CD90 and CD105 (markers typically associated with MSCs), and low expression of CD19, CD4, CD45, and HLA-DR (markers associated with other types of cells).
• Moreover, they conducted a GTG banding cytogenetic analysis in order to evaluate the chromosomal stability of the BMMSCs. Of the 60 metaphases analyzed, only 5% showed aneuploidy (an abnormal number of chromosomes), which reveals a generally satisfying stability in the populations of cells.
• Lastly, the researchers examined the microbiological quality of the BMMSCs using 4 test samples and confirmed there was no bacterial or fungal contamination.

Immunomodulatory Potential

• The team then assessed the immunomodulatory capabilities of both BMMSCs and their conditioned medium (CM). The CM consists of the medium that cells have been grown in, which contains various factors secreted by the cells.
• This was investigated using an in vitro lymphocyte inhibition assay. Lymphocytes are type of white blood cells that are key players in the immune system.
• Therefore, the ability of BMMSCs and CM to significantly inhibit lymphocyte proliferation (i.e., block their multiplication) highlights a strong immunosuppressive potential. This was particularly seen when these were compared to the phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs).

Implications and Conclusion

• This study validates equine BMMSCs and their CM as potentially effective therapeutic interventions for inflammatory diseases. The evidence suggests they meet the necessary safety requirements and display a strong capacity for suppressing inappropriate immune responses.
• Notably, the techniques used in this study were effective for assessing and guaranteeing the quality of BMMSCs, highlighting the minimum criteria for the clinical use of BMMSCs in veterinary medicine.