The antimicrobial properties of stimulated and unstimulated equine mesenchymal stromal cells in vitro

Antimicrobial resistance is a growing concern, resulting in loss of life and negative societal impacts. Mesenchymal stromal cells (MSCs) are a novel antimicrobial agent, but further research is required to investigate ideal sources and priming conditions that promote antimicrobial activity. MSCs were co-cultured with E. coli and S. aureus and further stimulated with Polyinosinic:polycytidylic acid (Poly I:C) or lipopolysaccharide (LPS) to assess antimicrobial efficacy. mRNA from unstimulated and stimulated MSCs was assessed for differences in antimicrobial peptide (AMP) expression. Furthermore, MSCs were co-cultured with antimicrobials to investigate synergistic effects against Methicillin resistant S. aureus (MRSA) and resistant E. coli. Although constitutive expression of AMP genes was identified in MSCs, no significant reductions in bacterial growth or minimum inhibitory concentration were found when compared to a DMEM control. Poly I:C or LPS stimulation similarly failed to modulate mRNA expression. Further studies are necessary to investigate the in vivo potential of MSCs.