Increased internalization of Staphylococcus aureus and cytokine expression in human Wharton's jelly mesenchymal stem cells.

BACKGROUND

Although a large number of studies have documented the interaction of mesenchymal stem cells (MSCs) with cells of both the innate and adaptive immune systems, not much is known about how bacteria interact with MSCs and how this might influence MSCs behavior. In this study, we investigated the impact of Staphylococcus aureus (S. aureus), on viability and cytokines' production of human Wharton's jelly-MSCs (WJ-MSCs).

OBJECTIVE

To investigate if WJ-MSCs: (1) internalize S. aureus; (2) are able to survive and (3) release immunomodulatory mediators after interaction with S. aureus.

METHODS

WJ-MSCs were exposed to S. aureus at a multiplicity of infection (MOI) of 10:1 or 30:1 for different designed times. After interaction, intracellular bacteria were quantified as well as MSCs viability. Expression and cytokine-secretion were assessed using quantitative real-time PCR and ELISA.

RESULTS

We found that the challenge of WJ-MSCs with S. aureus resulted in increased internalization of S. aureus in a time-dependent manner until six hours post-infection at either MOI of 10:1 and 30:1 and in increased expression of IL-6 mRNA and secretion of TNF-α at six hours and nine hours post-infection (p<0.05).

CONCLUSIONS

These results indicate that WJ-MSCs are able to internalize S. aureus and reveal a potential important function of these cells in the immune response.