Antimicrobial effects of mesenchymal stem cells primed by modified LPS on bacterial clearance in sepsis

Mesenchymal stem cells (MSCs)-based regenerative therapy is now considered as an alternative approach to revive infectious diseases, including sepsis. Nevertheless, the efficiency of MSC application is limited by the poor survival rate of engrafted MSCs. Hence, preconditioning was established as a strategy to increase the cells' efficiency.

MSCs were preconditioned with 1 μg/ml of three different lipopolysaccharides (LPSs) of Pseudomonas (Pse-LPS), Acinetobacter (Ac-LPS), and Acinetobacter inactivated lipid A by PagL (Ac-LPS-PagL). Then, preconditioned MSCs were exposed to oxidative stress and serum deprivation followed by evaluation of the antibacterial activity, survival, and apoptosis of MSCs. Then, the murine sepsis model treated with 100 μl phosphate-buffered saline (control group, sepsis group), 100 μl of 1 × 10 6 wild MSCs (MSC group), and three remained groups received 100 μl of 1 × 10 6 LPS-preconditioned MSCs (Pse-LPS-MSCs group: LPS purified from Pseudomonas, or Ac-LPS-MSCs group: LPS purified from Acinetobacter, and Ac-PagL-LPS-MSCs group: detoxified LPS Pagl).

After 4 days, LPS-preconditioned MSC transplantation modulated the immune response and reduced inflammation in septic mice. Apoptosis of Pse-LPS/Ac-LPS-preconditioned-MSCs was obviously reduced in vitro, and the survival rate of engrafted mice was evidently elevated in Pse-LPS-MSCs and Ac-LPS-MSCs groups compared with other three groups.

LPS preconditioning provides an innovative strategy for evolving functional and biological properties of MSCs and ameliorates the survival rate of the mouse model of sepsis after MSC transplantation, protects cells from apoptosis and organ damages, and evaluates therapeutic properties, including immunemodulatory.