Rat BMSC infusion was unable to ameliorate inflammatory injuries in tissues of mice with LPS-induced endotoxemia

Abstract

Background:

Mesenchymal stem cells (MSC) have been shown to have potent immunoregulatory effects. They are able to mitigate inflammation in many contexts of immune disorders, including autoimmune diseases and graft-versus-host disease (GVHD). Endotoxemia can induce systematic inflammation in the body. In this study, we try to investigate whether MSC can attenuate inflammation in models of LPS-induced endotoxemia.

Methods:

Bone marrow MSC (BMSC) were isolated and expanded from rats of 4∼6-week age. Adult mice were divided randomly into Control group, Model group and BMSC group. LPS were injected peritoneally into mice of Model group and BMSC group to induce endotoxemia. For BMSC group mice, $1\times {10}^6$ BMSC were injected through tail vein 1 hour after LPS application. Animals were sacrificed after 24 hours. Inflammatory damage in lungs and livers were detected through histochemistry. Wet/dry ratio of lung tissues was calculated, levels of inflammatory factors as IL-1β and TNF-α in lung tissues were measured through ELISA.

Results:

Inflammatory pathological changes in lung and liver in BMSC group were comparable to those in Model group. Moreover, in some animals, the injuries were exacerbated after BMSC treatment. Accordingly, wet/dry ratio of lung in BMSC group mice was higher than that in Model group mice. IL-1β level in BMSC-treated group mice was significantly augmented, however, no significant changes were detected between these two groups for level of TNF-α.

Conclusion:

Our results showed that application of BMSC in LPS-induced endotoxemia models couldn’t attenuate the inflammatory injuries in tissues. Although BMSC have been shown to be able to induce immune inhibition, however, in some instances, their immuno-inhibitory function might be regulated by the local environment.