Dataset Information

Reciprocal interactions of mouse bone marrow-derived mesenchymal stem cells and BV2 microglia after lipopolysaccharide stimulation.

ABSTRACT:

Introduction

Mesenchymal stem cells (MSCs) are immunosuppressive, but we lack an understanding of how these adult stem cells are in turn affected by immune cells and the surrounding tissue environment. As MSCs have stromal functions and exhibit great plasticity, the influence of an inflamed microenvironment on their responses is important to determine. MSCs downregulate microglial inflammatory responses, and here we describe the mutual effects of coculturing mouse bone marrow MSCs with BV2 microglia in a lipopolysaccharide (LPS) inflammatory paradigm.

Methods

Mouse MSCs were cultured from femoral and tibial bone marrow aspirates and characterized. MSCs were cocultured with BV2 microglia at four seeding-density ratios (1:0.2, 1:0.1, 1:0.02, and 1:0.01 (BV2/MSC)), and stimulated with 1 μg/ml LPS. In certain assays, MSCs were separated from BV2 cells with a cell-culture insert to determine the influence of soluble factors on downstream responses. Inflammatory mediators including nitric oxide (NO), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and chemokine (C-C motif) ligand 2 (CCL2) were measured in cocultures, and MSC and BV2 chemotactic ability determined by migration assays.

Results

We demonstrated MSCs to increase expression of NO and IL-6 and decrease TNF-α in LPS-treated cocultures. These effects are differentially mediated by soluble factors and cell-to-cell contact. In response to an LPS stimulus, MSCs display distinct behaviors, including expressing IL-6 and very high levels of the chemokine CCL2. Microglia increase their migration almost fourfold in the presence of LPS, and interestingly, MSCs provide an equal impetus for microglia locomotion. MSCs do not migrate toward LPS but migrate toward microglia, with their chemotaxis increasing when microglia are activated. Similarly, MSCs do not produce NO when exposed to LPS, but secrete large amounts when exposed to soluble factors from activated microglia. This demonstrates that certain phenotypic changes of MSCs are governed by inflammatory microglia, and not by the inflammatory stimulus. Nonetheless, LPS appears to "prime" the NO-secretory effects of MSCs, as prior treatment with LPS triggers a bigger NO response from MSCs after exposure to microglial soluble factors.

Conclusions

These effects demonstrate the multifaceted and reciprocal interactions of MSCs and microglia within an inflammatory milieu.

SUBMITTER: Rahmat Z

PROVIDER: S-EPMC3706938 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Lung diseases such as acute respiratory distress syndrome (ARDS) have a high incidence worldwide. The current drug therapies for ARDS have supportive effects, making them inefficient. New methods such as stromal cell therapy are needed for this problem. METHODS:This research was performed with ten New Zealand rabbits in two groups. Bone marrow aspiration was performed on the treated group, and mesenchymal stem cells were isolated and cultured. The experimental model of ARDS was induced using LPS from Escherichia coli strain O55:B5. Then, 1010 bone marrow mesenchymal stem cells (BM-MSCs) were autologously transplanted intrapulmonary in the treatment group, and 1-2?ml of PBS in the control group. The clinical signs, computed tomographic (CT) scans, echocardiography, blood gas analysis, complete blood count, and cytokine levels were measured before and at 3, 6, 12, 24, 48, 72, and 168?h after BM-MSC transplant. Finally, the rabbits were killed, and histopathological examination was performed. RESULTS:The results showed that BM-MSCs decreased the severity of clinical symptoms, the number of white blood cells and heterophils in the blood, the total cell count, and number of heterophils and macrophages in bronchoalveolar lavage, and balanced the values of arterial blood gases (increase in partial pressure of oxygen and O2 saturation and decrease in the partial pressure of carbon dioxide). They also downregulated the tumor necrosis factor (TNF)-? and interleukin (IL)-6 concentrations and increased the IL-10 concentrations at different times compared with time 0 and in the control group, significantly. In the CT scan, a significant decrease in the Hounsfield units and total lung volume was found by echocardiography, and in comparing the two groups, a significant difference in the parameters was noticed. The histopathology demonstrated that the BM-MSCs were able to reduce the infiltration of inflammatory cells and pulmonary hemorrhage and edema. CONCLUSIONS:This study indicated that BM-MSCs play a significant role in the repair of lung injury.