Membrane particles generated from mesenchymal stromal cell modulate immune responses by selective targeting proinflammatory monocytes

A. Merino, F. Goncalves, F. Luk, S.S. Korevaar, A. Paz, C. Lopez-Iglesias, C.C. Baan, M.J. Hoogduijn

Thursday 15 march 2018

15:30 - 15:35h at Willem Burger Foyer

Categories: Basic, Session (poster)

Parallel session: Poster session 4: Basic/translational research

Background

Multiple clinical trials in kidney transplantation have been conducted with Mesenchymal Stromal Cells (MSC) due to their immunomodulatory capacity. However, culture expanded MSC are large and get trapped in the capillary networks of the lungs after intravenous infusion, where they have a short survival time. Hypothetically, living cells are a risk for tumor formation. To reduce risks associated with MSC infusion and improve the distribution in the body, we propose to generate nano-membrane particles (MP) from MSC and MSC stimulated with IFN-γ (MPγ).

Aim

To generate and characterize Membrane Particles derived from MSC cultured with and without IFN-γ, analyze their immunomodulatory properties, and their interaction with the immune system.

Methods

Adipose tissue mesenchymal stromal cells were treated with and without IFN-γ (50ng/ml-72h). Membrane Particles from both type of cells (with/without IFN-γ) were generated by hypotonic shock and extrusion. The characterization of the Membrane Particles was performed by nanosight, and electron microscopy. Peripheral blood mononuclear cells were treated with various concentrations of Membrane Particles, and expression of immune markers was analysed by PCR. Lymphocyte proliferation and monocyte apoptosis were performed by flow cytometry, and the interaction of membrane particles with the immune cells by confocal microscopy.

Results

Tracking analysis and electron microscopy indicated that the average size of Membrane Particles was 120 nm, and they showed a round shape. Membrane Particles exhibited ATPase, and nucleotidase activity, indicating they are enzymatically active. Membrane Particles from both type of cells (with/without IFN-γ) did not physically interact with T cells and had no effect on CD4⁺ and CD8⁺ T cells proliferation. However, both Membrane Particles selectively bound to monocytes and decreased the frequency of pro-inflammatory CD14⁺CD16⁺ monocytes by induction of selective apoptosis. Membrane Particles from IFN treated MSC but not from control MSC increased the percentage of anti-inflammatory PD-L1 monocytes. The confocal microscopy analysis showed that Membrane Particles were bounded to the plasma membrane of the monocytes but they were not internalized.

Conclusion

These data demonstrate that Membrane Particles have immunomodulatory properties and have potential as a novel cell-free therapy for treatment of immunological disorders.