Fine-tuning licensing strategies to boost MSC-based immunomodulatory secretome

Area of Science:

• Cellular and Molecular Immunology
• Regenerative Medicine
• Biotechnology

Background:

• Immune-mediated inflammatory diseases (IMIDs) pose a significant global health burden with limited treatment options.
• Mesenchymal stromal cells (MSCs) and their secretome show promise for immunomodulation, but standardized protocols are lacking.
• Developing a robust immunomodulatory MSC phenotype is crucial for therapeutic advancement.

Purpose of the Study:

• To optimize the MSC-derived secretome for enhanced suppression of activated immune cells.
• To identify optimal conditions for MSC secretome production, including cytokine type, ratio, concentration, production time, and cellular confluence.
• To evaluate the impact of these factors on MSC behavior and secretome composition.

Main Methods:

• Systematic evaluation of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) effects, individually and combined.
• Optimization of cytokine ratio, concentration, production duration, and cell confluence.
• Assessment of cell behavior, viability, cytosolic content release, and secretion of key immunomodulatory factors.

Main Results:

• An optimized protocol involving overnight licensing with a 1:1 ratio of IFN-γ and TNF-α (60 ng/mL) followed by 48h incubation at 90% confluence.
• The resulting conditioned media (CM) demonstrated over twofold greater efficacy in inhibiting peripheral blood mononuclear cell (PBMC) activation compared to suboptimal protocols.
• Direct cell-cell contact was identified as essential for inducing regulatory T cells (Tregs).

Conclusions:

• A robust and standardized protocol for mesenchymal stromal cell (MSC) licensing has been established.
• This optimized protocol significantly enhances the immunomodulatory properties of the MSC secretome.
• The findings pave the way for developing novel and effective therapies against immune-mediated inflammatory diseases (IMIDs).