Mechanoregulation of MSC spheroid immunomodulation

Area of Science:

• Biomedical Engineering
• Cell Biology
• Immunology

Background:

• Mesenchymal stromal cells (MSCs) are vital for regenerative medicine due to their secretome, which aids tissue repair and immune modulation.
• MSC spheroids offer enhanced viability and cytokine secretion compared to single cells.
• The impact of mechanical stimulation on MSC spheroids remains largely unexplored.

Purpose of the Study:

• To investigate the effect of controlled uniaxial cyclic compression on immunomodulatory cytokine secretion by human MSC spheroids.
• To assess how mechanical loading influences MSC mechanoresponsiveness and gene expression.
• To determine the optimal mechanical conditions for enhancing the therapeutic potential of MSC spheroids.

Main Methods:

• Human MSC spheroids were encapsulated in alginate hydrogels and subjected to three distinct cyclic compressive regimes (L5H30, L10H30, L10H250) with varying stress and hold durations.
• Cytokine and chemokine expression levels were analyzed.
• Macrophage polarization (M2 phenotype) was assessed using human THP-1 macrophages.
• F-actin organization and YAP-related gene expression were examined under different loading conditions and after disruption of the actin cytoskeleton.

Main Results:

• Mechanical loading regimes altered cytokine and chemokine expression, with higher stress inducing more pronounced changes.
• Only the L10H30 loading condition significantly induced M2 polarization in THP-1 macrophages.
• Static and L10H30 conditions promoted a stable F-actin structure, while other regimes disrupted it.
• Disruption of the actin cytoskeleton led to decreased YAP-related gene expression and reduced secretion of inflammatory cytokines.

Conclusions:

• Mechanical stimulation significantly impacts the immunomodulatory properties of MSC spheroids.
• Specific mechanical loading parameters, such as L10H30, can enhance the ability of MSC spheroids to modulate immune responses.
• Mechanosignaling pathways, particularly those involving the actin cytoskeleton and YAP, are crucial for mediating the therapeutic effects of MSC spheroids.