Enforced mesenchymal stem cell tissue colonization counteracts immunopathology

Area of Science:

• Immunology
• Cell Biology
• Regenerative Medicine

Background:

• Mesenchymal stem/stromal cells (MSCs) possess immunoregulatory properties crucial for treating inflammatory diseases.
• The in vivo efficacy of MSCs is debated, particularly regarding the necessity of tissue colonization for immunomodulation.
• Acute graft-versus-host disease (aGvHD) is a severe immune complication requiring effective therapeutic strategies.

Purpose of the Study:

• To investigate if MSC tissue colonization is critical for dampening immune-mediated inflammation in vivo.
• To determine if enhancing MSC E-selectin binding improves their therapeutic potential in aGvHD.
• To elucidate the mechanisms by which MSCs exert immunomodulatory effects in situ.

Main Methods:

• Utilized a murine model of aGvHD induced by allogeneic hematopoietic stem cell transplantation.
• Engineered MSCs to express HCELL, a CD44 glycoform that binds E-selectin, to promote tissue-specific recruitment.
• Administered HCELL+ MSCs or HCELL- MSCs systemically and evaluated therapeutic outcomes and MSC localization.

Main Results:

• HCELL+ MSCs exhibited increased intercalation within inflamed tissues compared to HCELL- MSCs.
• Recipients of HCELL+ MSCs showed reduced leukocyte infiltration and lower systemic inflammatory cytokine levels.
• HCELL+ MSCs significantly improved tissue preservation and survival rates in the aGvHD model.
• MSC immunomodulatory activity was potentiated by HCELL/CD44 ligation, leading to increased IL-10 secretion.

Conclusions:

• MSCs counteract immunopathology directly within affected tissues (in situ).
• Enhancing MSC E-selectin ligand binding (HCELL/CD44) significantly boosts their immunomodulatory capacity and therapeutic efficacy.
• Targeting MSC-endothelial interactions is a promising strategy to harness their full immunobiologic potential for treating inflammatory diseases and maintaining tissue immunohomeostasis.