Novel Strategy to Enhance Human Mesenchymal Stromal Cell Immunosuppression: Harnessing Interferon-Gamma Presentation in Metal–Organic Frameworks Embedded on Heparin/Collagen Multilayers

The immunomodulatory potential of human mesenchymal stromal cells (hMSCs) can be boosted when exposed to interferon-gamma (IFN-γ). While pretreating hMSCs with IFN-γ is a common practice to enhance their immunomodulatory effects, the challenge lies in maintaining a continuous IFN-γ presence within cellular environments. Therefore, in this research, we investigate the sustainable presence of IFN-γ in the cell culture medium by immobilizing it in water-stable metal-organic frameworks (MOFs) [PCN-333(Fe)]. The immobilized IFN-γ in MOFs was coated on top of multilayers composed of combinations of heparin (HEP) and collagen (COL) that were used as a bioactive surface. Multilayers were created by using a layer-by-layer assembly technique, with the final layer alternating between collagen (COL) and heparin (HEP). We evaluated the viability, differentiation, and immunomodulatory activity of hMSCs cultured on (HEP/COL) coated with immobilized IFN-γ in MOFs after 3 and 6 days of culture. Cell viability, compared to tissue culture plastic, was not affected by immobilized IFN-γ in MOFs when they were coated on (HEP/COL) multilayers. We also verified that the osteogenic and adipogenic differentiation of the hMSCs remained unchanged. The immunomodulatory activity of hMSCs was evaluated by examining the expression of indoleamine 2,3-dioxygenase (IDO) and 11 essential immunomodulatory markers. After 6 days of culture, IDO expression and the expression of 11 immunomodulatory markers were higher in (HEP/COL) coated with immobilized IFN-γ in MOFs. Overall, (HEP/COL) multilayers coated with immobilized IFN-γ in MOFs provide a sustained presentation of cytokines to potentiate the hMSC immunomodulatory activity.