Peptoid‐Cross‐Linked Hydrogel Stiffness Modulates Human Mesenchymal Stromal Cell Immunoregulatory Potential in the Presence of Interferon‐Gamma

Abstract

Human mesenchymal stromal cell (hMSC) manufacturing requires the production of large numbers of therapeutically potent cells. Licensing with soluble cytokines improves hMSC therapeutic potency by enhancing secretion of immunoactive factors but typically decreases proliferative ability. Soft hydrogels, however, have shown promise for boosting immunomodulatory potential, which may compensate for decreased proliferation. Here, hydrogels were crosslinked with peptoids of different secondary structures to generate substrates of various bulk stiffness but fixed network connectivity. Secretion of interleukin 6 (IL‐6), monocyte chemoattractive protein (MCP‐1), macrophage colony‐stimulating factor (MCS‐F), and vascular endothelial growth factor (VEGF) were shown to depend on hydrogel stiffness in the presence of interferon gamma (IFN‐γ) supplementation, with soft substrates further improving secretion. The immunological function of these secreted cytokines was then investigated via coculture of hMSCs seeded on hydrogels with Primary Peripheral Blood Mononuclear Cells (PBMCs) in the presence and absence of IFN‐γ. Co‐cultures with hMSCs seeded on softer hydrogels showed decreased PBMC proliferation with IFN‐γ. To probe possible signaling pathways, immunofluorescent studies probed the NF‐κB pathway and demonstrated that IFN‐γ supplementation and softer hydrogel mechanics led to higher activation of this pathway. Overall, these studies may allow for production of more efficacious therapeutic hMSCs in the presence of IFN‐γ.This article is protected by copyright. All rights reserved