Macrophage-Mediated Bone Formation in Scaffolds Modified With MSC-Derived Extracellular Matrix Is Dependent on the Migration Inhibitory Factor Signaling Pathway

Abstract

The positive role of macrophages in the osteogenesis of mesenchymal stem cells (MSCs) has been a recent research focus. On the other hand, MSCs could carefully regulate the paracrine molecules derived from macrophages. Human umbilical cord mesenchymal stem cells (hucMSCs) can reduce the secretion of inflammatory factors from macrophages to improve injury healing. hucMSC-derived extracellular matrix (hucMSC-ECM) has the similar effect to hucMSCs, which could combat the inflammatory response of macrophages. Additionally, MSC-derived extracellular matrix also enhanced bone regeneration by inhibiting osteoclastic differentiation of monocyte/macrophage lineage. However, whether hucMSC-ECM could improve bone formation by guiding macrophage-induced osteogenic differentiation of MSCs is unknown. Here, we present decalcified bone scaffolds modified by hucMSC-derived extracellular matrix (DBM-ECM), which maintained multiple soluble cytokines from hucMSCs, including macrophage migration inhibitory factor (MIF). Compared with DBM, the DBM-ECM scaffolds induced bone formation in an improved heterotopic ossification model of severe combined immunodeficiency (SCID) mice in a macrophage-dependent manner. Macrophages cocultured with DBM-ECM expressed four osteoinductive cytokines (BMP2, FGF2, TGFβ3 and OSM), which were screened out by RNA sequencing and measured by qPCR and western blot. The conditioned medium from macrophages cocultured with DBM-ECM improved the osteogenic differentiation of hBMSCs. Furthermore, DBM-ECM activated CD74/CD44 (the typical MIF receptors) signal transduction in macrophages, including phosphorylation of P38 and dephosphorylation of c-jun. On the other side, the inhibitory effects of the DBM-ECM scaffolds with a deficient of MIF on osteogenesis in vitro and in vivo revealed that macrophage-mediated osteogenesis depended on MIF/CD74 signal transduction. The results of this study indicate that the coordinated crosstalk of macrophages and MSCs plays a key role on bone regeneration, with an emphasis on hucMSC-ECM constructing a macrophage-derived osteoinductive microenvironment.

Stem Cell Membrane‐Coated Microribbon Scaffolds Induce Regenerative Innate and Adaptive Immune Responses in a Critical‐Size Cranial Bone Defect Model

“…Consistent with flow cytometry results, both PD-L1 and TNFL6 were detected in MSCM, with primed MSCM exhibiting higher expression level than naïve MSCM (Figure 1e). In addition to PD-L1 and TNFL6, other immunomodulatory molecules were detected including galectin (Gal)-1/Gal-3/Gal-9, [29,30] macrophage migration inhibitory factor (MIF) [31] and transforming growth factor beta-1 (TGFB1). [32] These signals are known for inducing M2 Mϕ polarization, Treg differentiation, and cytotoxic T cell apoptosis.…”

Extracellular Vesicles Derived from Primed Mesenchymal Stromal Cells Loaded on Biphasic Calcium Phosphate Biomaterial Exhibit Enhanced Macrophage Polarization

“…In using macrophage as models of in vitro inflammation and healing processes, it is important to highlight that most of the previous studies that evaluated MSC-macrophage interactions included either macrophages of animal origin (most commonly bone-marrowderived or murine cell lines from mice, e.g., RAW 264.7 and J774A.1 [60], or human macrophage cell lines, e.g., U937 and THP-1 [61]). However, all human macrophage cell lines being tumor-derived (transformed cells), and macrophages of animal origin may not accurately represent the M1/M2 switch that is prevalent in healthy human macrophages.…”

Hypoxic Extracellular Matrix Preserves Its Competence after Expansion of Human MSCs under Physiological Hypoxia In Vitro

“…The cytokines involved in intercellular signaling in the bone marrow niche, such as angiopoietin-1, SDF-1, IL-8, VEGF, and HGF, were elevated in comparison with MSC/HSPC co-cultures on standard culture plastic [49]. The conditioned medium of macrophages on MSC-derived ECM contained elevated levels of BMP2, FGF2, and TGFβ3 and stimulated the osteogenic differentiation of MSCs [50].…”