Instructing Human Macrophage Polarization by Stiffness and Glycosaminoglycan Functionalization in 3D Collagen Networks

Abstract

Dynamic alterations of composition and mechanics of the extracellular matrix are suggested to modulate cellular behavior including plasticity of macrophages (MPhs) during wound healing. In this study, engineered 3D fibrillar matrices based on naturally occurring biopolymers (collagen I, glycosaminoglycans (GAGs)) are used to mimic matrix stiffening as well as modification by sulfated and nonsulfated GAGs at different stages of wound healing. Human MPhs are found to sensitively respond to these microenvironmental cues in terms of polarization toward proinflammatory or wound healing phenotypes over 6 days in vitro. MPhs exhibit a wound healing phenotype in stiffer matrices as determined by protein and gene expression of relevant cytokines (IL10, IL12, and TNFα). Presence of sulfated and nonsulfated GAGs inhibits this polarization effect. Furthermore, control experiments on 2D matrices stress the relevance of using stiffness-controlled 3D matrices, as MPhs show a reciprocal polarization behavior depending on GAG presence. Hence, the results indicate a strong influence of dimensionality, stiffness, and GAG presence of the biomaterial scaffold on MPh polarization and emphasize the need for matrices closely mimicking the 3D in vivo context with a variable stiffness and GAG composition in in vitro studies.

Effect of nano-structural properties of biomimetic hydroxyapatite on osteoimmunomodulation

“…Moreover, no correlation was found between the stiffness of the substrates and the morphology of immune cells. In fact, the Young's modulus of the substrates seem to be too high to be sensed by immune cells, which are usually activated by stiffness values in the range of kPa [29][30][31].…”

Current Advances in Immunomodulatory Biomaterials for Bone Regeneration

“…Mouse bone marrow–derived macrophages were cultured on polydioxanone electrospun fibers with varying pore sizes, demonstrating that increased pore size favored the M2 phenotype of the macrophages, which was evident by the increased expression of Arginase 1 and decreased expression of M1 marker iNOS . Similarly, human macrophages cultured on collagen‐based matrices with varying stiffness showed that increased matrices stiffness resulted in an M2 phenotype of the macrophages …”

Biomaterials as Tools to Decode Immunity

“…This figure demonstrates 2D and 3D culture systems differentially impact immune cell function. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

“…With respect to dimensionality, one recent study used hydrogels to demonstrate how immune cells respond differently to 2D and 3D environments . These hydrogels were composed of either pure collagen gels or gels containing hyaluronic acid or high‐sulfated hyaluronan, and crosslinked with EDC.…”

“…In addition, 3D cultures preserve a porosity parameter that is present in native extracellular matrices. In this hydrogel system, macrophages responded differently to stimulus depending on whether the culture system was 2D or 3D (Figure h) …”