Regulation of Macrophage Behavior by Chitosan Scaffolds with Different Elastic Modulus

Increasing evidence shows that the physical properties of biomaterials play an important role in regulating cell behavior and function, especially the mechanical properties of biomaterials. Macrophages can also be multidirectionally regulated by mechanical factors in the microenvironment, which simultaneously mediate biomaterials response that triggered by foreign body reactions (FBR). However, how the stiffness of biomaterials regulates macrophages and the underlying mechanisms are still not well understood. Our study demonstrates that chitosan freeze-dried scaffolds with different elastic modulus can modulate the proliferative capacity, growth morphology and polarization behavior of macrophages. The compression tests and morphology observation confirmed that the prepared lyophilized chitosan scaffolds possessed varied stiffness. The fluorescence staining experiments showed that the RAW macrophage cell lines exhibited differences in proliferation and morphology on the freeze-dried scaffolds with different stiffness. Macrophages in the 5% group (elastic modulus of 106.7 kPa) had the largest number and mean cell area. Furthermore, ELISA and qPCR results illustrated that macrophage polarization towards the M1/M2 phenotype was strongly influenced by the stiffness of the lyophilized scaffolds. The study may provide new insights and references for designing the elastic moduli of biomaterials for regulating immune responsiveness.