A primary goal is to distinguish mechanical and morphological signals affecting macrophage mechanobiology at the cellular level in 2D and 3D. Changes in macrophages often relate to their mechanical behavior, indicating cytoskeletal dynamics, morphology, and adhesion modifications. We employed polyacrylamide gels with variable stiffness to investigate cytokine secretion, degradation, and uptake responses to differentiate mechanical stimuli from cellular characteristics across activation states. Through AFM measurements at the single-cell level, we found that the activation state of primary human macrophages influences their mechanical properties, including stiffness and viscosity. We also analyzed how mechanical environment variations impacted cellular mechanics and functions. Force spectroscopy showed that cells on low-stiffness substrates were stiffer than those on high-stiffness ones, significantly affecting macrophage phenotype as confirmed by qPCR. These results so far underline that macrophages respond to their mechanical environment. The next step will be to combine changes in the mechanical environment with cell morphological and biochemical signals to identify dominant pathways.
The second key goal is to address macrophage-driven tissue regeneration affected by transient mechanical loads. We concentrate on the functional outcomes arising from alterations in cell mechanics and morphology due to these dynamic loads. At the cellular level, we developed effective culture methods for foreign body giant cells (FBGCs) derived from human peripheral blood and characterized their properties. Following the establishment of FBGC culture methods, we subjected these cells to cyclic stretch to examine their functional responses regarding cytokine secretion, trophic factors, and degradative factors, including reactive oxygen species.
To translate the findings regarding macrophage mechanobiology at the fundamental level to an application, we developed a multi-scale computational model for macrophage-driven tissue regeneration, focusing on regenerative heart valves as a critical application. We have used a computational approach to characterize the mechanical environment in heart valve tissue engineering. The computed stresses and strains were correlated with local expression levels of immunohistochemical markers. Data collected from implants and explants in our previous one-year in vivo study showed a significant correlation between stresses, strains, and immunohistochemical markers, underlining the relevance of the work in an application.
