Microchamber-based platform for quantitative and time-resolved immune monitoring of macrophage responses to biorelevant micro- and nanoparticles (Application to ultra-high-molecular-weight polyethylene wear particles)

抄録

Wear particles generated from ultra-high-molecular-weight polyethylene (UHMWPE) joint components play a central role in macrophage-mediated inflammatory responses associated with periprosthetic osteolysis. Although particle size, material modification, and particle load are known to influence biological reactivity, the temporal dynamics of macrophage responses under continuous exposure remain insufficiently understood. In this study, a microchamber-based platform was employed to enable controlled, cumulative, and time-resolved exposure of human monocyte-derived macrophages to clinically relevant UHMWPE wear particles. Wear particles were generated under four material conditions (virgin, γ-irradiated, vitamin-E-blended, and vitamin-E-blended with γ-irradiation) and classified into two size groups enriched in particles smaller or larger than approximately 1 µm. Macrophages were continuously exposed for 24 h under two cumulative particle load conditions corresponding to approximately 5× and 40× the seeded cell number. Culture medium was collected at regular intervals and analyzed for tumor necrosis factor alpha (TNF-α) using an enzyme-linked immunosorbent assay. TNF-α production showed time-dependent changes, including transient early-phase increases followed by declines in some donor-derived macrophages. Higher cumulative particle loading generally resulted in greater TNF-α production than lower loading, indicating that cumulative particle burden influences the inflammatory response profile. In contrast, the effects of particle size and UHMWPE material modification were less distinct under the present conditions, while donor-dependent variation was evident. These findings indicate that cumulative particle load is an important determinant of macrophage inflammatory responses to UHMWPE wear particles. The microchamber-based system provides a useful experimental framework for time-resolved analysis of wear particle–cell interactions and contributes to a better understanding of the mechanisms underlying implant-related inflammation.