Microfluidic Device used for the Secretion of Inflammatory Cytokines from Human Monocyte-Derived Macrophages Stimulated by Ultra-High Molecular Weight Polyethylene Particles

Abstract The cause of osteolysis and aseptic loosening in a hard-on-polymer artificial joint is attributed to the discharge of micron- or submicron-sized fine polyethylene wear particles. The latter stimulate ELISA: enzyme-linked immunosorbent assay; FBS: fetal bovine serum; HMDM: Human monocyte-derived macrophage; IL: Interleukin; MEMS: microelectromechanical system; PDMS: polydimethylsiloxane; TNF: Tumour necrosis factor; UHMWPE: ultra-high molecular weight polyethylene; UV: ultraviolet macrophage activity and promote the secretion of cytokines. In general assay procedures, the macrophages with the polyethylene particles are cultured in well plates, and the culture supernatants are used for the measurement of cytokines based on an enzyme-linked immunosorbent assay. For reproducing the periprosthetic environment in in vitro experiments, a culture environment capable of reducing the physical distance between the macrophage and polyethylene particle by means of a microfluidic device comprising a narrow 200 × 500 μm flow channel is proposed and verified by performing a sequence of reliability verification tests. The culture media with macrophages were prepared and injected into the microfluidic device (5.0 × 104 cells/device). The macrophages in the microfluidic device were cultured for 48 h in an incubator at 37 °C. After the incubation, the culture medium mixed with the polyethylene particles was injected into the microfluidic device at the rate of 0.25 ml/h for 4 h (5.0 × 104 particles/device, total volume of 1 ml). The culture medium was collected, and an enzyme-linked immunosorbent assay was performed to investigate the production of cytokines. Despite the smaller volume of the culture media mixed with polyethylene particles than those used in conventional well plates, the secretions of tumour necrosis factor (TNF) -α and interleukin (IL)-6 were still confirmed. These were correlated with the polyethylene particles of sizes