| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Biomaterial Surfaces & Interfaces | Tuesday Sessions |
| Session BI-TuE |
| Session: | Medical Applications |
| Presenter: | Alex Chen, University of Washington, USA |
| Authors: | A. Chen, University of Washington, USA B.D. Ratner, University of Washington, USA |
| Correspondent: | Click to Email |
Introduction: The polarization of macrophages is highly influential in modulating the foreign body response. Macrophages characterized by the M2 (anti-inflammatory) phenotype are believed to reduce the formation of the foreign body capsule. It is hypothesized that surface immobilizing M2 promoting bioactive molecules will reduce the formation of the foreign body capsule by increasing M2 polarization as well as decreasing M1(inflammatory) polarization of macrophages. Collagen VI (col6) and α-1 acid glycoprotein (AGP) have been shown to induce M2 polarization of macrophages when introduced in solution. This work demonstrates the feasibility of modulating macrophage polarization via immobilization of col6 and AGP onto hydrogel coated surfaces.
Methods: 2-hydroxyethyl methacrylate (HEMA) was plasma deposited onto 10mm circular glass slides. HEMA coated glass slides were washed three times in p-dioxane and then surface activated by incubation with 100mM carbonyl diimidazole (CDI) in dioxane for 2.5 hours at 40°C. CDI activated glass slides were then incubated in either 440μg/mL AGP only or 250μg/mL AGP plus 62.5 μg/mL col6 solutions in pH 10.2 sodium carbonate/bicarbonate buffer for 24 hours at 40°C. Bone marrow derived macrophages (BMDMs) were cultured by harvesting marrow from the femurs of sacrificed mice, which was then dispersed and cultured in RPMI with macrophage colony stimulating factor for 7 days. BMDMs were then transferred to glass slides coated with immobilized bioactive molecules and cultured for 48 hours. CDI activated HEMA coated glass slides without immobilized bioactive molecules was used as a control. Macrophage polarization was assessed via ELISA measurements of tumor necrosis factor-α (TNF-α), a cytokine released by M1 macrophages, as well as RT-qPCR of arginase 1 (Arg1), an enzyme highly expressed by M2 macrophages. ELISA experiments involved the addition of 10uM lipopolysaccharide(LPS) to culture media in order to induce an M1 polarization of macrophages. RT-qPCR experiments did not involve the use of LPS and solely focused on the expression of Arg1.
Results and Conclusions: ELISA experiments showed a decrease of TNF-α expression in macrophages cultured on surfaces with immobilized AGP (~30%). RT-qPCR experiments showed an increase in Arg1 expression of macrophages cultured on surfaces with immobilized AGP (2.6x) or immobilized AGP + col6 (5.85x).These experiments show the potential of using immobilized bioactive molecules to modulate the polarization of macrophages, which can potentially be used to reduce the foreign body response and foreign body capsule formation.