Fig. 1.

Design and characterization of backpack-carrying monocytes. (A) Schematic of backpack (BP) design, including dexamethasone and IL-4 loading and anti-CD45 F(ab′) functionalization. (B) Schematic of backpack attachment to primary monocytes. (C) Percentage of monocytes with >1 backpack (determined by flow cytometry); mean ± SD (n = 3). Representative flow cytometry gating of control monocytes vs. backpack-adhered monocytes. (D) Confocal micrograph of monocyte (membrane: green, nucleus: blue) with backpack (red). (Scale bar, 5 µm.) (E) Percentage of monocytes with backpacks attached following shear studies (determined by flow cytometry); mean ± SD (n = 3 to 4). (F) Percentage of live cells at 1 h and 24 h for monocytes (Mo.) and backpack-monocytes (BP-Mo.) (determined by flow cytometry); mean ± SD (n = 3 to 4). (G, Left) Release and loading of dexamethasone over time, quantified by HPLC. Dexamethasone loading was determined by degrading backpacks postfabrication via chemical dissolution and quantifying dexamethasone content. Right, release and loading of IL-4 over time, quantified by ELISA. IL-4 loading calculated by cumulative release from backpacks after 14 d, at which point apparent drug release ceased. Mean ± SD (n = 3 to 4). For C, data were analyzed by two-tailed Student’s t test, ***P < 0.001. For E, data were analyzed by one-way ANOVA with Tukey’s HSD test; ns, not significant. For F, data were analyzed by two-way ANOVA with Sidak’s correction. ****P < 0.0001.