Fig. 1.

Lymphatic drainage-on-chip recapitulates lymphatic structure, drainage, and dysfunction. (A) A schematic of the lymphatic drainage-on-chip platform. (B) Apical podoplanin (PDPN) expression on the luminal side of the vessel. (C) Lymphatic sprouting in response to VEGFC stimulation. (D) Immunostaining of LEC-generated lymphatic vessels and BEC-generated blood vessels with a tight junction marker, JAM-A. (E) Immunostaining of lymphatic vessels and blood vessels with an adherens junction marker, VE-cadherin (VE-cad), and CD31. Red and yellow arrows indicate exclusive expression of VE-cad and CD31, respectively, showing interdigitated, discontinuous expression of VE-cad in LECs. (F) A schematic of a biomimetic lymphatic drainage-on-chip model system. The engineered lymphatic vessel (LV) in the right-side channel functions as an initial LV to drain interstitial lymph fluid that is introduced through the left-side channel. (G) Transport of lymph fluid. The left-side channel pressured with lymph fluid induces fluid transport. The pressure gradient between two channels results in fluid convection from the left channel to the engineered LV. The lymph fluid is drained by the engineered LV and accumulated in two right-side reservoirs. Total drained fluid is analyzed to obtain the number of drained lymph molecules. (H) Percent drainage of lymph molecules through LEC and BEC-line channels as compared to acellular channels (No cell), (N = 4). (I) Representative images of BODIPY-C₁₆ fatty acid drainage by LEC-generated lymphatic vessels and BEC-generated blood vessels. (J) Percent lymphatic drainage after cytokine exposure (BODIPY-C₁₆ fatty acid drainage), (N = 5). (K) VE-cadherin staining of engineered lymphatics after cytokine exposure. (L) Percent zipper junction in engineered lymphatics after cytokine exposure, (n = 8, N = 3 experiments). [Scale bars (A–E and I), 100 μm; Scale bars (K), 50 μm.] *P < 0.05 and **P < 0.01 indicate statistical significance.