Figure 3.

Creation of a 1:1 scale rat liver-shaped modular assembly using a PDMS bioreactor. (i) A rat liver was fixed in buffered formalin overnight and then air dried overnight. (ii) The liver was sheathed in plastic wrap which served as a barrier against PDMS infiltration. Female Luer threads were inserted into the top and bottom of the liver to serve as the inlet and outlet ports of the bioreactor. 20 gauge needles were threaded through the Luer threads to anchor them to the liver. (iii) The liver was immersed in PDMS, which was degassed to remove any air bubbles and cured. (iv) After curing, the needles were removed, a window was cut into the cast and the sheathed liver was removed, leaving the embedded Luer threads (inlet and outlet ports) behind. (v) The window was re-sealed with additional PDMS, cured and sterilized through steam autoclaving. The internal volume of the liver-shaped void space was 5 mL. (vi) The bioreactor was filled with modules (3.5 mL) and connected to a closed loop flow circuit. With a peristaltic pump, medium was drawn from a reservoir, through a flow dampener to remove air bubbles and eliminate backflow, and pumped into the bottom inlet of the bioreactor. Perfusing the reactor from the bottom ensured the entire volume was filled with medium (i.e. limited channeling). The out flow was returned to the reservoir. (b) A completed bioreactor filled with modules. (i) A 1:1 scale adult rat liver-shaped bioreactor with a total internal volume of 5 mL was filled with modules containing embedded luciferase-expressing L929 cells. The bioreactor was perfused for 3 days at a flow rate of 0.4 mL/min. Scale bar = 1 cm. (ii) Luminescence of L929 modular construct after 3 days of perfusion. Luciferin was perfused through the modular construct and the embedded L929 cells displayed luminescence, illustrating their viability. Size scale bar = 1 cm and colour bar is in the units of photon flux (photons/s/cm²/sr).