. Dog-bone shape constructs with internal square openings of 1 mm side were printed using 3%GelMA-0.5%CBP-0.5%LAP and the conditions shown in Table . The samples were sterilized in a UV chamber and soaked in cell culture media for at least 4 h prior to cell seeding. Then, 2.5×10 5 hLFs were seeded on each construct and incubated (DMEM-10% FBS-1% A/A) at 37 ºC and 5% CO2 for 4 days. The cells were then starved overnight with FBS-free media (DMEM-1% A/A). Next, the samples were clamped in the CaT stretcher, and subjected to cyclic uniaxial stretching for 24 h at 20% strain and 0.2 Hz in DMEM-2% FBS-1% A/A. To model breathing without pauses, a single stretch cycle included a ramp up to desired level of strain over a duration of 2.5 s that was followed by a ramp down to baseline level of strain over a duration of 2.5 s. Thereafter, the samples were fixed and labeled for αSMA and F-actin quantification. Control samples incubated under static conditions were also analyzed.