FIG. 4.

Focal images of a printed 3D SMC tissue construct and two-dimensional cell seeding distribution. (a) Illustration of 3D patch imaging. The distance between each imaged layer is 16.2 μm which is controlled by timed imaging and moving speed of a z-axis knob (Fig. 5). (b–e) Focal images of 3D patch layers; top layer of printed collagen in (b), second layer of SMC patch in (c), intermediate collagen layer in (d), and first layer of SMC patch in (e). (f) Cell distribution of two-dimensional patch of 1, 5, and 10 million cells/mL concentration after printing (day 0). Each patch size is 5 × 5 mm. Average number and standard deviation of printed cells for each patch were 26 ± 2 cells/mm² (average ± standard deviation) at 1 × 10⁶ cells/mL, 122 ± 20 cells/mm² at 5 × 10⁶ cells/mL, and 216 ± 38 cells/mm² at 10 × 10⁶ cells/mL. The number of cells is represented in log scale for comparison between 1 × 10⁶ and 10 × 10⁶ cells/mL. Scale bar: 100 μm. Color images available online at www.liebertonline.com/ten.