3D PRINTING AND NANOMANUFACTURING - 3D Bioprinting and Nanotechnology in Tissue Engineering and Regenerative Medicine - page 47

FIGURE 2.16
Fluorescence microscopy images of hMSCs seeded on (A, D) positive Poisson ratio (PPR) region and (B, C, E)
negative Poisson ratio (NPR) region. (C) Cells growing in scaffold voids and along scaffold struts in NPR region.
(D) Cells growing along scaffold struts (inset: SEM of scaffold struts) in PPR region. (E) Cells seeded on NPR region
(inset: SEM of scaffold struts). Scale bars represent (A, B) 250 μm and (C, D, E) 125 μm. Green: actin filaments;
blue: nuclei; pink: scaffold struts ( Soman et al. , 2012 ). A color version of this figure can be viewed online.
having 200 mW laser power and 830 nm wavelength. The specific cell patterning protocol was devel-
oped and described by Nahmias et al. ( Nahmias and Odde, 2006 ). HUVECs were guided in a mixture
of culture medium and Percoll solution (40%). Endothelial viability after patterning was 89% ± 7%.
The vascular structure of HUVEC (200 m m) was patterned using LGDW and self-assembly of cells.
Hepatocytes were then seeded on the fabricated structure to create a sinusoid-like structure, which is
one of the structural elements of the liver. The optimal seeding density was 50,000 cells per cm 2 for
both endothelial and hepatocytes to create robust formation.
Multiple laser beams were used to pattern fibroblasts on collagen-coated substrate with and with-
out myocyte culture ( Narasimhan et al. , 2004 ). Ti:sapphire laser beams had a wavelength of 780 nm.
Beam 1 and Beam 2 were perpendicularly aligned on an x - y plane that was vertical to the substrate
( z -direction). Beam 2 vertical ( x ) to z -direction had a higher laser intensity than beam 1 ( y ) parallel to
z -direction. This resulted in a slightly higher velocity for x -direction compared to that for y-direction.
The velocity was in the range of 45-150 m m/s.
Embryonic day 7 (E7) chick forebrain neurons were subjected to Ti:sapphire laser having 800 nm
wavelength ( Rosenbalm et al. , 2006 ). Two experiment parameter settings were compared to control
(cell culture without laser exposure): laser intensity of 300 mW at 60 s and one of 100 mW at 10 s.
The extension length of neurite was measured to analyze the influence of laser on neurons. There