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Research Projects
Inverted
Colloidal Crystals as Three Dimensional Microenvironments for
Cellular Co-Cultures
The unique
three-dimensional (3D) geometry of inverted colloidal crystal (ICC)
which is taking advantage of hexagonally close-packed (HCP)
colloidal crystal as a template provided ideal microenvironments
for the co-culture system with suspension and adherent cells.
Well interconnected open porous structure made it possible to
travel floating cells deep inside of the ICC scaffold, but
simultaneously the limited channel size and number of the
interconnected pores temporarily entrapped them. As a result,
some amounts of cells could be captured inside of the pore, and
they can extensively interact with matrix and feeder cells which
were already seeded and grew along the pore. From simplified
Brownian Dynamics simulations, it was observed that a floating
cell is in the vicinity of the scaffold surface or the adherent
cells coating the scaffold more than 40% of the time. This
well-defined and highly ordered microenvironment simulated bone
marrow and thymus niches for hematopoetic stem cells.
Inverted Colloidal Crystal 3-D Scaffolds for Liver Tissue Analog
for Toxicology Screening
Reliable in-vitro
liver tissue models for screening new drugs have long been
desired in pharmaceutical industry because liver toxicity
results in the failure of most human clinical tests. Compared to
conventional 2D flat culture, 3D multi-cellular spheroid
formation of liver hepatocytes significantly maintains cell
viability and functionality. However, it has been difficult to
control, standardize, and image 3D liver tissue culture models,
the important steps toward large scale high throughput screening
(HTS) and high content analysis (HCA). We present a new type of
3D liver tissue model constructed on inverted colloidal crystal
(ICC) scaffolds in a 96 well-plate. Spheroid size was controlled
with near perfect control of ICC scaffold pore diameter. In
addition, the highly transparent hydrogel matrix facilitates the
use of fluorescent confocal imaging. HepG2 human hepatoma formed
measurable spheroid after 3 days culture and maintained high
viability. Liver functions such as albumin secretion, urea
synthesis, and cytochrome P450 induction were confirmed in
spheroid culture and compared with 2D flat culture. The results
showed that 3D culture retained protein secretion capability,
but was less inductive for CYP450 presentation than 2D culture.
Ultimately our 3D culture system aims to be used as an ideal and
standardized format to construct in-vitro 3D liver tissue
model for various pharmaceutical assays.
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