Biomedical Engineering Reference
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Fig. 12 Islet encapsulation within living HEK293 cells that express GFP. (a) Islets are enclosed
within a layer of HEK293 cells (that express GFP) by introducing surface modifications of
complementary ssDNAs. Islets modified with oligo(dT) 20 -PEG-lipid are combined with
HEK293 cells that have oligo(dA) 20 -PEG-lipid immobilized on the surface. DNA hybridization
immobilizes the HEK293 cells to the surface of the islets. After 3 days in culture, islets are
completely encapsulated within HEK293 cells. (b) Phase contrast ( left panels ) and fluorescence
images ( right panels ) of islets with attached HEK293 cells at 0 and 3 days after immobilization.
GFP-HEK293 cells immobilized to islets were observed with a confocal laser-scanning micro-
scope. Frozen sections of islets with attached GFP-HEK293 cells were stained with AlexaFluor
488-labeled anti-insulin antibody ( green ) (3-day samples). The 3-day samples were also stained
with Hoechst 33342 dye ( blue ) for nuclear staining
5 Summary
Understanding biological responses against foreign substances has led to the devel-
opment of various medical devices, artificial organs, and regenerative medicine
approaches. SAMs of alkanethiols formed on a thin gold layer coated on a glass
plate provide a platform for studying protein adsorption and cell adhesion to
artificial materials. Although many questions remain to be answered before we
fully understand the mechanisms of cell adhesion to artificial materials, rational
studies can be conducted with SAMs. SAMs were used for developing a culture
substrate for selective proliferation of NSCs. Based on the findings, we constructed
a NSC culture module to facilitate the large-scale production of high purity NSCs.
The ssDNA-PEG-lipid provides versatility in cell surface modifications. It
enables the immobilization of a broad spectrum of proteins and low molecular
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