Biointerfaces Between Cells and Substrates in Three Dimensions - Biointerfaces: Where Material Meets Biology - page 148

possible with several trypsin-EDTA incubations, interspersed with culture
media rests so as not to expose the cells to the protease for prolonged per-
iods. Extracted cells via this method appeared healthy and performed nor-
mal cell functions. They were also subsequently seeded onto new scaffolds
and continued to grow successfully in three dimensions, indicating the
potential for 3D passaging opportunities.

d n 3 r 4 n g | 3

TIP: For 3D cell extraction from Alvetex s using trypsin-EDTA solutions,
typically 3 5 min trypsin-EDTA incubations interspersed with 2 3min
culture media incubations is sucient to extract some cells from Alvetex s .

6.4 Future Direction of Biointerfaces in Three
Dimensions
Growing cells at the 3D interface is rapidly becoming standard practice for
many research laboratories. This new benchmark enables scientists to ap-
proximate the structural and physical aspects of the native environment that
were not possible with conventional 2D interfaces. Future work has now
focused on further developing and optimising these 3D models to include
additional aspects of the in vivo environment, such as specific biochemical
or mechanical components. For example, 3D co-culture is now receiving a lot
of attention as a means of improving the biochemical environment. Many
organs and tissues are composed of multiple cell types that provide various
biochemical stimuli for one another, such as secreted growth factors or
specific cell surface ligands or receptors. Mimicking this scenario in three
dimensions would therefore be advantageous, especially if the different cell
types could also undergo discrete structural organisations representative of
the native tissue. Another development area for 3D culture models is repli-
cating blood flow using perfusion or bioreactor systems. Not only does this
help to replicate some of the mechanical stresses introduced from blood
flow, it also helps to distribute media throughout the 3D cell mass, offering
opportunities to create nutrient gradients between cells. Hepatocytes, for
example, constantly experience blood flow coming from the digestive sys-
tem. Depending on where a particular hepatocyte is located in the 3D cord, it
will experience either a nutrient-rich or nutrient-poor blood supply. This
heterogeneity is actually very important for hepatocyte function, thus
mimicking this with 3D perfusion models could also enhance functional
behaviour in the laboratory. Finally, a significant proportion of research has
now turned to improving the surface chemistry of synthetic 3D substrates.
Consequently the field of synthetic polymer biomaterials is now thriving
with synthetic 3D materials that have been functionalised with peptides,
carbohydrates, proteins and other biomolecules.
In summary, 3D biointerfaces are now an integral part of cell biology and
biomedicine. A range of natural and synthetic materials can be used to
create such interfaces, with the choice of material depending heavily on the

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