High Throughput Techniques for the Investigation of Cell–Material Interactions - Biointerfaces: Where Material Meets Biology - page 265

and of those five, all were able to maintain the cells in an

undifferentiated state.

10.1.3 Screening of Cell-Surface Interactions: An Overview of
High-throughput Techniques
Screening of cell-surface interactions can be a time-consuming process
given the vast array of topographical, chemical and biological cues available
for investigation, which in turn translates into spiralling costs associated
with such experiments. Additionally, systematic errors associated with ana-
lysing individual samples can lead to uncertainties in results and hence a
requirement for increased numbers of replicates. The advent of high-
throughput screening techniques including protein and cell microarrays,
encoded microparticles, microfluidic devices as well as surface-bound gra-
dients has precipitated a paradigm shift in the field (Figure 10.3). 22,56,65,74-78
Pregibon et al. 78 have developed a high-throughput screening method
using encoded microparticles. Here, multi-functional particles displaying
encoding elements and analyte detection regions were developed using
microfluidics and continuous flow lithography (Figure 10.3A). In the ex-
ample shown, researchers loaded the particles with DNA oligomer probes
and incubated them with fluorescently labelled targets. Using flow-through
particle reading under a fluorescence microscope, different DNA oligomers
could be detected without the need for signal amplification. Kothapalli
et al. 77 investigated neuron-guided growth using microfluidic devices
(Figure 10.3). Here, hippocampal or dorsal root ganglion neuronal cells were
incubated inside a microfluidic device on a collagen gel. Upon induction of a
chemical gradient of various biomolecules known to influence neurite
growth including netrin-1, brain pump and slit-2, neurite turning was ob-
served to varying degrees depending on the applied cue and its
concentration.
The use of a microarray format, whereby many 'spots' of differing prop-
erties and chemistries can be immobilised onto a single substrate at a given

d n 3 r 4 n g | 7

.

(A) Substrate elasticity influences stem cell fate, 2 (i) range of stiffnesses
observed by solid tissues, (ii) images of MSCs grown on surfaces with a
range of stiffnesses for 4, 24 and 96 h, demonstrating the change in
morphology with substrate stiffness; (B) surface functional groups influ-
ence MSC phenotype, graph showing expression of various expression
markers: b-actin (increase in expression), ornithine decarboxylase (ODC,
indication of proliferation), collagen II (chondrocytes), CBFA1 (bone
transcription factor), collagen I (MSC marker), TGF-b3(ECMproduction)
on a variety of different functionalised surfaces; 62 (C) cell shape drives
hMSC commitment, (i) bright field images of MSCs grown on different
sized Fn islands (1024 mm 2 and 10 000 mm 2 ), (ii) % differentiation of
hMSC on different sized islands. 72
Figures A, B and C adapted from Engler et al., 2 Curran et al. 62

Figure 10.2

and

McBeath et al., 72 respectively.