A SINGLE CELL PAIR MECHANICAL INTERROGATION PLATFORM TO STUDY CELL-CELL ADHESION MECHANICS
Cell-cell adhesion complexes are macromolecular adhesive organelles that integrate cells into tissues. Any perturbations of the cell-cell adhesion structure or related mechanotransduction pathways can lead to critical pathological conditions such as skin and heart diseases, arthritis, and cancer. The current techniques, however, have limitations on their ability to measure the cell-cell adhesion force directly and quantitatively.
In the current study, we designed and developed a single cell-cell adhesion interrogation and stimulation platform based on nanofabricated polymeric structures. The platform employs microstructures fabricated from biocompatible materials using an advanced nanofabrication technique, two-photon polymerization (TPP). The strain rate dependency of the junction has been investigated through the stretch test with four different strain rates. The results showed that the junction behaves in a strain-rate-dependent manner, where high strain rates lead to decreased viscosity property, a characteristic for a shear-thinning viscoelastic material. The maturation of this technology can pave the way for the in situ investigation of mechano-chemical signaling pathways mediated by cell-cell junctions and potentially reveal novel disease mechanisms in which defects in cell-cell adhesion play a significant role in the disease pathology.
icon search Searchable Transcript
Toggle between list and paragraph view.
[00:00:01.170]Hello everybody, I am Amir Monenian Esfahani from
Department of Mechanical and Materials
[00:00:06.000]Engineering. So, today
[00:00:08.100]I'm going to present a single pair
mechanical interrogation platform to a study
[00:00:12.000]cell-cell adhesion mechanics,
[00:00:14.580]so cells are tightly attached together to maintain the
cell, to maintain the tissue integrity.
[00:00:20.130]And they are always
objected to external forces.
[00:00:22.800]And these mechanical forces actually
motivate some activities with the
[00:00:27.570]cells like proliferation, migration and so on.
[00:00:31.570]So the cells should actually withstand
with these external forces and
[00:00:36.330]any mutations or auto-antibodies
to these cells can rupture cell-
[00:00:41.340]cell adhesion and make
some pathological effects on them.
[00:00:46.050]There are different strategies that cells
can actually dissipate the forces. At the
[00:00:50.970]cellular level, they have like
a catch bond formation, for example,
[00:00:54.750]these are like a two hooks together.
[00:00:56.640]And when you can apply the force between the cells,
[00:00:59.610]these ones are being stronger and
stronger. The other way is recruitment
[00:01:03.990]of vinculin or other proteins
to strengthen the cell-cell adhesion.
[00:01:08.910]The next one is clustering
[00:01:10.290]the number of bones at the
site that force is the maximum there
[00:01:15.510]at the tissue level, they
have cell oriented division.
[00:01:18.180]They have cell intercalation, and
they also have cell
So what's the problem.
[00:01:25.200]What's the statement
of the problem in here,
[00:01:27.870]how will these cells can adapt to
these external external forces
[00:01:32.310]whether they're mechanical or mechanotransduction pathway
[00:01:36.450]underneath that, the cells can sense these
forces and actually respond to them.
[00:01:41.370]So what are the crosstalks between the
focal adhesion and the cell-cell adhesion
[00:01:44.940]And so these are a few things that can
be studied through these contexts
[00:01:49.800]There are a few ways that
researchers have been focused on,
[00:01:55.140]for example, at the first one was a cell monolayer,
which is the easiest,
[00:01:59.520]they, they, as they grow the cells
in the monolayer type and then stretch
[00:02:04.050]them and study cell-cell adhesion and some
[00:02:07.080]they have cell-substrate adhesions.
[00:02:10.050]They have individual cells and they have,
[00:02:12.660]the single cell mechanical
[00:02:16.500]what all of them has their
own issues actually. For example,
[00:02:21.540]in the monolayers,
[00:02:22.800]cells have been shown that behaves
differently when they are in single
[00:02:27.750]cell and when they are in a
monolayer type or in the other one,
[00:02:31.830]when they have a study
to cell-cell adhesions,
[00:02:34.380]through cell-ECM or extracellular adhesion,
indirectly measuring these forces.
[00:02:40.380]And even for the single cell pair,
[00:02:42.190]they are not in like a
physiological environment. So they
[00:02:45.660]may behave differently.
[00:02:48.660]So here we defined and
designed and a new,
[00:02:51.390]actually, platform to study cell-cell adhesion.
As you can see in here,
[00:02:56.670]we have, uh, uh, two plates and a single
[00:03:00.160]cell pair are deposited on them.
[00:03:01.780]And then we stretch them and we're
capturing the deformation of these beams.
[00:03:05.860]We can find the stress and the strain curves through these
[00:03:10.300]platforms. So here is what we are doing.
[00:03:13.900]We are doing a structure modeling,
finite element analysis, fabrications,
[00:03:18.190]cell deposition, cell growth and proliferation,
[00:03:20.560]and then mechanical characterization.
[00:03:23.110]So we started with different generation of the platform,
[00:03:27.520]So, we started with the horizontal beams,
[00:03:29.590]only found that the stiffness of
these beams are not as similar to the
Then we moved to actually,
[00:03:38.830]uh, vertical beams then by some redesigning and
[00:03:43.570]these we should, we were able to design
and fabricate a very stable,
[00:03:48.670]uh, vertical platform to study the cell-cell adhesion
[00:03:53.290]as you can see at the top
was a bare substrate,
[00:03:56.080]nothing to confine the cells and in here when you deposit the cells,
[00:04:00.670]cells can move anywhere.
[00:04:02.920]So here we actually modified our
design to have a bow tie in the,
[00:04:08.090]on them to confine the cells
[00:04:10.390]And then we were able to
actually pick and place a cell
[00:04:16.090]on top of the structure
[00:04:20.710]and the same thing for the other
one. So we stained the cells,
[00:04:25.030]in a way that
we can actually see how
these cells proliferate
[00:04:29.470]and grow on the structure.
[00:04:30.840]And we saw that the polymer that we
were using was completely biocompatible
[00:04:35.740]and then we tried different
strain rates to stretch them.
[00:04:39.850]This is the lowest one. As you
can see, this cells are being,
[00:04:43.920]are being stretched and there
is no rupture occurs in there.
[00:04:48.850]And then the reason behind this is
that since the stretching is very slow,
[00:04:52.780]so the cells have enough time to adapt
themselves to the external forces
[00:04:57.640]by actually remolding, the cytoskeleton,
[00:05:00.880]or even by recruiting some other by recruiting
[00:05:05.020]some other proteins. The other
one, we actually increased
[00:05:10.320]the strain rate.
[00:05:12.820]And we saw that there are some like
a rupture and stiffening in here.
[00:05:17.290]And that's a really good phenomena.
[00:05:18.910]And we saw that there was a plateau
region in here that is actually balanced
[00:05:22.680]between the rupturing and actually
the stiffening of the whole
[00:05:27.160]structure. And the next one is
the highest one and the very fast,
[00:05:31.930]and you can see in here, just
cells are ruptured immediately.
[00:05:35.590]And this is because stress is accumulated
at the cell-cell junction.
[00:05:39.040]And then it makes it rupture.
We have some biomechanical
[00:05:43.840]model, modified standard linear model to
actually, interpret our cells
[00:05:48.940]behavior with different
strain rates. And as you can see,
[00:05:52.570]all the curves are matched
with our experimental data.
[00:05:55.720]And we saw that actually
the viscoelastic properties are being
[00:06:00.620]is decreasing by increasing
the strain rate.
[00:06:03.530]And also the cytoskeleton
growth is also decreasing by
[00:06:08.360]increasing actually the strain rates.
[00:06:12.590]So the conclusion, I want to
say in here, we actually were able to
[00:06:16.820]We were able to study the mechanical
properties of the cell cell adhesion
[00:06:20.990]directly in a physiologically relevant condition,
[00:06:24.500]which I studied
the strain rate
[00:06:26.630]dependency of the mechanical
[00:06:29.960]Thank you very much for
your attention. Bye.
Log in to post comments