Biomedical Engineering Reference
In-Depth Information
the individual: this is due to the elongation process (captured also in Figure
10.6) caused by the confined geometry of the channel.
Instead, in the smallest channel, cells display a stepwise push-and-pull be-
havior, characterized by oscillating variations of cell length; see Figure 10.6
(bottom panel), which has been also observed in [332]. This migratory phe-
nomenology has a possible interesting mechanical explanation. The geometry
of the channel causes the cytosolic front of the cell to protrude. Pushed by the
leading front, the overall cytosolic region, characterized by high elasticity and
mobility, then deforms and moves forward, while pulling onto the nucleus with
the force exerted through the contact tension J
int
N;C
. However, as a consequence
of its lower elasticity and motility (i.e., T
;N
< T
;C
and
surface
;N
>
surface
;C
),
the nuclear cluster takes more time to remodel toward a very elongated mor-
phology and to displace, and therefore lags behind (as reproduced in Figure
10.4 and explained in more detail for the chemotactic migration of an endothe-
lial cell in Chapter 6), limiting the elongation of the overall cell (which has
to maintain its volume). Indeed, the displacement of the trailing part of the
cytosol decreases the length of the individual. However, when such a rear part
has moved far enough to the right, the nucleus, in order to avoid the split of
the cell, is forced to move. Therefore, it pushes the leading part of the cell,
which can go on elongating, increasing again the overall cell length.
It is noteworthy that this dramatic and continuous reorganization of the
nuclear cluster is not necessary for cell movement in the middle and large
channels. Indeed, in those cases, the nucleus undergoes only slightly defor-
mations and is therefore more easily dragged by the rest of the cell, whose
whole locomotion is eventually characterized by the above-described sliding
dynamics.
The push-and-pull pattern is similar to the classical migration of fibroblasts
on flats surfaces [229], and is consistent with the results obtained again in [332]
for pancreatic cancer cells moving in microchannel structures.
Search WWH ::
Custom Search