Mathematical Biology Seminar
Peter Vincent Imperial College London
Wednesday October 4, 2007
3:05pm in LCB 215 Sub-Cellular Scale Variations in
Low Density Lipoprotein Concentration
Adjacent to the Endothelium
Uptake of Low Density Lipoproteins (LDL) by the arterial wall is
likely
to play a key role in the process of atherosclerosis initiation. Not
only can such an uptake account for the lipid rich nature of
atherosclerotic lesions, it can also explain their patchy
distribution,
via mechanisms that spatially mediate the rate of trans-endothelial
LDL
transport.
A particular mechanism that may facilitate the non-uniform uptake of
LDL
is the formation of a flow-dependent LDL concentration polarisation on
the luminal side of the endothelium. In the study presented here the
effect of a spatially non-uniform transmural water flux (passing
through
intercellular clefts only) on such a concentration polarisation is
investigated computationally.
Results of the study show that under certain physiological conditions,
a non-uniform transmural flux will cause significant and
shear-dependent
sub-cellular scale variations in LDL concentration
polarisation. Further
results indicate that this can lead to a considerable shear-dependence
of LDL influx into the arterial wall, in addition to the
shear-dependence due to larger scale flow features affecting the
overall
degree of concentration polarisation. This additional effect (~23%
decrease in uptake as shear rate is increased from 0s^-1 to 3000s^-1 )
is seen when assuming transcytosis of LDL occurs only in regions
within
one micron of intercellular clefts. This is a reasonable assumption
since caveolae have been shown to occur most frequently near cell
edges.
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