Biomedical Engineering Reference
In-Depth Information
Figure 3
. Spatial distribution of one of the two competing species in a two-species competition
model with diffusion. Here the vertical axis indicates the relative amount of individuals of this
species against the two-dimensional space. Starting from a roughly uniform state, where both
species are equally distributed (except for a small noise), local exclusion takes place in some
areas. Those regions where the first is abundant match those where the second is depleted, and
vice versa.
These concepts have been applied to the study of cancer biology only recently
(18), and in the next section we explore some of the implications of applying
metapopulation dynamics models to the study of human cancer.
5.
METAPOPULATION DYNAMICS AND CANCER
HETEROGENEITY
The term
metapopulation
was coined by Richard Levins to describe a popu-
lation consisting of many local populations (19,20). Metapopulation models are
well adapted to describe systems composed of a set of patches of habitats. Visu-
alizing tumor tissue as an ensemble of populations, differing by the mutations
present in each group of cells makes the application of metapopulation dynamic
models to the study of cancerous tissues intuitively appealing.
The notion that invasive cancers are composed of diverse populations stems
from the sometimes striking variation in cell phenotype found in human tumors.
It is not unusual to observe nodules of unique appearance growing within larger
nodules of tumor groups of distinct morphology apparently coexisting next to
each other. Complementing these morphological observations, several groups of
