Biology Reference
In-Depth Information
CHAPTER
27
Modelling Using Living Cells:
Tissue Engineering and Synthetic
Morphology
Computers and physical analogues provide one way in which an investigator can
explore a model of a morphogenetic system that has been divested of extraneous complex-
ities and irrelevant activities. Such models have the advantages of convenience and of
'perfect knowledge': everything about them is designed and built by a human, so every-
thing about them is known unless an error has been made in their construction. They
have the disadvantage, though, that subjective judgements and assumptions have to be
used in summarizing morphogenetic mechanisms. More critically, they assume that other
aspects of living cells, such as noise, can be neglected or have been adequately captured
in the model. Because evolved life has not been designed by humans, we do not have the
'perfect knowledge' to be able to make these judgements reliably.
An alternative approach is to model using living cells, but to remove these cells from the
environment of an embryo, in which many things take place at once, and to 'run' a morpho-
genetic mechanism in a much simpler, controlled environment. The cells can either be normal
cells in a controlled environment (an approach that comes under the heading of 'tissue en-
gineering') or be cells carrying genes encoding engineered morphogenetic modules created
specifically to test a hypothesis (an approach that belongs to the new field of synthetic
biology). Living models have the advantage of more realism
d
the mechanism is operating
in a real living cell
d
and the advantage that the mechanism itself is being studied, not an
abstraction of it. They have the disadvantage of inconvenience and very incomplete knowl-
edge of the values (concentrations, mechanical stresses, phosphorylation states
) of the
system as it runs. The advantages and disadvantages of the two main strategies for model-
ling, in computers and in culture, are therefore complementary; they are maximally powerful
if they are used together.
There have so far been rather few examples of modelling done using living cells so
this chapter is necessarily brief. The approach has been included because it is likely to
become much more common in the near future, particularly as technologies for tissue
engineering and for synthetic biology become more powerful and more accessible to basic
researchers.
.
