Biomedical Engineering Reference
In-Depth Information
Of great significance are both the spatial chemical functionality and physical
morphology of the substrate surface. Cells appear to recognize the roughness of
a surface in terms of response which is very important, for example, as this
property pertains to implanted materials such as steel. This observation has led
to the orchestrated design of substrate morphology by photolithographic and
other techniques, for example, to produce pillars and wells which influence cell
adhesion and response. Another factor that has received relatively scant
attention is the rheological character, especially elasticity, of the substrate.
Experiments in recent years have shown that various cells are capable of
'sensing' the rigidly or elastic properties of the substrate. Both the effects of
surface morphology and elasticity on cellular properties are discussed later in
the text.
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2.3 The Eukaryotic Cell and Environment: A Pre´ cis
Animal eukaryotic cells have a dimension of the order of 50 nm and have
various organelles enclosed within a plasma membrane composed of a mixture
of amphipathic phospholipids and sterols. The membrane incorporates a wide
variety of proteins which have several functions including molecular transport
and biochemical signaling.
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An example of an internal organelle is the mito-
chondrion which is responsible for the production of adenosine triphosphate
(ATP).
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This type of cell also possesses an internal support structure called the
'cytoskeleton', which is composed of protein filaments. These moieties have
several functions that include cell motion and muscle contraction. It is
important to note that when it comes to the external environment of the cell,
the cytoskeleton also plays a crucial role, especially with respect to the property
of adherence.
Cells of whatever type are embedded in the ECM, which is composed of
fibrous proteins and a polysaccharide gel-like matrix (Figure 2.1). The ECM is
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Figure 2.1
Some components of the extracellular matrix.
