Biomedical Engineering Reference
In-Depth Information
Fig. 7
A schematic of the smooth muscle cell organization in the medial layer of elastic arteries
as proposed by Rhodin (
1980
) . Each layer (
a-c
shows an end on view of the vessel) is arranged in
a spiral pattern (
top
) that if unrolled would show the cells organized in parallel strips (
bottom
). By
layering the sheets and rolling into a cylinder, the herringbone pattern of vascular smooth muscle
cells in the vessel can be recreated (
d
)
Since the medial layer has a distinct three-dimensional architecture that changes
from cell layer to cell layer, a different method of building up the multilayer tissue
needs to be used from that described previously. Each cell layer has its own arrange-
ment in relation to the others. Within each layer, however, the cells are organized in
parallel rows so that they are all running in the same direction (Fig.
7
). This is a
common organizational motif that has been studied using microfabricated channels
in substrates for cell monolayers. In order to build up the three-dimensional archi-
tecture that could lead to an engineered, small-diameter blood vessel with proper
strength and functionality, these individual layers can be stacked on top of
each other to build a medial layer with the proper number of layers and helical
pitch between layers. The ability to control the number of layers as well as the pitch
between layers is important because it is known that the pitch and thickness can
change between vessels found in different tissues.
To control smooth muscle cell (SMC) organization PDMS scaffolds were cre-
ated with parallel running channels. Channel widths of 20, 50 and 80 m m were
investigated to determine an optimal width. The depth of the grooves was kept at
5 mm. This depth is shallow enough to infl uence a monolayer of cells. The effects of
such a pattern on the organization of SMCs and their subcellular components, such
as F-actin fi laments, had never been investigated.
