EXTRACELLULAR MATRIX–BASED SCAFFOLDS FROM SCRATCH - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 390

replacement of, for example, urethra and blood vessels ( ∼ 6mm 26
and ≤ 6mm 27 in humans, respectively), whereas larger-diameter
tubes are required to repair defects in for instance the trachea
and esophagus (inner diameters of 1.2 cm 26 and 1.5-2 cm, 28
respectively).
Tubular porous scaffolds can be prepared by pouring the
collagen(-elastin) suspension in a tubular mold, followed by the
insertion of a cylindrical mandrel and subsequent freezing and
lyophilization. By adjusting the inner diameter of the mold and the
diameter of the mandrel, the wall thickness and inner diameter of
the tubular scaffold can be modified. Again, by adjusting the freez-
ing temperature, the pore sizecan be varied.
Figure 20.4 shows an example of a small-diameter collagen tube
(innerdiameter 3mm).
Figure 20.4. Macroscopic (A, B)andscanning electron microscopic (C,D)
images of porous collagen tubes with a 3 mm inner diameter prepared by
freezing and lyophilization. A) Macroscopic image of a dry collagen tube; B)
two collagen tubes sutured to each other under wetted conditions show-
ing its suturability. C) SEM image of the cross-section of a collagen tube
and D) SEM image of the lumen of the tube. Bars are in cm in A, B and are
1mminC,D.