Page 109 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

Figure 5.4 Three-dimensional electrospun heart valve sca olds made from a polyurethane:54 (a) view from the aortic side, (b) view from the ventricle side and (c) view of the complete valve.
fiber alignment, diameter and morphology, and bioactivity.
5.6.1 Sca old geometry
Electrospinning allows a direct fabrication of complex three-dimensional structures, such as heart valve sca olds. By selecting and manufacturing the appropriate shape and dimensions of the mold used for electrospinning, native valve geometries from various materials, such as PCL62,63 and PU, can be obtained (Figure 5.4).
5.6.2 Balancing sca old degradation and tissue formation
During the process of tissue engineering, the sca old provides for initial anchorage and support of the cells, until they have produced and organized their
own extracellular matrix to obtain a functional
tissue. A common hypothesis is: the rate of sca old degradation, and with it the loss of mechanical 5 strength, should be in pace with the rate of matrix
production. In addition, the engineered substitute
should meet and maintain identified mechanical
target properties upon implantation to resist in-vivo hemodynamic loading. Subsequent remodeling is
intended to recapitulate normal tissue architecture
and function. Thus, degradation properties and concomitant changes in mechanical properties need
to be incorporated into the sca old design.
So far mainly rapidly degrading synthetic sca olds, such as PGA, have been used for in-vitro tissue engineering. In such PGA sca olds, ECM formation and tissue mechanical properties can be stimulated within weeks depending on culture conditions.64
ELECTROSPINNING FOR HEART VALVE TISSUE REGENERATION
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