Page 92 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

CHAPTER 4
in the handling process, there is still more void space available for the cell ingrowth compared to a conventional one. Also the fibers are, within limitations, freely movable so the cells might be able to move them out of their way.
There are many studies suggesting that it is beneficial to use sca olds, showing similar mechanical properties to the targeted tissue.29,44,45 In their physiological loading environment, most of the native tissues have a young’s modulus of lower than 1 MPa,30 e.g. muscle or arteries are around 100 kPa, so well in the range of the LTE spun sca olds. The process itself is also flexible enough to combine conventional and low-temperature spun layers. So a conventional layer, with thick fibers to still allow certain cell infiltration, could be included into sca old for more structural integrity when desired. Also spinning di erent fiber diameters and or materials is possible, e.g. in order to maximize the void space while spinning a so or a thin fiber.
4.4.5 Cell infiltration
To show the benefit of LTE spinning with respect to cell infiltration into an electrospun sca old, we performed a cell infiltration test by 7 days of culturing with seeded human vena saphena cells (HVSC). We selected the PCL sca old group with fiber diameters of 0.9 μm, since they provide the most challenging structures considering cell infiltration. Following the model of Eichhorn and Sampson9
these conventional electrospun sca olds o er the smallest SFD for cell infiltration from the sca olds we presented in this study. Furthermore, their LTE spun counterpart gained the least amount of void space in the LTE process as can be seen in Figure 4.6.
Hardly any cell infiltration was observed in the conventional spun sca old as shown by the cross sections in Figure 4.9. The cells, visualized as white spots, remained almost exclusively at the surface of the conventional spun sca old (Figure 4.9a). Testing cell infiltration on a sca old with the same fiber diameter, but LTE spun, demonstrates the large improvement that LTE spinning o ers. The HVSC are able to migrate into the sca old (Figure 4.9b). These results are in line with previous more extensive studies performed by other groups.24–27
Forces applied by the cells compacted both sca old types, though in a di erent way. The conventional electrospun strips got curled up along their length, which we attribute to the fact that most of the cells resided at the surface of the sca old. Compaction on the LTE spun sca olds resulted mainly in a change in thickness of 1.3 ±0.2 mm to 0.7 ±0.1 mm a er 7 days of culture. Overall, these results clearly show an enhanced cell infiltration potential in LTE spun sca olds versus conventional spun sca olds.
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