Page 31 - Tailoring Electrospinning Techniques for Regenerative Medicine - Marc Simonet

With the increase in control of the electrospinning process gained in recent years, two new methods to produce 3D sca olds are standing out. One method relies on the controlled deposition of fibers, the other on controlling the structural self-assembly. Controlling the fiber deposition allows for designs very similar to 3D printing, hence one can build up a sca old with defined voids for cell ingrowth. For melt electrospinning of PCL this method is already very promising, while solution electrospinning still needs some refinement to transfer it from 2D into 3D sca olds.105,129,130 The second method enables the creation of large voids by controlling charge dissipation or its build up, for example to create 3D honeycomb structures.131
To guide cell in-growth or further add bioactivity or to tailor and influence the sca old bio- as well as general- functionality, additives can be incorporated, such as growth factors, minerals, nanoparticles or contrast agents.132–136 These additives can be directly incorporated into the spinning solution prior to spinning, or in a second process step, the latter for example if the additives are sensitive to the electrospinning solution or voltage.137
1.7 Challenges of electrospun 1 sca olds for tissue engineering
with thesis outline
The challenges in electrospinning for tissue engineering are manifold. This is partially reflected by the very few electrospun biomedical products on the market. One of the main reasons for this is the hardly reported, but well known, lack of reproducibility. This, above all, held back the development of medical products. In addition, the inadequate mechanical sca old strength and limited cell infiltration and nutrition exchange are among the key reported remaining challenges of the electrospinning technique. Finally, a growing concern is the toxicity of the used solvents and their residues in the produced sca olds.
In the present thesis we aim to find methods to resolve the most critical of theses mentioned challenges and develop and apply electrospun sca olds for in-situ heart valve tissue engineering.
To investigate and improve the reproducibility issues, we used a prototype climate controlled electrospinning chamber. In chapter 2 we investigate the e ects of relative humidity and temperature on the electrospinning process and show how some of the resulting sca old characteristics can be directly influenced by changing these environmental conditions.
GENERAL INTRODUCTION
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