Low-temperature electrospun silk scaffold for in vitro mucosal modeling

Electrospinning is often used to create scaffolding as a biomimetic of the extracellular matrix of tissues. A frequent limitation of this technique for three-dimensional tissue modeling is poor cell infiltration throughout the void volume of scaffolds. Here, we generated low-temperature electrospun silk scaffolds and compared these with conventional electrospun silk scaffolds in terms of mechanical properties, void volume, cell infiltration, cell viability, and potential to support mucosal models under three-dimensional culture conditions. Low-temperature electrospun silk scaffolds supported fibroblast attachment and infiltration throughout the volume of the scaffolds, while conventional electrospun scaffolds exhibited limited cell infiltration with fibroblasts attaching exclusively to the seeding surface of the scaffolds. The porosity of low-temperature electrospun scaffolds was 93% compared with 88% of conventional electrospun silk scaffolds. Uniaxial tensile testing showed a 3.5-fold reduction in strength of low-temperature electrospun silk compared with the conventional in terms of peak stress and modulus but no significant change in strain at break. Mucosal modeling with fibroblast-keratinocyte or fibroblast-carcinoma cocultures showed similar results, with cell infiltration occurring only in low-temperature electrospun scaffolds. Cell viability was confirmed using live/dead staining after 21 days in culture. Furthermore, low-temperature electrospun silk scaffolds were able to support keratinocyte differentiation, as judged by involucrin immunoreactivity. The low-temperature electrospun silk scaffold that we have developed eliminates the limitation of electrospun silk scaffolds in terms of cell infiltration and, therefore, can potentially be used for a wide range of tissue engineering purposes ranging from in vitro tissue modeling to in vivo tissue regeneration purposes.