Electrospun silk fibroin nanofibers promote Schwann cell adhesion, growth and proliferation

Abstract

In this study, Schwann cells, at a density of 1 × 10(5) cells/well, were cultured on regenerated silk fibroin nanofibers (305 ± 84 nm) prepared using the electrospinning method. Schwann cells cultured on the silk fibroin nanofibers appeared more ordered, their processes extended further, and they formed more extensive and complex interconnections. In addition, the silk fibroin nanofibers had no impact on the proliferation of Schwann cells or on the secretion of ciliary neurotrophic factor, brain-derived neurotrophic factor or nerve growth factor. These findings indicate that regenerated electrospun silk fibroin nanofibers can promote Schwann cell adhesion, growth and proliferation, and have excellent biocompatibility.

Keywords: Schwann cells; electrospinning; nerve tissue engineering; neural regeneration; peripheral nerve regeneration; silk fibroin.

Figure 1

Scanning electron micrograph of electrospun silk fibroin nanofibers (scale bar: 10 μm).

Figure 2

Schwann cells from the dorsal root ganglia cultured on polylysine and electrospun silk fibroin nanofibers (light microscopy, scale bars: 40 µm).

Figure 3

Immunocytochemistry of dorsal root ganglia cultured for 2 days (scale bars: 20 µm). Red: S-100 immunopositive cells, that might be considered Schwann cells; blue: nuclei labeled with Hoechst 33342.

Figure 4

Scanning electron micrographs of dorsal root ganglia-derived cells cultured on electrospun silk fibroin nanofibers after 2 days of culture (scale bar: 20 µm in A, 5 µm in B).

Figure 5

MTT assay for cell proliferation. At least three repeat tests were performed. Data were expressed as mean ± SD. One-way analysis of variance, followed by Student-Newman-Keuls test, was performed to analyze the difference between groups. The absorbance values for cells grown on silk fibroin and polylysine showed no significant difference during 1-5 days of culture (P > 0.05).

Figure 6

Quantification of NGF, CNTF, BDNF levels in culture mediums secreted by SCs after 4 days of culture using ELISA analysis. Data were expressed with mean ± SD. One-way analysis of variance followed by Student-Newman-Keuls test was performed to analyze the difference between groups. There was no significance of variance difference at NGF, CNTF and BDNF levels between silk fibroin and polylysine. NGF: Nerve growth factor; CNTF: ciliary neurotrophic factor; BDNF: brain-derived neurotrophic factor; SCs: Schwann cells.