Axonal extension from dorsal root ganglia on fibrillar and highly aligned poly(lactic acid)-polypyrrole substrates obtained by two different techniques: Electrospun nanofibres and extruded microfibres

Abstract

The biological behaviour of Schwann cells (SCs) and dorsal root ganglia (DRG) on fibrillar, highly aligned and electroconductive substrates obtained by two different techniques is studied. Mats formed by nanometer-sized fibres of poly(lactic acid) (PLA) are obtained by the electrospinning technique, while bundles formed by micrometer-sized extruded PLA fibres are obtained by grouping microfibres together. Both types of substrates are coated with the electrically conductive polymer polypyrrole (PPy) and their morphological, physical and electrical characterization is carried out. SCs on micrometer-sized substrates show a higher motility and cell-cell interaction, while a higher cell-material interaction with a lower cell motility is observed for nanometer-sized substrates. This higher motility and cell-cell interaction of SCs on the micrometer-sized substrates entails a higher axonal growth from DRG, since the migration of SCs from the DRG body is accelerated and, therefore, the SCs tapestry needed for the axonal growth is formed earlier on the substrate. A higher length and area of the axons is observed for these micrometer-sized substrates, as well as a higher level of axonal sprouting when compared with the nanometer-sized ones. These substrates offer the possibility of being electrically stimulated in different tissue engineering applications of the nervous system.

BDNF‐Gene Transfected Schwann Cell‐Assisted Axonal Extension and Sprouting on New PLA–PPy Microfiber Substrates

“…[ 50 ] The mass fraction of PPy (3.5 ± 0.7%) and the thickness of the PPy coating (122 ± 8 nm) were also quantified. [ 49 ] Regarding the electrical characterization, a conductivity of 1.36 ± 0.08 S cm −1 was obtained for the PLA–PPy substrates used in this study. [ 49 ] The distribution and the morphology of precultured SCs and DRG on PLA–PPy substrates were also studied.…”

“…[ 49 ] Regarding the electrical characterization, a conductivity of 1.36 ± 0.08 S cm −1 was obtained for the PLA–PPy substrates used in this study. [ 49 ] The distribution and the morphology of precultured SCs and DRG on PLA–PPy substrates were also studied. [ 49 ] Regarding the SCs, no significant effect of the PPy coating was observed on the distribution, motility, or morphology of these cells.…”

“…The physico‐chemical and electrical properties of the PLA–PPy substrates employed in this study have been extensively characterized in previous papers. [ 49,50 ] The presence of the PPy coating was confirmed by Fourier‐transform infrared spectroscopy (FTIR), observing the characteristic peaks of PLA, PPy, and pTS. [ 50 ] The mass fraction of PPy (3.5 ± 0.7%) and the thickness of the PPy coating (122 ± 8 nm) were also quantified.…”

“…The methodology followed for the quantification of axonal extension and axonal sprouting is explained in detail in ref. [ 49 ] . Below, it is explained briefly.…”

“…Herein, we sought to use PLA–PPy electroconductive highly aligned substrates based on microfibers since we have previously observed that they offer an enhanced axonal guidance and growth versus flat, nonaligned, or smaller fiber sized substrates. [ 49 ] In addition, the use of electroconductive substrates offers the possibility of its electrically stimulation in future experiments.…”