Fabrication and evaluation of porous and conductive nanofibrous scaffolds for nerve tissue engineering

Yasaman Pooshidani,Zahra Hassannejad,Mina Rajabi,Masoumeh Haghbin Nazarpak,Nastaran Zoghi

doi:10.1007/s10856-021-06519-5

Abstract

Peripheral nerve repair is still one of the major clinical challenges which has received a great deal of attention. Nerve tissue engineering is a novel treatment approach that provides a permissive environment for neural cells to overcome the constraints of repair. Conductivity and interconnected porosity are two required characteristics for a scaffold to be effective in nerve regeneration. In this study, we aimed to fabricate a conductive scaffold with controlled porosity using polycaprolactone (PCL) and chitosan (Chit), FDA approved materials for the use in implantable medical devices. A novel method of using tetrakis (hydroxymethyl) phosphonium chloride (THPC) and formaldehyde was applied for in situ synthesis of gold nanoparticles (AuNPs) on the scaffolds. In order to achieve desirable porosity, different percentage of polyethylene oxide (PEO) was used as sacrificial fiber. Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM) results demonstrated the complete removing of PEO from the scaffolds after washing and construction of interconnected porosities, respectively. Elemental and electrical analysis revealed the successful synthesis of AuNPs with uniform distribution and small average diameter on the PCL/Chit scaffold. Contact angle measurements showed the effect of porosity on hydrophilic properties of the scaffolds, where the porosity of 75–80% remarkably improved surface hydrophilicity. Finally, the effect of conductive nanofibrous scaffold on Schwann cells morphology and vaibility was investigated using FE-SEM and MTT assay, respectively. The results showed that these conductive scaffolds had no cytotoxic effect and support the spindle-shaped morphology of cells with elongated process which are typical of Schwann cell cultures.

Highlights

Peripheral nerve injury causes long-term disabilities for patients and major socio-economic costs
The culture medium of DMEM/F12 supplemented with fetal bovine serum (FBS) (10%), The extent of sacrificial polyethylene oxide (PEO) fiber was tuned to 0, 20, 40, and 60% of the initial scaffold weight
To ensure that the designed combination of different syringes which were used for electrospinning resulted in the desired percentage of PEO within the PCL/Chit scaffolds, the actual percentages were verified through measuring the scaffolds weight before

Summary

Introduction

Peripheral nerve injury causes long-term disabilities for patients and major socio-economic costs. The common approach to repair a short-distance gap in peripheral nerve is direct suturing of two stumps. In cases of long nerve gaps, implantation of autologous nerve grafts such as sural nerve to bridge the gap is still the gold standard, but it suffers from limited length, lack of donor nerves, morbidity of donor site and scar tissue invasion. Nerve tissue engineering can be an alternative approach which provide a suitable and permissive microenvironment at the injury site using biocompatible scaffolds. An effective scaffold should provide required mechanical support for growing neurites, reduce scar tissue formation, and chemical (e.g., release of nerve growth factors) and physical (e.g., topographical and electrical) signals [1,2,3]

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