Unidirectional neuronal cell growth and differentiation on aligned polyhydroxyalkanoate blend microfibres with varying diameters.

Lorena R Lizarraga‐Valderrama,Caroline S Taylor,Ipsita Roy,Frederik Claeyssens,Jonathan C Knowles,John W Haycock

doi:10.1002/term.2911

Abstract

Polyhydroxyalkanoates (PHAs) are a family of prokaryotic‐derived biodegradable and biocompatible natural polymers known to exhibit neuroregenerative properties. In this work, poly(3‐hydroxybutyrate), P(3HB), and poly(3‐hydroxyoctanoate), P(3HO), have been combined to form blend fibres for directional guidance of neuronal cell growth and differentiation. A 25:75 P(3HO)/P(3HB) blend (PHA blend) was used for the manufacturing of electrospun fibres as resorbable scaffolds to be used as internal guidance lumen structures in nerve conduits. The biocompatibility of these fibres was studied using neuronal and Schwann cells. Highly aligned and uniform fibres with varying diameters were fabricated by controlling electrospinning parameters. The resulting fibre diameters were 2.4 ± 0.3, 3.7 ± 0.3, and 13.5 ± 2.3 μm for small, medium, and large diameter fibres, respectively. The cell response to these electrospun fibres was investigated with respect to growth and differentiation. Cell migration observed on the electrospun fibres showed topographical guidance in accordance with the direction of the fibres. The correlation between fibre diameter and neuronal growth under two conditions, individually and in coculture with Schwann cells, was evaluated. Results obtained from both assays revealed that all PHA blend fibre groups were able to support growth and guide aligned distribution of neuronal cells, and there was a direct correlation between the fibre diameter and neuronal growth and differentiation. This work has led to the development of a family of unique biodegradable and highly biocompatible 3D substrates capable of guiding and facilitating the growth, proliferation, and differentiation of neuronal cells as internal structures within nerve conduits.

Highlights

Engineered scaffolds are designed to closely mimic the topography, spatial distribution, and chemical cues corresponding to the native extracellular matrix (ECM) of the intended tissue in order to support cell growth and differentiation
The number of neuronal cells increased significantly on medium fibres, large fibres, and PHA blend films when cocultured with Schwann cells. These findings suggest that Schwann cells are able to enhance neuronal cell growth significantly
Thereafter, the relationship between PHA blend microfibre diameter and neuronal growth under two conditions, individually and in coculture with RN22 Schwann cells, was evaluated. Results displayed from both single cell type and coculture studies revealed that all PHA blend fibre groups were able to support growth and to guide aligned distribution of neuronal cells when grown individually and in the presence of RN22 Schwann cells

Summary

Introduction

Engineered scaffolds are designed to closely mimic the topography, spatial distribution, and chemical cues corresponding to the native extracellular matrix (ECM) of the intended tissue in order to support cell growth and differentiation. In tissue engineering, both three‐ dimensional (3D) and two‐dimensional (2D) cell cultures are used. Porous scaffolds facilitate mass transfer and exchange of nutrients, metabolites, and gases. Their high surface area enhances cell adhesion and their interconnected porosity enables 3D cell ingrowth, which can be spatially controlled. Three‐dimensional culture techniques would allow a better understanding of neuron–glial cell communication but could contribute towards the development of scaffolds for peripheral nerve regeneration (Daud, Pawar, Claeyssens, Ryan, & Haycock, 2012)

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