In vitro evaluation of 3D printed polycaprolactone scaffolds with angle-ply architecture for annulus fibrosus tissue engineering.

T R Christiani,J Stanzione,E Baroncini,A J Vernengo

doi:10.1093/rb/rbz011

Abstract

Tissue engineering of the annulus fibrosus (AF) is currently being investigated as a treatment for intervertebral disc degeneration, a condition frequently associated with low back pain. The objective of this work was to use 3D printing to generate a novel scaffold for AF repair that mimics the structural and biomechanical properties of the native tissue. Multi-layer scaffolds were fabricated by depositing polycaprolactone struts in opposing angular orientations, replicating the angle-ply arrangement of the native AF tissue. Scaffolds were printed with varied strut diameter and spacing. The constructs were characterized morphologically and by static and dynamic mechanical analyses. Scaffold surfaces were etched with unidirectional grooves and the influence on bovine AF cell metabolic activity, alignment, morphology and protein expression was studied in vitro. Overall, the axial compressive and circumferential tensile properties of the scaffolds were found to be in a similar range to the native AF tissue. Confocal microscopy images indicated that cells were able to attach and spread on the smooth polycaprolactone scaffolds, but the surface texture induced cellular alignment and proliferation. Furthermore, immunofluorescence analysis demonstrated the aligned deposition of collagen type I, aggrecan and the AF-specific protein marker tenomodulin on the etched scaffolds. Overall, results demonstrated the potential for using the scaffolds as a template for AF regeneration.

Highlights

In the USA, reports have shown that low back pain (LBP) affects between 70 and 85% of the population at some point during their lifetime [1]
The morphology observed with scanning electron microscopy (SEM) (Fig. 2a–c) revealed a homogenous porous structure and the ability of the design to mimic the angle-ply architecture of the annulus fibrosus (AF)
Multi-layer scaffolds were 3D printed by depositing PCL struts in opposing angular orientations of 630, replicating the angle-ply arrangement of the native AF tissue

Summary

Introduction

In the USA, reports have shown that low back pain (LBP) affects between 70 and 85% of the population at some point during their lifetime [1]. LBP is frequently associated with degenerated and or injured intervertebral disc (IVD) [2]. Disc degeneration can result from damage to or dehydration of the NP, which reduces its hydrostatic pressure on the internal surface of the AF. This causes abnormal compressive stresses on the AF, causing tears, cracks and fissures after repeated loads. Disc degeneration may be treated pharmacologically, with physical therapy, or surgical intervention. These treatments do not address the underlying degenerative process, so recurrent symptoms and reoperation is common [6,7,8]

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