An ex vivo model using human osteoarthritic cartilage demonstrates the release of bioactive insulin-like growth factor-1 from a collagen-glycosaminoglycan scaffold.

J Wardale,N Rushton,L Mullen,S Ghose,D Howard

doi:10.1002/cbf.3112

J Wardale, N Rushton + Show 3 more

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https://doi.org/10.1002/cbf.3112

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Abstract

Biomimetic scaffolds hold great promise for therapeutic repair of cartilage, but although most scaffolds are tested with cells in vitro, there are very few ex vivo models (EVMs) where adult cartilage and scaffolds are co-cultured to optimize their interaction prior to in vivo studies. This study describes a simple, non-compressive method that is applicable to mammalian or human cartilage and provides a reasonable throughput of samples. Rings of full-depth articular cartilage slices were derived from human donors undergoing knee replacement for osteoarthritis and a 3 mm core of a collagen/glycosaminoglycan biomimetic scaffold (Tigenix, UK) inserted to create the EVM. Adult osteoarthritis chondrocytes were seeded into the scaffold and cultures maintained for up to 30 days. Ex vivo models were stable throughout experiments, and cells remained viable. Chondrocytes seeded into the EVM attached throughout the scaffold and in contact with the cartilage explants. Cell migration and deposition of extracellular matrix proteins in the scaffold was enhanced by growth factors particularly if the scaffold was preloaded with growth factors. This study demonstrates that the EVM represents a suitable model that has potential for testing a range of therapeutic parameters such as numbers/types of cell, growth factors or therapeutic drugs before progressing to costly pre-clinical trials. © 2015 The Authors. Cell Biochemistry and Function Published by John Wiley & Sons Ltd.SignificancePre-clinical trials of biomaterials for cartilage repair are very costly, and all too often, studies progress directly from in vitro studies using isolated cells to in vivo studies without investigating the interaction between the target tissue and the scaffold. Our study uses viable cartilage from adult human donors with osteoarthritis and therefore represents the exact scenario that the scaffold is designed for. The system is cheap and simple to set up and is suitable for a 48-well plate format, meaning a reasonable throughput is obtainable. This lends the model to therapeutic drug testing.

Highlights

Articular cartilage is a form of hyaline cartilage that covers the bony articulating ends of synovial joints
Histological staining demonstrated that the scaffold was in close contact with the cartilage in the model (Figure 1D) and that seeded cells populated the scaffold void (Figure 1E) and grew in close contact with the cartilage after 4 weeks in culture (Figure 1F)
Ex vivo models pre-treated with adsorbed insulin-like growth factor-1 (IGF-1) (AI) and those treated with IGF-1 plus TGF-β1 released a significantly higher amount of sulphated GAG into the media compared with the no-growth factors (GFs) control group after 28 days (Figure 2), but there were no significant differences between the GF groups

Summary

Introduction

Articular cartilage is a form of hyaline cartilage that covers the bony articulating ends of synovial joints. This stiff load-bearing tissue resists tensile forces, compression and shearing, while maintaining some resilience and elasticity. The unique biomechanical properties of articular cartilage are attributed to the complex zonal arrangement of its constituent macromolecules, collagen and proteoglycan, which are maintained by cells known as chondrocytes.[1] Injuries to articular cartilage yield poor intrinsic repair and present a major risk factor in the development of osteoarthritis (OA) in later life.[2] Partial. One active research area is the use of biomimetic scaffolds [either used alone or as vehicles to deliver growth factors (GFs)] to enhance the repair process.[7,8]

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