Maintenance of Ligament Homeostasis of Spheroid-Colonized Embroidered and Functionalized Scaffolds after 3D Stretch.

Clemens Gögele,Michael Meyer,Gundula Schulze-Tanzil,Bernd Hoffmann,Michaela Schröpfer,Jens Konrad,Rudolf Merkel,Annette Breier,Judith Hahn

doi:10.3390/ijms22158204

Abstract

Anterior cruciate ligament (ACL) ruptures are usually treated with autograft implantation to prevent knee instability. Tissue engineered ACL reconstruction is becoming promising to circumvent autograft limitations. The aim was to evaluate the influence of cyclic stretch on lapine (L) ACL fibroblasts on embroidered scaffolds with respect to adhesion, DNA and sulphated glycosaminoglycan (sGAG) contents, gene expression of ligament-associated extracellular matrix genes, such as type I collagen, decorin, tenascin C, tenomodulin, gap junctional connexin 43 and the transcription factor Mohawk. Control scaffolds and those functionalized by gas phase fluorination and cross-linked collagen foam were either pre-cultured with a suspension or with spheroids of LACL cells before being subjected to cyclic stretch (4%, 0.11 Hz, 3 days). Stretch increased significantly the scaffold area colonized with cells but impaired sGAGs and decorin gene expression (functionalized scaffolds seeded with cell suspension). Stretching increased tenascin C, connexin 43 and Mohawk but decreased decorin gene expression (control scaffolds seeded with cell suspension). Pre-cultivation of functionalized scaffolds with spheroids might be the more suitable method for maintaining ligamentogenesis in 3D scaffolds compared to using a cell suspension due to a significantly higher sGAG content in response to stretching and type I collagen gene expression in functionalized scaffolds.

Highlights

The anterior cruciate ligament (ACL) is an intraarticular ligament that stabilizes the knee joint and is one of the most frequently injured structures of the knee [1]
The aim was to evaluate the influence of cyclic stretch on lapine (L) Anterior cruciate ligament (ACL) fibroblasts on embroidered scaffolds with respect to adhesion, DNA and sulphated glycosaminoglycan contents, gene expression of ligament-associated extracellular matrix genes, such as type I collagen, decorin, tenascin C, tenomodulin, gap junctional connexin 43 and the transcription factor Mohawk
A functionalization of the scaffolds with 10% gas phase fluorination and a HMDI cross-linked collagen foam led to a superior outcome in regard to LACL cell colonization, sulphated glycosaminoglycan (sGAG) content, and their relative gene expression of type I collagen in comparison to the control scaffolds

Summary

Introduction

The anterior cruciate ligament (ACL) is an intraarticular ligament that stabilizes the knee joint and is one of the most frequently injured structures of the knee [1]. The current gold standard, using autologous tissues such as parts of the patellar ligament with its bony patellar and tibial attachments or the hamstring tendons does not always withstand the mechanical stress and leads to the so-called “donor site morbidity” [8] For this reason, the use of a suitable biomaterial-based transplant has been considered for a long time [9,10]. The tenogenic differentiation demonstrated by expression of the tendon-related transcription factor scleraxis and expression of ligament associated ECM components, such as types I and III collagens, tenascin C as well as fibronectin could be induced in human mesenchymal stem cells by cyclic stretching [30,31,32,33]. It was reported that in vivo ACL length and knee flexion are inversely related and that the native ACL can withstand a maximum elongation of 5% before rupturing [34,35]

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