Scaffold-Free Engineering of Human Cartilage Implants. (December 2021)

• Record Type: Journal Article
• Authors: Frerker, Nadine; Karlsen, Tommy A.; Lilledahl, Magnus Borstad; Brorson, Sverre-Henning; Tibballs, John E.; Brinchmann, Jan E.
• Is Part Of: Cartilage. Volume 13:Number 1(2022)Supplement
• Page Start: 1237S
• Page End: 1249S
• Publication Date: 2021-12
• Subjects: human articular chondrocytes -- chondrogenic redifferentiation -- human cartilage implants -- cartilage repair -- tissue engineering; Cartilage -- Periodicals; 616.7
• DOI: 10.1177/19476035211007923
• Languages: English
• ISSNs: 1947-6035

Abstract

Objective: Despite new strategies in tissue engineering, cartilage repair remains a major challenge. Our aim is to treat patients with focal lesions of articular cartilage with autologous hyaline cartilage implants using a scaffold-free approach. In this article, we describe experiments to optimize production of scaffold-free cartilage discs. Design: Articular chondrocytes were expanded in vitro, seeded in transwell inserts and redifferentiated using established chondrogenic components. Experimental variables included testing 2 different expansion media, adding bone morphogenetic protein 2 (BMP2), insulin-like growth factor 1 (IGF1), growth/differentiation factor 5 (GDF5), or fibroblast growth factor 18 (FGF18) to the differentiation medium and allowing the disc to float freely in large wells. Cartilage discs were analyzed by weight and thickness, real-time RT-qPCR (reverse transcriptase qualitative polymerase chain reaction), fluorescence immunostaining, transmission electron microscopy, second harmonic generation imaging, and measurement of Young's modulus. Results: Addition of BMP2 to the chondrogenic differentiation medium (CDM) was essential for stable disc formation, while IGF1, GDF5, and FGF18 were redundant. Allowing discs to float freely in CDM on a moving platform increased disc thickness compared with discs kept continuously in transwell inserts. Discs cultured for 6 weeks reached a thickness of almost 2 mm and Young's modulus of >200 kPa. There was abundant type II collagen. Collagen fibrils were 25 nm thick, with a tendency to be organized perpendicular to the disc surface. Conclusion: Scaffold-free engineering using BMP2 and providing free movement in CDM produced firm, elastic cartilage discs with abundant type II collagen. This approach may potentially be used in clinical trials.