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Effect of gelatin source and photoinitiator type on chondrocyte redifferentiation in gelatin methacryloyl-based tissue-engineered cartilage constructs

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Abstract

Gelatin methacryloyl (GelMA) hydrogels are a mechanically and biochemically tuneable biomaterial, facilitating chondrocyte culture for tissue engineering applications. However, a lack of characterisation and standardisation of fabrication methodologies for GelMA restricts its utilisation in surgical interventions for articular cartilage repair. The purpose of this study was to determine the effects of gelatin source and photoinitiator type on the redifferentiation capacity of monolayer-expanded human articular chondrocytes encapsulated in GelMA/hyaluronic acid methacrylate (HAMA) hydrogels. Chondrocyte-laden hydrogels reinforced with multiphasic melt-electrowritten (MEW) medical grade polycaprolactone (mPCL) microfibre scaffolds were prepared using bovine (B) or porcine-derived (P) GelMA, and photocrosslinked with either lithium acylphosphinate (LAP) and visible light (405 nm) or Irgacure 2959 (IC) and UV light (365 nm). Bulk physical properties, cell viability and biochemical features of hydrogel constructs were measured at day 1 and day 28 of chondrogenic cell culture. The compressive moduli of all groups increased after 28 days of cell culture, with B-IC displaying similar compressive strength to that of native articular cartilage (∼1.5 MPa). Compressive moduli correlated with an increase in total glycosaminoglycan (GAG) content for each group. Gene expression analysis revealed upregulation of chondrogenic marker genes in IC-crosslinked groups, whilst dedifferentiation gene markers were upregulated in LAP-crosslinked groups. mPCL reinforcement correlated with increased accumulation of collagen I and II in B-IC, B-LAP and P-IC groups compared to non-reinforced hydrogels. A reduction in cell viability was noted in all samples at day 28, potentially due to the generation of free radicals during photocrosslinking or cytotoxicity of the photoinitiators. In summary, hydrogel constructs prepared with bovine-derived GelMA and photocrosslinked with Irgacure 2959 and 365 nm light displayed properties most similar to native articular cartilage after 28 days of cell culture. The differences in biological response between investigated construct types emphasises the necessity to characterise and standardise biomaterials before translating in vitro tissue engineering research to preclinical applications for articular cartilage injuries.

Graphical abstract: Effect of gelatin source and photoinitiator type on chondrocyte redifferentiation in gelatin methacryloyl-based tissue-engineered cartilage constructs

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Publication details

The article was received on 03 Oct 2018, accepted on 21 Dec 2018 and first published on 08 Jan 2019


Article type: Paper
DOI: 10.1039/C8TB02607F
Citation: J. Mater. Chem. B, 2019, Advance Article
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    Effect of gelatin source and photoinitiator type on chondrocyte redifferentiation in gelatin methacryloyl-based tissue-engineered cartilage constructs

    S. Pahoff, C. Meinert, O. Bas, L. Nguyen, T. J. Klein and D. W. Hutmacher, J. Mater. Chem. B, 2019, Advance Article , DOI: 10.1039/C8TB02607F

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