Abstract
Cartilage defects and diseases remain major clinical issues in orthopaedics. Biomanufacturing is now a tangible option for the delivery of bioscaffolds capable of regenerating the deficient cartilage tissue. However, several limitations of in vitro and experimental animal models pose serious challenges to the translation of preclinical findings into clinical practice. Ex vivo models are of great value for translating in vitro tissue engineered approaches into clinically relevant conditions. Our aim is to obtain a viable human osteochondral (OC) model to test hydrogel-based materials for cartilage repair. Here we describe a detailed step-by-step framework for the generation of human OC plugs, their culture in a perfusion device and the processing procedures for histological and advanced microscopy imaging. Our ex vivo OC model fulfils the following requirements: the model is metabolically stable for a relevant culture period of 4 weeks in a perfusion bioreactor, the processing procedures allowed for the analysis of 3 different tissues or materials (cartilage, bone and hydrogel) without compromising their integrity. We determined a protocol and the settings for a non-linear microscopy technique on label free sections. Furthermore, we established a clearing protocol to perform light sheet-based observations on the cartilage layer without the need for tedious and destructive histological procedures. Finally, we showed that our OC system is a clinically relevant in terms of cartilage regeneration potential. In conclusion, this OC model represents a valuable preclinical ex vivo tool for studying cartilage therapies, such as hydrogel-based bioscaffolds, and we envision it will reduce the number of animals needed for in vivo testing.
Highlights
Cartilage defects and diseases remain major clinical issues in orthopaedics
Hydrogel-based biomaterials are commonly used with tissue engineering and 3D bioprinting techniques, and the typical cells used are adult chondrocytes and Mesenchymal Stromal/Stem Cells (MSCs) [11,12,13]
In recent work we have shown that the hydrogel formulation based on gelatin methacryloyl (GelMa) and hyaluronic acid methacrylate (HAMa), favors neocartilage formation in vitro in combination with adipose derived mesenchymal stem cells [35]
Summary
Cartilage defects and diseases remain major clinical issues in orthopaedics. Cartilage injuries cause pain and loss of function, and if severe may result in osteoarthritis [1,2]. A major challenge for cell-based products is to fulfil critical parameters to ensure a consistent quality of the product and thereby a consistent clinical effect [7,8]. These criteria should help evaluate the performance of emerging therapies, screen for factors that will optimize their efficacy, and predict the fate of these therapies. Such qualitative and quantitative assessment features include safety and efficacy of the cells used and the type of materials implanted to generate the bioscaffold [9]. Hydrogel-based biomaterials are commonly used with tissue engineering and 3D bioprinting techniques, and the typical cells used are adult chondrocytes and Mesenchymal Stromal/Stem Cells (MSCs) [11,12,13]
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