Towards biofabrication of a viable modular auricular cartilage implant using a polymer fiber-reinforced hydrogel

Abstract

Event Abstract Back to Event Towards biofabrication of a viable modular auricular cartilage implant using a polymer fiber-reinforced hydrogel Iris Otto1, 2, Pedro Ferreira Da Costa1, 3, Corstiaan C. Breugem2, Moshe Kon2 and Jos Malda1, 4 1 University Medical Center Utrecht, Orthopaedics, Netherlands 2 University Medical Center Utrecht, Plastic, Reconstructive & Hand Surgery, Netherlands 3 University Medical Center Utrecht, Utrecht Biofabrication Facility, Netherlands 4 Faculty of Veterinary Sciences, Utrecht University, Equine Sciences, Netherlands Introduction: The past two decades have seen increased interest in the use of tissue engineering approaches towards the treatment of auricular deformations. These approaches utilize a combination of cells, bioactive cues, and supporting (bio)materials. Although neocartilage tissue production can be attained, engineering the human auricle keeps facing a number of challenges. These challenges include preserving cellular viability and the complex auricular shape after implantation under the tight skin envelope. Two factors play a role here: soft hydrogels in support of chondrocytes, and nutrient limitation in large non-vascularized constructs. The inferior mechanical properties of the resulting constructs lead to deformation and degradation, demonstrating the need for an adequate nutrient supply, as well as mechanical reinforcement. Biofabrication approaches have the potential to satisfy these requirements. Especially 3D-bioprinting has the ability to combine and deposit multiple materials into intricate architectures. In this study, we propose a novel approach to allow sufficient nutrient diffusion in large constructs by means of modular constructs. Furthermore, we created hybrid constructs for increased mechanical strength by combining gelatin methacrylate (gelMA) bioink with biodegradable polycaprolactone (PCL) fiber-reinforcement. Materials and Methods: Porcine articular and auricular chondrocytes were embedded in 10% gelMA hydrogels (6mm diameter) and cultured in vitro for 2 weeks before subcutaneous implantation in nude mice. Regenerative performance of these implants was evaluated after 6 and 12 weeks in vivo by means of histological and biochemical analysis. In addition, 3D-printed reinforcing PCL-fiber scaffolds were included within the cell-laden hydrogel constructs. This way, hybrid bio-constructs are generated in the shape of the human auricle, for which histological and biochemical evaluation is performed after in vitro maturation. Results and Discussion: In line with previous findings, articular chondrocytes adequately produced extracellular matrix [1],[2]. Nevertheless, auricular chondrocytes embedded within gelMA showed even more prominent neocartilage production as was visualized by proteoglycan and collagen stainings, and a significantly higher GAG/DNA ratio. Strong yet flexible modular PCL scaffolds could reproducibly be fabricated in the complex 3D shape of the auricle with the bioprinter. Hybrid constructs with considerable mechanical properties and with convincing structure and shape were successfully created. Conclusions: This study demonstrated that auricular chondrocytes in gelMA outperform articular chondrocytes. In addition, biofabrication of complex 3D modular auricular shapes was feasible, resulting in flexible yet strong scaffold for the reinforcement of cell-laden hydrogels. This combinatory approach holds promise for tissue engineering of auricular cartilage implants.