Using melt-electrowritten microfibres for tailoring scaffold mechanics of 3D bioprinted chondrocyte-laden constructs

Abstract Moulded hydrogels reinforced with melt-electrowritten (MEW) microfibres to tailor mechanical properties show promise in the articular cartilage regeneration field. We aim to transfer this knowledge to bioprinted constructs of volumetric dimensions towards real anatomical shapes, using a previously established alginate methylcellulose (algMC) blend. We show the potential of algMC to be a bioink for MEW fibre-reinforced 3D printed constructs that have tailorable mechanical properties and support long-term culture of bioprinted human chondrocytes. It is hoped that these composite algMC-PCL scaffolds have potential for use in auricular (ear) cartilage regeneration as an alternative to current reconstructive treatments using autografted rib cartilage or high-density polyethylene implants. Scaffolds of different designs were assessed to determine the effect of the hybrid structure on compressive strength, as well as an initial in vitro experiment with human chondrocytes to assess cell viability, DNA, sGAG, and collagen II content. The inclusion of MEW PCL scaffolds showed up to a 7.5-fold increase in the maximum compressive stress after 7 days of incubation in DMEM compared to algMC only scaffolds. In vitro work showed there was no significant differences in the cell viability between groups after 21 days of culture. However, DNA and sGAG content (relative to cell number) showed an increase in algMC scaffolds reinforced with MEW PCL sheets with 750 μm pores suggesting a more favourable stiffness for chondrocyte extracellular matrix (ECM) deposition. Future work will investigate how the scaffold stiffness changes over time as materials degrade and ECM is deposited as well as further in depth analysis of the biological performance with relevance to auricular cartilage. This microfibre reinforced algMC scaffold provides a promising way to tailor the mechanical properties of bioprinted structures for chondrocyte delivery at clinically relevant dimensions.