Polysaccharide-based bio-ink for 3D printing of scaffolds for cartilage reconstruction

Hydrogels are widely used as bio-inks in 3D printing methods aimed at reconstructing the extracellular matrix of relatively soft tissues. The ability to control the printing process based on computer-aided design (CAD) of a patient's injured or missing body part promises to create patient-specific structures. [1] The physicochemical and biological properties of the formed hydrogel should be paralleled by a proper viscoelastic behavior of the formulation during and after extrusion from the printing nozzle. Physically crosslinked hydrogels are often preferred over chemically crosslinked systems because they do not require initiators or catalysts that induce cytotoxicity and require rigorous purification. Due to their structural composition and self-assembly behavior in aqueous media, some polysaccharides have an inherent ability to form strong networks under mild conditions. k-carrageenan (kC) is one of the most prominent examples [2]. kC is a sulfated polygalactan from red algae with a sulfate content of 25–30% and an average molecular weight well above 100 kDa that has a similar structure to glycosaminoglycans (GAGs), which are central components of connective tissue. For this reason, kC can be considered as a suitable scaffold material for tissue engineering. kC is water soluble at temperatures above 60 °C and hardens into a stable hydrogel when cooled. The kC network is characterized by a strong, fragile, multilayer morphology. kC blends with other tougher polymers such as polyvinyl alcohol (PVA) can improve mechanical properties and create porosity [3]. In our study, we investigate the suitability of an aqueous kC/PVA systems with three different weight ratios between the two polymers for the 3D printing of scaffolds for cartilage reconstruction. Their rheological behavior was investigated for effects on processing and product properties. In addition, we investigated the morphological features and mechanical properties, through quasi-static compression tests and dynamic mechanical analysis (DMA). The actual printability of the formulation was also tested with and without adipose-derived stem cell (SASC) spheroids. The cells were cultured for 21 days in the presence of two different media, resulting in an increased cell viability for all formulations when cells were cultured in chondrocytic differentiation conditions. References [1] Y. Zhang, L. Ye, M. Cui, B. Yang, J. Li, H. Sun, F. Yao, RSC Adv., 2015, 5(95), 78180-78191. [2] J.T. Oliveira, R.L. Reis, J. Tissue Eng. Regen. Med. 2011, 5, 421-36. [3] J. Necas, L. Bartosikova, Veterinarni Medicina, 2013, 58, 187–205.