3D printing of methylcellulose-based hydrogels

Methylcellulose-based (MC) hydrogels are optimal substrates to obtain cell sheets for regenerative medicine applications. However, current MC-based hydrogel preparation methods only allow for the obtainment of MC substrates with standardized and simple geometries (i.e., geometry of the container where the hydrogel is produced). Here, we propose the 3D printing of a MC-based hydrogel to obtain substrates with desired and controlled geometries. First, we optimize the printing temperature (i.e., T = 21 °C) of the MC-based hydrogel, so to obtain printed strands reproducing the designed geometry without defects. We investigate the influence of the printing parameters (i.e., needle size, deposition speed and extrusion multiplier) on the printed strands diameters and printing accuracy. A decrease in the sol-gel transition temperature was evidenced, together with an increase in water uptake at 37 °C, for printed MC-based hydrogels compared to not printed samples; the stability at 37 °C and achieved rheological properties were suitable for cell sheet engineering applications. In addition, cell viability higher than 90% was detected after embedding cells in the MC-based hydrogel; moreover, the optimized printing parameters allowed to bioprint C2C12 cells embedded in the MC-based hydrogel with a viability higher than 80%. The printing parameters we optimized could be used to produce MC substrates for cell sheet engineering or cell delivery applications with controlled and complex-shaped geometries.