3D bioprinting of biomimetic self-assembling peptides and neural stem cells for nervous tissue engineering.

Abstract

Tissue engineering involves the creation of biological constructs using scaffolds, cells, and therapeutic factors. 3D bioprinting, using hydrogels as bioinks, allows precise deposition of cells and materials to develop 3D scaffolds with tunable shapes and porosity. Self-assembling peptide (SAP) hydrogels are gaining attention due to their nanofibrillar structure, biomimetic properties, biocompatibility, and ready tailoring for specific tissues. This study focuses on the development of 3D printed scaffolds using a SAP-based bioink, composed of a linear SAP and a blend of linear, branched, and functionalized SAPs, which promotes cell adhesion and differentiation, for nervous tissue engineering applications. A microfluidic RX1 bioprinter equipped with a coaxial printhead allowed precise control over cell deposition while minimising shear stress during printing. The printing process was optimised by testing different parameters and investigating rheological properties of the bioink, resulting in the successful printing of up to 10-mm-diameter ring-shaped and self-standing scaffolds. Scanning electron microscopy analyses revealed a highly porous nanofiber structure. Encapsulation of murine neural stem cells was achieved through two strategies: Strategy 1, in which SAP and cells were loaded separately, and Strategy 2, in which SAP and cells were mixed before printing. Although cell viability was slightly lower in the bioprinted constructs compared to the control, it increased over time with both strategies. Within 7 days, cells adhered well, sprouted, and differentiated into the main neural phenotypes (neurons, astrocytes, and oligodendrocytes). The present results confirm the potential of SAPs as bioinks for nervous tissue engineering applications.