Astrocyte 3D Culture and Bioprinting using Peptide Functionalized Hyaluronan Hydrogels

Abstract

The often-forgotten astrocytes play an important role in the central nervous system, contributing to the development of and maintenance of synapses, recycling of neurotransmitters, and the pathophysiology of various neurodegenerative diseases. Hydrogels can provide improved support and attachment for the culture of astrocytes in 3D models, which could further be used to advance clinical in vivo like tissue models of numerous diseases. For full applicability, these gels must be of scalable and defined origin and with stable attachment elements, such as peptides. In this study, the generation of a functional 3D astrocyte model is presented using a hyaluronan-based hydrogel system conjugated with the peptide sequences cyclic RGD (cRGD) and IKVAV, known promoters of cell attachment. Encapsulation of the neuroblastoma cell line SH-SY5Y and glioblastoma cell line U87 is successfully demonstrated over a 6-day culture period. The presence of the peptides cRGD and IKVAV does not change the cells' viability. Human fetal primary astrocytes (FPA) are further tested for the 3D culture in these materials, similarly, showing that the peptides have no effect on the viability over a 6-day culture period. mRNA expression analysis reveals no biologically significant changes in the 3D cultures FPA or the U87 cells. Morphological analysis, on the other hand, revealed that FPA have a higher degree of interactions with the hyaluronan-based gels compared to the cell lines. This interaction is enhanced by peptide conjugation, in particular cRGD. Finally, we demonstrated that the peptide conjugated hydrogels could be used for bioprinting of FPA, opening up for defined neural astrocytic co-culture.