Chitosan-Based Scaffolds and Hydrogels for Tissue Regeneration and Disease Modeling

Abstract

The extracellular matrix (ECM) is an essential supporting structure in tissue development. Conventional two-dimensional (2D) substrate could not faithfully represent the microenvironment of native tissue or cell construct. Recapitulating native ECM three-dimensional (3D) architecture and biochemical features has been found effective in eliciting more clinically relevant biomolecular responses. In modeling diseases, such as cancer and neurodegenerative disorders, the discrepancy among 2D versus 3D in disease modeling has resulted in decades of false interpretation of efficiency of therapies. Despite countless 3D matrices developed each year, very few of them could be consistently included in a standard protocol and widely available. Chitosan is a mammalian-cell-biocompatible polymer with a proxy structure of glycosaminoglycan, an important constituent of ECM. Chitosan is a versatile biopolymer that many have applied as ECM substrate mimics often in conjunction with other compounds. We fabricated chitosan-based hydrogels and macroporous scaffolds with varying microstructure and modified with ECM biomolecules. For tumor models, the 3D culture in chitosan-based hydrogels with varying mechanical properties led to multidrug resistance and higher malignancy from mammary carcinoma and human glioblastoma cells compared to controls. The hydrogels upregulated ATP-binding cassette transporters and dysregulated DNA mismatch repair pathway. For tissue regeneration and cell therapy, the polymer and surface composition of the scaffolds were tailored for human induced pluripotent stem cells (hiPSCs), human neural stem cells (hNSCs), or hiPSC-derived neurons. hiPSCs represent a powerful technology for tissue regeneration, cell therapy, and modeling human disease in vitro, but lack matrix-dependent 3D culture platform. The chitosan-based scaffolds demonstrated its support for hiPSCs, hNSCs, and the neurons. The hNSCs could be expanded during long-term maintenance on the scaffolds. Furthermore, hiPSC-derived neurons with mutations associated with early-onset familial Alzheimer’s disease have presented pathological features in 3D scaffold cultures. The 3D matrix likely led to better maturation and intercellular interactions that promoted neurite ourgrowth and synaptogenesis. Collectively, the Alzheimer’s disease and tumor modeling in our 3D scaffolds and hydrogels could help disease mechanistic understanding for the development of novel therapy. Additionally, the porous scaffolds present a cost-effective cell depot for pluripotent and multipoint cell cultivaton. The dispensable chitosan-based hydrogels provide an accessible material option for scaling 3D micro-tissue systems.