Bioprinting of cell-laden protein-based hydrogels: From cartilage to bone tissue engineering

The fabrication of cell-laden protein-based hydrogels (PBHs) for bioprinting necessitates careful consideration of numerous factors to ensure optimal structure and functionality. Bioprinting techniques, such as single-cell, multi-cell, and cell aggregate bioprinting, are employed to encapsulate cells within PBHs bioink, enabling the creation of scaffolds for cartilage and bone regeneration. During the fabrication process, it is imperative to account for biophysical and biochemical factors that influence cell behavior and protein structure within the PBHs. Precise control of crosslinking methods, hydrogel rheological properties, and printing parameters is also crucial to achieve desired scaffold properties without compromising cell viability and protein integrity. This review primarily focuses on the influence of biophysical factors, including composition, microstructure, biodegradation, and crosslinking, as well as biochemical factors, including chemical structure, growth factors, and signaling molecules, on protein structure and cell behavior. Additionally, key considerations for bioprinting PBHs and their impact on the successful regeneration of tissues are discussed. Furthermore, the review highlights current advancements, existing challenges, and promising prospects in the development of cell-laden PBHs for bioprinting applications and the regeneration of bone and cartilage.