An Approach for Fabricating Hierarchically Porous Cell-Laden Constructs Utilizing a Highly Porous Collagen-Bioink

In bioprinting procedures, bioinks typically comprise hydrogels, necessitating a balance between printability and bioactivity. Achieving good printability requires a relatively high hydrogel viscosity, but this can reduce bioactivity due to poor cell-to-cell interactions of the encapsulated cells. Therefore, developing hydrogels with excellent printability and bioactivity is a significant challenge in bioprinting. Here, a collagen-based bioink with excellent printability and bioactivity is developed. The bioink is prepared through a two-step process: first, by subjecting the bioink to whipping to create a non-homogeneous porous structure, and subsequently, by employing centrifugation to refine this porous structure into a uniform and relatively smaller microscale porous structure (with a specific diameter of 15.7 +/- 9.2 mu m). Using the designed bioink, a hierarchical porous structure is fabricated without any special equipment or supporting/sacrificing materials. To demonstrate the feasibility of the collagen bioink laden with human adipose stem cells, a hierarchical cell construct is fabricated using a bioprinter. The construct exhibits significantly enhanced cellular activities and superior osteogenic differentiation compared to the bioprinted cell constructs using normal collagen bioink. These findings suggest that collagen-based bioinks, which are both printable and bioactive, hold significant promise for extensive utilization in a variety of tissue regeneration applications. A collagen-based porous bioink, formed through a process of whipping and centrifugation, facilitates the fabrication of a cell-laden hierarchical porous structure for tissue engineering. This structure enhances various cellular activities of the laden adipose-derived stem cells, and the bioink, possessing both printability and bioactivity, shows considerable potential for various tissue engineering applications. image