Optimal size of cell-laden hydrogel cylindrical struts for enhancing the cellular activities and their application to hybrid scaffolds.

Biomedical scaffolds must be mechanically stable and highly porous three-dimensional (3D) structures to allow efficient cell-to-cell and cell-to-substrate interactions, induce blood vessel formation, and transfer oxygen, nutrients, and metabolic waste. A 3D cell-laden hybrid scaffold consisting of a combination of structural synthetic polymers and a cell-laden hydrogel is an outstanding biomedical scaffold due to its controllable mechanical properties, multiple cell loading, and homogeneous cell-distribution within the scaffold. But although this hybrid scaffold is better than conventional scaffolds, some issues must still be overcome. One is the controllability of cell release from the cell-embedded hydrogel. Here, we propose a method to solve this problem using a geometric cell-laden hydrogel. Various cylindrical cell-laden strut sizes (diameter: 100, 200, 400, and 800 μm) using osteoblast-like-cells (MG63) were investigated A diameter of 200 μm was the most attractive to efficiently induce cell release and proliferation based on cell viability and fluorescence analyses. In addition, cell-laden alginate struts (200 and 800 μm) were used to fabricate poly(ε-caprolactone) hybrid scaffolds; the hybrid scaffolds were interlayered with a cell-laden hydrogel (200 μm), demonstrating significantly high osteogenic expression compared to scaffolds laden with 800 μm struts.