PCL scaffold with well-defined hierarchical pores effectively controls cell migration and alignment of human mesenchymal stem cells.

With an increasing incidence of orthopedic fractures due to the growing aging population, the demand for novel bone tissue engineering treatments is rising. Existing biopolymeric scaffolds have hierarchical structure, are biocompatible, and are biodegradable, but struggle to control pore size and interconnectivity, essential features to regulate cell alignment and mechanobiological signaling. This highlights the need to design a biopolymeric scaffold with well-defined hierarchical structure and optimized surface properties to improve bone regeneration. To accomplish this, we proposed a grid-in-grid manufacturing approach and fabricated a solvent-free 3D polycaprolactone (PCL) scaffold with hierarchical pores using precision extruding deposition (PED) 3D printing technology. The fabricated scaffolds exhibit both global pores and multi-scale local pores. Notably, using in vitro cultured human mesenchymal stem cells (hMSCs), controlled local pore size induced contact guidance and pore bridging, and the surface roughness of global strands effectively led to cell alignment. This study demonstrates that precision 3D printing technology can directly manipulate local pore structures to control cell migration and alignment. Furthermore, it could be applied for combined bone to connective tissue regeneration, where gradient pore structures and cell alignment are essential. Our scaffold has the potential to serve as a customizable platform for advanced tissue engineering applications.