Influence of 3D printed porous architecture on mesenchymal stem cell enrichment and differentiation.

The interactions between cells and an underlying biomaterial are important for the promotion of cell adhesion, proliferation, and function. Mesenchymal stem cells (MSCs) have great clinical potential as they are an adult stem cell population capable of multilineage differentiation. The relationship between MSC behavior and several material properties including substrate stiffness and pore size are well investigated, but there has been little research on the influence of porous architecture in a three-dimensional scaffold with a well-controlled architecture. Here, we investigate the impact of two different three-dimensionally printed, pore geometries on the enrichment and differentiation of MSCs. 3D printed scaffolds with ordered cubic pore geometry were supportive of MSC enrichment from unprocessed bone marrow, resulting in cell surface marker expression that was comparable to typical adhesion to tissue culture polystyrene, the gold standard for MSC culture. Results also show that scaffolds fabricated with ordered cubic pores significantly increase the gene expression of MSCs undergoing adipogenesis and chondrogenesis, when compared to scaffolds with ordered cylindrical pores. However, at the protein expression level, these differences were modest. For MSCs undergoing osteogenesis, gene expression results suggest that cylindrical pores may initially increase early osteogenic marker expression, while protein level expression at later timepoints is increased for scaffolds with ordered cubic pores. Taken together, these results suggest that 3D printed scaffolds with ordered cubic pores could be a suitable culture system for single-step MSC enrichment and differentiation. STATEMENT OF SIGNIFICANCE: Mesenchymal stem cells (MSCs) have great therapeutic potential, as they are capable of multilineage differentiation. MSC behavior, including lineage commitment, may be influenced by biomaterial properties including substrate stiffness and pore size. With three-dimensional (3D) printing, we can investigate these relationships in 3D culture systems. Here, we fabricated scaffolds with two different well-controlled pore geometries, and investigated the impact on MSC enrichment and differentiation. Results show that scaffolds with ordered cubic pore geometry were supportive of both MSC enrichment from unprocessed bone marrow as well as MSC differentiation, resulting in increased gene expression during adipogenesis and chondrogenesis. These results suggest that 3D printed scaffolds with ordered cubic pores could be a suitable culture system for single-step MSC enrichment and differentiation.