Particle stabilised high internal phase emulsion scaffolds with interconnected porosity facilitate cell migration

A key challenge in bone tissue engineering (BTE) is designing structurally supportive scaffolds, mimicking the native bone matrix, yet also highly porous to allow nutrient diffusion, cell infiltration, and proliferation. This study investigated the effect of scaffold interconnectivity on human bone marrow stromal cell (BMSC) behaviour. Highly interconnected, porous scaffolds (polyHIPEs) were fabricated using the emulsion templating method from 2-ethylhexyl acrylate/isobornyl acrylate (IBOA) and stabilised with ~200 nm IBOA particles. Pore interconnectivity was tuned by varying the internal phase fraction from 75 to 85% and characterised by the degree of openness (DOO), Euler number, frequency and size of pore interconnects. The attachment, proliferation, infiltration, and osteogenic differentiation of the BMSC cell line (Y201) were evaluated on these scaffolds. Results showed that high pore interconnectivity facilitated diffusion and cell infiltration throughout the scaffolds. Furthermore, the most interconnected scaffolds enhanced osteogenic differentiation of Y201 cells, as evidenced by elevated alkaline phosphatase (ALP) activity and increased calcium and collagen production compared to less interconnected scaffolds. These findings emphasise the importance of scaffold interconnectivity in BTE for efficient nutrient transport, facilitating cell migration and infiltration, and supporting the development of interconnected cell networks that positively influence osteogenic differentiation.