A novel scale-down cell culture and imaging design for the mechanistic insight of cell colonization within porous substrate

At the core of translational challenges in Tissue Engineering is the mechanistic understanding of the underpinning biological processes and the complex relationships among components at different levels, which is a challenging task due to the limitations of current tissue culture and assessment methodologies. Therefore, we proposed a novel scale-down strategy to deconstruct complex bio-matrices into elementary building blocks, which were resembled by thin modular substrate and then evaluated separately in miniaturised bioreactors using various conventional microscopes. In order to investigate cell colonization within porous substrate in this proof-of-concept study, TEM specimen supporters (10-30µm thick) with fine controlled open pores (100~600µm) were selected as the modular porous substrate and suspended in 3D printed bioreactor systems. Non-invasive imaging of human dermal fibroblasts cultured on these free-standing substrate using optical microscopes illustrated the complicated dynamic processes used by both individual and coordinated cells to bridge and segment porous structures. Further in situ analysis via SEM and TEM provided high quality micrographs of cell-cell and cell-scaffold interactions at micro-scale, depicted cytoskeletal structures in stretched and relaxed areas at nano-scale. Thus this novel scaled-down design was able to improve our mechanistic understanding of tissue formation not only at single- and multiple-cell levels, but also at micro- and nano-scales, which could be difficult to obtain using other methods.