Ex vivo expansion of a hematopoietic stem cell on a murine stromal cell by 3D micro-pillar device.

Stromal cells alter their mode of attachment, cellular shape, and protein expression when placed on square arrays of micro-pillars. All the pillars we studied had 50 μm diameters, 85 μm pillar heights, were separated by 50 μm, and had an identical surface chemistry. We found that these micro-pillars provided many opportunities for mechanical interlocking and were more suitable attachment matrixes for cell adhesion and stretching of the overlying biomaterials. When the feeder layer cells of hematopoietic stem cells (HSCs) were cultured into the micro-pillar device, they could screen more hematopoietic cytokines, such as interleukin-3 (IL-3), and laminin into the medium. Consequently, the micro-pillar device provides a greater degree of HSCs expansion relative to the 25 T flask. The maximal expansion of the HSCs and the colony-forming unit (CFU) on the micro-pillar device increased 62.72-fold and 16.95-fold for 28 day culture, but there were only 58.08-fold and 6.8-fold expansion on the 25 T flask. The results showed a significantly higher expansion in the pillar device compared to the 25 T flask; moreover, the stemness was maintained. Therefore, the 3D micro-pillar device appears to be a more suitable culture substrate for HSCs expansion ex vivo.