Science in Images: Fluorescent Staining of Mesenchymal Stem Cells

Mouse mesenchymal stem cells, incubated with polymer nanoparticles encapsulating the dye coumarin_6 (green) and the enzyme Cellulase (red).

Cells are incubated in chambers on a glass slide. During incubation endocytosis occurs: cells uptake the nanoparticles into them.

Cells have a mass of surface receptors, which can allow for very specific uptake. The uptake of nanoparticles by cells in this way can have huge implications for medical treatments, such directed chemotherapy.

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After the cells have been incubated for around 24 hours, they are fixed and stained with further dyes, so the cytoskeleton (purple) and the nucleus (blue) of the cell can be seen. The first image shows a low magnification of the cells.

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The next image is a Z-stack confocal image. In other words, multiple images of the cell were taken at different spacing in the Z-direction, to get slices throughout the cell. The Centre image shows the XY direction, or the cell parallel to the glass slide. The images below and beside this show the ZY and the ZX of the cell, or the perpendicular directions. What we can see using this technique is exactly where both the nanoparticles and the enzyme are within the cell.