Stem Cell Imaging: Tools to Improve Cell Delivery and Viability

Figure 2

Labeling approaches used in SCT. (a) Direct labeling combines ((a)-(i)) cells and contrast agent and may use a transfection agent to increase the amount of agent that crosses the cell membrane. ((a)-(ii)) The labeled cells are selected from primary cells and are then injected into the target area. ((a)-(iii)) Because the label diffuses as the cells divide, contrast signal will decrease as time passed. (b) In indirect labeling, ((b)-(i)) the cells’ genome is modified by reporter gene that encodes for receptors, fluorescent proteins, or enzymes. Except for fluorescent reporter protein, the reporter gene usually does not generate contrast signal itself, but is responsible for the activation of a contrast agent that is added at the time of imaging. ((b)-(ii)) Unlike direct labeling, constitutively expressing genes gene will be copied to daughter cells and the expanded cells can be imaged as well. Reproduced courtesy of Nature Publishing Group [7].

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