Figure 4.

Hypoxic preconditioning promotes cell retention in vivo. (A): In order to establish a correlation between cell number and luminescence intensity (exerted by luciferase-expressing mesenchymal stem cells/multipotent stromal cells [MSCs]), varying amounts of cells were injected into NSG mice and measured immediately after (n = 3 animals per cell dose). (B): After preincubating MSCs for 48 hours in 20% or 1% oxygen, 200,000 cells were injected intramuscularly into NSG mice and luminescence was measured weekly (n = 14 animals per group, with MSCs derived from three different donors). For both (A) and (B), panels on the left show representative images, while average of total experiments is shown on right. Statistical analysis was performed by paired Student’s t test to each individual time point; *, p < .05.