Figure 3.

The principles of testing MSC homing in mechanically and/or nutritionally stressed IVDs. (a) Principle of homing using in vitro Boyden chamber assays (b) Testing of homing in 3D organ culture models (c) Evidence from in vivo animal models. Inlet 1: confocal laser scanning pictures (cLSM) of MSC homing experiment with differently labeled MSCs (green, red, and yellow) that were added at various time points during the experiment (A) a transverse section of a bovine IVD without endplates (B–D) close-up pictures at the outer AF (based on Illien-Jünger et al. [93]) Inlet 2: fluorescent image illustrating single stained MSCs in the outer periphery of the AF after 12 weeks post-injection, 10× magnification (based on Sakai et al. [92]). Inlet 2 was reproduced with copyright approval from the publisher.