Triple label for CTB-labeled sensory axons (red), implanted MSCs (green, expressing GFP), and astrocytes (GFAP, blue). (A,B) MSCs form a cellular substrate in the lesion site that supports sensory axon regeneration. Green labeling identifies grafted cells that primarily remain within the lesion site, and migrate from the lesion site for only very short distances (panels A, B). Blue labeling demonstrates glial reactivity at lesion margins. (B-D) Sensory axons regenerate beyond the graft/implant site and into glial scar tissue beyond the graft (arrowheads). Panel C is from dorsal white matter 1 mm beyond (rostral to) the MSC graft. Regenerating sensory axons in white matter (D) branch extensively by rostral NT-3 injection site. Scale bar = 35 µm in A, B, 17 µm in C, D.