Fig. 6. Nerve regeneration and sensorimotor reintegration in MDT-exposed animals are associated with gain of function in regenerated hindlimbs.

(A) Distal (left column) and proximal (right column) sections of the regenerates were labeled with antibodies for an axonal nerve marker, AAT (red), and counterstained with DAPI (blue). Sections obtained from regenerates exposed to the MDT immediately after amputation displayed significantly more AAT⁺ bundles (B) [N = 10 MDT, n = 8 BD, n = 6 ND, Kruskal-Wallis H(3,24) = 15.12, P < 0.005] with wider diameter (C) [Mann-Whitney U(3,24) = 11.74, P = 0.0028] than those sections obtained from ND or BD-exposed animals. (D) Sensorimotor reintegration as assessed by VF filaments applied to the distal tip of the regenerate showed gain of function in the MDT group similar to that of unamputated (wild-type) limbs from ND animals. (E) MDT animals displayed a reliable restoration of sensorimotor function as evidenced by a stimulation force threshold (0g) matching uninjured (UI) animals (P > 0.05). BD animal sensorimotor function was highly variable, with subsets displaying a complete lack of response (top cluster), a partial response (middle cluster), or full restoration of function (bottom cluster). ND animals universally displayed a total lack of response to stimulation. (F) SKI gene expression, which is associated with peripheral myelination and glial cell proliferation, was up-regulated at 11 and 24 hpa but not at 7 dpa. ETV1 gene expression, which is associated with the peripheral glial repair response to injury, was down-regulated at 24 hpa and later up-regulated at 7 dpa. Means and SD are presented. ***P < 0.001.