Figure 4
From: Imaging axon regeneration within synthetic nerve conduits
Documenting the growth-promoting effect of neurotrophic factors during early-stage axonal regeneration within conduits. (A) Following sciatic nerve transections pre-treated chitosan conduits filled with PuraMatrix that had been supplemented with a cocktail of NTFs (final concentration: 2 µg/ml each of NGF, BDNF, NT-3, and GDNF) were implanted in the animals. After a regeneration period of 14 days the lesioned nerve was dissected and the nerve-conduit assembly then fixed, cleared and imaged by long working distance confocal microscopy. Excessive axonal sprouting immediately distal to the lesion site is indicated with a white arrow, backward-projecting axons within the proximal stump are marked with white arrow heads. The lesion plane is indicated with a red bar, the (y, z) section plane with a dashed red bar (see insert). The conduit’s silhouette is marked with a dashed white line. Scale bar length is 500 µm. (B) In the control group no NTFs were added to the PuraMatrix. (C) Quantification of the regenerative axonal growth at the lesion site, in the presence of NTFs and in their absence. Excessive axonal sprouting and the backward-projecting axons are marked on the NTF treatment curve. The curves from 10 independent experiments were pooled in each group. Data are presented as mean values at each incremental position. Solid lines have been smoothed over 50 µm intervals. (D) Statistical analyses were performed for the proximal and the distal segments, as well as for each of the three 1000 µm segments. n = 10 for each experimental group. Data represent mean ± SD. p values are indicated. *p ≤ 0.05, **p ≤ 0.01.
