Failure of axons to regenerate across GDACNTF or GRP transplanted dorsal column injuries. (a) Biotinylated dextran amine (BDA)-labeled endogenous, ascending dorsal column axons (green) fail to cross GDACNTF-transplanted injury sites and instead form dystrophic endings within caudal injury margins. While a few axons sprout towards the injury center, BDA+ axons are rarely detected beyond the injury/transplantation site at 8 days post-injury/transplantation. Scale bar 200 μm. (b) In contrast, transplanted GDAsBMP support extensive axon growth across dorsal column injuries at 8 days after injury/transplantation. Scale bar 200 μm. (c) Quantification of numbers of regenerating BDA+ axons in GDA- or GRP-transplanted dorsal column white matter at 8 days after injury and transplantation. BDA-labeled axons were counted in every third sagittally oriented section within the injury center and at points 0.5 mm, 1.5 mm and 5 mm rostral to the injury site and within the dorsal column nuclei (DCN). Note that 55% of BDA+ axons reached the centers of GDABMP-transplanted injuries, and 36% to 0.5 mm beyond the injury site. After GDACNTF or GRP transplantation, however, only 7% and 5.3% of BDA+ axons, respectively, were observed within injury centers, with only 4.6% and 4.2% of the axons observed at 0.5 mm beyond the injury site. No BDA+ axons were detected beyond 1.5 mm rostral to the injury site in GDACNTF- or GRP-transplanted spinal cords. Error bars represent 1 SD.
Davies et al. Journal of Biology 2008 7:24 doi:10.1186/jbiol85