gms | German Medical Science

Objective: Recently it has been demonstrated that a C-terminal peptide fragment covering amino acid 154–182 of the Rho-inactivating C3 transferase (C3bot) from Clostridium botulinum, although transferase deficient, triggers dendritic and axonal growth and branching and increases synaptic connectivity of neurons in organotypic cultures in vitro (Höltje et al. FASEB 2009). Here we investigate the impact of a truncated C3-peptide on peripheral nerve regeneration utilizing different peripheral nerve lesion models.

Methods: In a pilot study 10 mm sciatic nerve gaps in adult rats were bridged by nerve autotransplants and 20 µl of a C3-peptide solution (40 µM) were injected into the proximal and distal sutures. Injections of vehicle alone served as control.

Motor function of distal hind paw muscles was weekly estimated using the Static Sciatic Index (SSI, Bozkurt et al. J Neurosci Meth 2008) over 4 and 10 weeks (n=20 animals per condition, each). By end of the observation time electrodiagnostic measurements revealed nerve conduction velocities. Muscles masses of lower limb muscles were determined. Regenerated nerve tissue was harvested, epon embedded and subjected to histomorphometrical analyses.

To further elucidate the regeneration promoting potential of C3-petide fragments, in a second study nerve crush lesions were treated with C3-peptide in three different concentrations (8 µM, 40 µM, 200 µM) and compared to treatment with vehicle alone (negative control), nerve growth factor (25 µg/ml, positive control 1), or C3 wildtype protein (positive control 2).

Results: Preliminary results indicate an improved motor recovery after C3-peptide treatment, demonstrated by higher SSI-values and significantly increased ratios of nerve conduction velocities ipsilateral/contralateral in C3-peptide treated animals compared to vehicle controls. Further analyses are currently on the way to analyse functional and histomorphological regeneration parameters in more detail.

Conclusions: C3-peptide fragments could provide new therapeutic options to support functional recovery after peripheral nerve reconstruction. This is highlighted by a phase two-clinical study of C3-wildtype derivates to improve regeneration after spinal cord injury.

Financial support: Hochschulinterne Leistungförderung (HiLF) of the Hannover Medical School (to S.H.) and Förderpreis der Stiftung Sibylle Assmuss (to K.H.)