Neuregulin 1 (NRG1) and epidermal growth factor recep-tor (ErbB) signaling pathways control Schwann cells during axonal regeneration in an injured peripheral nervous system. We investigated whether a persistent supply of recombinant NRG1 to the injury site could improve axonal growth and recovery of sensory and mo-tor functions in rats during nerve regeneration. We generated a recombinant adenovirus expressing a se-creted form of EGF-like domain from Heregulinβ(sHRGβE-Ad). This virus, sHRGβE- Ad allowed for the secretion of 30-50 ng of small sHRGβE peptides per 10^7-8 virus particle outside cells and was able to phosphorylate ErbB receptors. Transduction of the con-centrated sHRGβE-Ad into an axotomy model of sciatic nerve damage caused an effective promotion of nerve regeneration, as shown by histological features of the axons and Schwann cells, as well as increased ex-pression of neurofilaments, GAP43 and S100 in the distal stump of the injury site. This result is consistent with longer axon lengths and thicker calibers observed in the sHRGβE-Ad treated animals. Furthermore, sensory and motor functions were significantly improved in sHRGβE-Ad treated animals when evaluated by a behavioral test. These results suggest a therapeutic potential for sHRGβE-Ad in treatment of peripheral nerve injury.

Keywords: adenovirus, axonal growth, HRG