The role of basic fibroblast growth factor in peripheral nerve regeneration.

In the peripheral nervous system regeneration and gradual functional restoration occur following peripheral nerve injury. Growth of regenerating axons depends on the presence of diffusible neurotrophic factors, in addition to the substratum. Neurotrophic factors that are involved in peripheral nerve regeneration include nerve growth factor, brain-derived neurotrophic factor, ciliary neurotrophic factor, glial cell line-derived neurotrophic factor, and interleukin-6. Recent functional and expression studies of basic fibroblast growth factor and its receptors have emphasized a physiological role of these molecules in the peripheral nervous system. Basic fibroblast growth factor and its receptors are constitutively expressed in dorsal root ganglia and the peripheral nerve. These molecules display an upregulation in dorsal root ganglia and in the proximal and distal nerve stumps following peripheral nerve injury. In the ganglia these molecules show a mainly neuronal expression, whereas at the lesion site of the nerve, Schwann cells and invading macrophages represent the main cellular sources of basic fibroblast growth factor and the receptors 1-3. Exogenously applied basic fibroblast growth factor mediates rescue effects on injured sensory neurons and supports neurite outgrowth of transectioned nerves. Regarding the expression patterm and the effects after exogenous administration of basic fibroblast growth factor, this molecule seems to play a physiological role during nerve regeneration. Thus, basic fibroblast growth factor could be a promising candidate to contribute to the development of new therapeutic strategies for the treatment of peripheral nerve injuries.