Whilst there is an increased understanding of the cell biology of nerve regeneration, it remains unclear
whether there is a direct interrelationship between vascularisation and efficacy of nerve regeneration within a
nerve conduit. To establish this is important as in clinical surgery peripheral nerve conduit grafting has been
widely investigated as a possible alternative to the use of nerve autografts. The aim of this study was to
assess whether vascular endothelial growth factor (VEGF), a highly specific endothelial cell mitogen, can
enhance vascularisation and, indirectly, axonal regeneration within a silicone nerve regeneration chamber.
Chambers containing VEGF (500–700 ng/ml) in a laminin-based gel (Matrigel) were inserted into 1 cm rat
sciatic nerve defects and nerve regeneration examined in relation to angiogenesis between 5 and 180 d.
Longitudinal sections were stained with antibodies against endothelial cells (RECA-1), axons (neurofilament)
and Schwann cells (S-100) to follow the progression of vascular and neural elements. Computerised image
analysis demonstrated that the addition of VEGF significantly increased blood vessel penetration within the
chamber from d 5, and by d 10 this correlated with an increase of axonal regeneration and Schwann cell
migration. The pattern of increased nerve regeneration due to VEGF administration was maintained up to
180 d, when myelinated axon counts were increased by 78% compared with plain Matrigel control.
Furthermore the dose-response of blood vessel regeneration to VEGF was clearly reflected in the increase of
axonal regrowth and Schwann cell proliferation, indicating the close relationship between regenerating
nerves and blood vessels within the chamber. Target organ reinnervation was enhanced by VEGF at 180 d
as measured through the recovery of gastrocnemius muscle weights and footpad axonal terminal density, the
latter showing a significant increase over controls (P < 0.05). The results demonstrate an overall relationship
between increased vascularisation and enhanced nerve regeneration within an acellular conduit, and
highlight the interdependence of the 2 processes.