Penttilä H, Waris T,
Ashammakhi N, Vanhatalo S.
Abstract
Post-operative survival of arterial grafts is a major challenge in transplantation
surgery. The vasospasms remain an important cause of graft failures,
while the understanding about post-operative changes in arterial graft
innervation is negligible.
This study was performed to characterize the neuronal degeneration and
regeneration in femoral artery grafts transplanted to carotid artery
in rats. Perivascular innervation was assessed at 1, 3 and 7 days, as
well as at 1, 3 and 5 months postoperatively. We studied by immunohistochemistry
markers for neuronal cytoskeleton (neurofilaments and growth associated
protein-43), parasympathetic innervation (vasoactive intestinal peptide
(VIP) and neuronal nitrix oxide sybthase (nNOS)), sympathetic innervation
(tyrosine hydroxylase), as well as endothelial and incudible NOS isoforms.
During neuronal degeneration, neuropeptide VIP disappeared within the
first postoperative day, enzymes (nNOS and TH) were vanished by the day
7, and cytoskeletal neurofilament essentially diappeared after one week.
During regeneration, the most robust axonal growth, as visualized by
GAP-43 immunoreactivity, was observed at one month, followed by gradual
increase in transmitter markers upto three months. Neurofilaments increased
throughout the five month follow-up period. Major portion of the re-innervating
nerves proceeded from the proximal carotid artery (host) distally to
the graft. The primary pathway of axonal regrowth was in arterial adventitial
layer. The innervation density appeared to be denser in the graft than
in the host.
Our findings suggest that i) the main sequence of neuronal degeneration
and regeneration in vascular grafts is essentially similar to that reported
in other tissues, ii) re-innervation of the arterial graft comes mainly
from the host artery, iii) and the innervation pattern in the graft is
different from the host.
Keywords: Arterial graft, transplantation, innervation, degeneration,
regeneration, vasospasm, sympathetic innervation, free flaps, microsurgery
