Nerve regeneration in a 'pseudo-nerve' graft created in a silicone tube.
The pseudo-nerve, which contains longitudinal Schwann cell columns without axons and surrounded by perineurium-like tissue but no axons (Q. Zhao, L.B. Dahlin, M. Kanje, G. Lundborg, Brain Res. 592 (1992) 106-114), was applied as a graft to repair nerve defect in rats. Creation of the pseudo-nerve was accomplished by inserting the proximal and distal stumps of a cut sciatic nerve into a silicone tube. The proximal insert was cut far proximally to prevent axons from entering the tube. After 4 weeks, the pseudo-nerve was harvested, trimmed into a 10-mm long graft and transplanted into a corresponding defect of the contralateral sciatic nerve. Nerve regeneration through the pseudo-nerve was examined by pinch reflex test and neurofilament staining after 6 days or by morphology after 4, 6 or 8 weeks. The results showed that the pseudo-nerve could induce nerve regeneration to a similar extend as a real nerve graft. The neurobiological composition of the pseudo-nerve and the factors influencing its formation were also studied. By double staining of S-100 and laminin we found that the longitudinally organized Schwann cell columns in the pseudo-nerve were surrounded by basal laminae and ensheathed by a layer of vascularized perineurium-like tissue. Macrophages (ED1 and ED2) and their products interleukin-1beta (IL-1beta) and transforming growth factor-beta1 (TGF-beta1) were constantly present in the pseudo-nerve. Besides, the size of tube was a crucial factor in influencing pseudo-nerve formation, e.g. a thicker pseudo-nerve was formed in tubes with larger diameters or shorter gap lengths. No pseudo-nerve was formed when the gap was 15 mm long. When both proximal and distal inserts were isolated nerve segments the pseudo-nerve was still formed but thin, probably because of compromised vascular supply. Taken together, the results suggested that the pseudo-nerve contains the essential neurobiological elements to induce successful axonal elongation.
Zhao
Q
Q
Department of Hand Surgery, Malmö University Hospital, Lund University, Sweden. qing.zhao@exp.mas.lu.se
Lundborg
G
G
Danielsen
N
N
Bjursten
L M
LM
Dahlin
L B
LB
D000818:Animals; D001369:Axons / Q000502:physiology; D004867:Equipment Design; D004864:Equipment and Supplies; D005260:Female; D007375:Interleukin-1 / Q000378:metabolism; D008264:Macrophages / Q000166:cytology; D018919:Neovascularization, Physiologic / Q000502:physiology; D009416:Nerve Regeneration / Q000502:physiology*; D009417:Nerve Tissue / Q000098:blood supply / Q000166:cytology / Q000637:transplantation*; D010525:Peripheral Nerves / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012583:Schwann Cells / Q000502:physiology*; D012828:Silicones; D016212:Transforming Growth Factor beta / Q000378:metabolism
D007375:Interleukin-1; D012828:Silicones; D016212:Transforming Growth Factor beta