Presence of trans-synaptic neurons derived from olfactory mucosa transplanted after spinal cord injury.
METHODS
Using biotinylated dextran amine (BDA) and wheat germ agglutinin (WGA) tracers, we measured the effectiveness of olfactory mucosa (OM) transplantation as a scaffold in a rat model of chronic spinal cord injury (SCI).


OBJECTIVE
We examined whether OM transplantation for chronic SCI in rats results in reconstruction of neuronal pathways by both regeneration of the remaining axons and supply of OM-derived trans-synaptic neurons.


BACKGROUND
OM is one of the ideal scaffolds for axonal regeneration after chronic SCI.


METHODS
Rats received a mild contusion at vertebral level T6-T7. Two weeks after SCI, enhanced green fluorescent protein rat-derived OM, respiratory mucosa, and phosphate-buffered saline were transplanted into each group of SCI rats. Ten weeks after SCI, BDA was injected into the right sensorimotor cortex. Eleven weeks after SCI, WGA was injected into the L1-L2 posterior column to label the corticospinal tract retrogradely and trans-synaptically. Twelve weeks after SCI, rats were killed and their spinal cords were divided into cervical (area a), thoracic-injured (area b), and lower thoracic portions (area c). Immunohistochemically, sections of area (b) were evaluated by counting cells positive for enhanced green fluorescent protein, 4',6-diamidino-2-phenylindole, WGA, and BDA (OM and respiratory mucosa groups). Axonal regenerations were estimated by counting WGA- and BDA-positive dots in transverse sections of area (a) and area (c).


RESULTS
Compared with respiratory mucosa and phosphate-buffered saline transplantation, OM transplantation increased the number of WGA-positive dots in area (a), and the number of BDA-positive dots in area (c) was more after OM transplantation than after phosphate-buffered saline transplantation. Furthermore, the number of quadruple-positive cells in area (b) was much higher after OM transplantation.


CONCLUSIONS
Our results provide both indirect and direct evidence for the presence of trans-synaptic neurons. OM transplantation in rats with chronic SCI resulted in reconstruction of neural pathways by both providing trans-synaptic neurons and supporting regeneration of remaining axons. The olfactory mucosa is thought to be an efficacious scaffold to produce the relay neuron in chronic spinal cord injury.
From the Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Takashi
T
Moriwaki
Koichi
K
Iwatsuki
Noriko
N
Mochizuki-Oda
Yu-ichiro
Y
Ohnishi
Masahiro
M
Ishihara
Masao
M
Umegaki
Koshi
K
Ninomiya
Toshiki
T
Yoshimine
D000818:Animals; D001369:Axons / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D018613:Microscopy, Confocal; D009416:Nerve Regeneration; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D009831:Olfactory Mucosa / Q000166:cytology* / Q000637:transplantation; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000503:physiopathology / Q000601:surgery; D013119:Spinal Cord Injuries / Q000503:physiopathology* / Q000601:surgery; D009435:Synaptic Transmission; D016896:Treatment Outcome
D049452:Green Fluorescent Proteins