Complete spinal cord transection treated by implantation of a reinforced synthetic hydrogel channel results in syringomyelia and caudal migration of the rostral stump.
OBJECTIVE
Previously, we reported that synthetic poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (PHEMA-MMA) channels promoted regeneration of a small number of axons from brainstem motor nuclei yet provided limited functional recovery after complete spinal cord transection at T8 in rats. However, we found that these modulus channels partially collapsed over time. Therefore, we synthesized coil-reinforced PHEMA or PHEMA-MMA channels with greater elastic moduli and introduced a new spinal fixation technique to prevent collapse. We also assessed axonal regeneration within the new channels containing a cocktail of autologous peripheral nerve grafts, fibrin matrix, and acidic fibroblast growth factor.


METHODS
After spinal cord transection, rats were divided into six groups: Groups 1 and 2 had either a PHEMA or PHEMA-MMA reinforced channel implanted between the stumps of the transected spinal cord with the cocktail; Groups 3 and 4 had either an unfilled reinforced PHEMA or PHEMA-MMA channel similarly implanted; Group 5 had an spinal cord transection without channel implanted, and Group 6 underwent the identical procedure to Group 1, but rats were sacrificed by 8 weeks for early histological assessment. Groups 1 to 5 were sacrificed at 18 weeks.


RESULTS
There was no channel collapse at any time. However, there was no improvement in axonal regeneration or functional recovery among Groups 1 to 4 because of the unexpected development of syringomyelia and caudal migration of the rostral stump. Functional recovery was better in Groups 1 to 4 compared with Group 5 (P < 0.05).


CONCLUSIONS
The use of channels to enhance regeneration of axons is promising; however, improvement of the design of the channels is required.
Nomura
Hiroshi
H
Toronto Western Research Institute, Toronto Western Hospital,Toronto, Canada.
Katayama
Yusuke
Y
Shoichet
Molly S
MS
Tator
Charles H
CH
D000818:Animals; D001369:Axons; D004867:Equipment Design; D005260:Female; D005337:Fibrin / Q000378:metabolism; D016220:Fibroblast Growth Factor 1 / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008689:Methacrylates; D009416:Nerve Regeneration; D010525:Peripheral Nerves / Q000637:transplantation; D011102:Polyhydroxyethyl Methacrylate; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function; D013119:Spinal Cord Injuries / Q000150:complications / Q000378:metabolism / Q000503:physiopathology / Q000601:surgery*; D013595:Syringomyelia / Q000209:etiology*; D013997:Time Factors
D008689:Methacrylates; D016220:Fibroblast Growth Factor 1; D011102:Polyhydroxyethyl Methacrylate; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C059480:poly(hydroxyethyl methacrylate-methacrylic acid)hydrogel; D005337:Fibrin