IGF-1 gene transfer into denervated rat laryngeal muscle.
OBJECTIVE
To demonstrate gene transfer in rat laryngeal muscle using a reporter gene, beta-galactosidase, and a muscle-specific expression system containing the human IGF-1 (hIGF-1) gene sequence and to investigate the myotrophic and neurotrophic effects of hIGF-1 gene transfer in denervated rat laryngeal muscle.


METHODS
In 8 adult rats, a polyvinyl-based formulation containing beta-galactosidase DNA was injected into denervated thyroarytenoid muscle. Twelve animals were similarly administered a polyvinyl-based formulation containing a muscle-specific expression system and hIGF-1 DNA. Twelve animals were injected with isotonic sodium chloride solution, and all animals survived for 1 month. The production of beta-galactosidase and hIGF-1 was detected using immunohistochemical techniques. The effects of hIGF-1 on motor endplates and nerve sprouting were assessed using cholinesterase or silver staining and immunostaining for growth-associated protein (GAP-43). mals by immunostaining, X-gal histochemical staining, or both. In frozen section specimens, hIGF-1 immunoreactivity was positive in 3 of 8 animals. In sequential sections, GAP-43 was localized to areas of hIGF-1 expression in 2 of the 3 hIGF-1-positive specimens. Increased nerve sprouting and motor endplate contact occurred in 2 of 4 animals treated with hIGF-1.


CONCLUSIONS
Gene transfer into laryngeal muscle was demonstrated using a polyvinyl-based formulation containing a muscle-specific gene expression system. Preliminary findings indicate a positive effect on motor endplates, nerve sprouting, and the expression of GAP-43 in animals treated with the hIGF-1 vector. This study establishes a foundation for investigating hIGF-1 gene transfer as a novel treatment of laryngeal paralysis. Further studies are necessary to quantify myotrophic and neurotrophic effects and to establish therapeutic benefit.
Flint
P W
PW
Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins School of Medicine, Baltimore, MD 21203-6402, USA. pflint@jhmi.edu
Shiotani
A
A
O'Malley
B W
BW
D000818:Animals; D018014:Gene Transfer Techniques; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007821:Laryngeal Muscles / Q000378:metabolism*; D010957:Plasmids; D051381:Rats; D014162:Transfection; D014826:Vocal Cord Paralysis / Q000628:therapy; D001616:beta-Galactosidase
D007334:Insulin-Like Growth Factor I; D001616:beta-Galactosidase