Keratinocyte growth factor induced epithelial proliferation facilitates retroviral-mediated gene transfer to distal lung epithelia in vivo.
BACKGROUND
Cell proliferation, vector titer and accessibility of target cells represent hurdles for efficient gene transfer to lung epithelia in vivo using recombinant murine leukemia (MuLV)-based retroviruses. We tested the hypothesis that the pulmonary epithelium is susceptible to retroviral-mediated gene transfer when stimulated to proliferate by a mitogen, keratinocyte growth factor (KGF).


METHODS
Rats received keratinocyte growth factor (KGF, 2.5 micrograms/g x 4 doses, two consecutive days) intratracheally followed by high titer amphotropic retrovirus expressing beta-galactosidase. Gene transfer was assessed five days later.


RESULTS
KGF stimulated transient proliferation in the bronchiolar and alveolar epithelia (30-40% PCNA positive cells at peak) which decreased to background levels seven days after administration. Gene transfer to epithelia (X-Gal positive cells) occurred more frequently in KGF treated rats, but proliferation exceeded the level of gene transfer. X-gal positive cells were noted in the alveolar epithelium and occasionally in the bronchiolar epithelium. In order to understand the discrepancy between the number of proliferating and transduced cells, primary rat tracheal epithelium cultured at the air-liquid interface was infected from either the apical or basolateral side. Gene transfer was achieved only through basolateral application of vector, suggesting that epithelial polarity represents a barrier to MuLV-based lung gene transfer in vivo.


CONCLUSIONS
KGF transiently stimulates epithelial proliferation in vivo, facilitating MuLV-based gene transfer. Retroviral vectors may encounter multiple barriers which have evolved to defend the lung from infections.
Wang
G
G
Department of Pediatrics, University of Iowa College of Medicine, Iowa City 52242, USA.
Slepushkin
V A
VA
Bodner
M
M
Zabner
J
J
van Es
H H
HH
Thomas
P
P
Jolly
D J
DJ
Davidson
B L
BL
McCray
P B
PB
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D016764:Cell Polarity; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D009052:Leukemia Virus, Murine / Q000235:genetics*; D008168:Lung / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D051379:Mice; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011991:Receptors, Virus / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D001616:beta-Galactosidase / Q000235:genetics
C496463:FGF10 protein, human; C496453:FGF7 protein, human; C496464:Fgf10 protein, mouse; C496465:Fgf10 protein, rat; C496454:Fgf7 protein, mouse; C496455:Fgf7 protein, rat; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D018809:Proliferating Cell Nuclear Antigen; D011991:Receptors, Virus; D011994:Recombinant Proteins; C067981:leukemia virus receptor, gibbon ape; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D001616:beta-Galactosidase