Retroviral gene therapy vectors for prevention of excimer laser-induced corneal haze.
OBJECTIVE
To determine the in vivo efficacy and safety of a retroviral vector bearing an antiproliferative dominant negative mutant cyclin G1 (dnG1) construct, when used for the prevention of corneal haze after phototherapeutic keratectomy (PTK).


METHODS
For in vivo efficacy studies, a 6-mm-diameter, 150-microm-deep transepithelial PTK, performed with a clinical 193-nm ArF excimer laser (VISX Star2, Santa Clara, CA) was performed on the left eyes of 20 adult New Zealand White rabbits. The surgically altered eyes were subsequently treated with eye drops containing: a retroviral vector bearing a dnG1 construct (dnG1; n = 7), a control retroviral vector (null vector) bearing only the neomycin resistance, neo(r), gene (n = 7), or a retroviral vector bearing an antisense cyclin G1 (aG1) construct (n = 6). The time of closure of the corneal epithelial defect was monitored daily with fluorescein staining. Corneal haze was evaluated before surgery and at 2, 3, and 4 weeks after surgery, with a digital imaging system. Biodistribution studies for detection of potential vector dissemination to nontarget organs were conducted by PCR-based assay.


RESULTS
The re-epithelialization rate was similar among treatment groups, with complete closure of the corneal epithelial defect at 72 hours (P > 0.05). Significant corneal haze developed in the null and aG1 vector-treated groups (P <or= 0.05) at 3 to 4 weeks after PTK. In contrast, development of corneal haze was inhibited in the dnG1 vector-treated group when compared with the null vector-treated group (P < 0.05). In parallel, a dramatic reduction to complete abrogation of abnormal extracellular matrix production was noted in the dnG1 vector-treated corneas when compared with the null and aG1 vector-treated groups. Biodistribution studies showed no evidence of vector dissemination in neighboring and distant organs.


CONCLUSIONS
At therapeutic doses, eye drop application of the dnG1 retroviral vector is safe and effective in inhibiting development of corneal haze after PTK in rabbits.
Behrens
Ashley
A
Department of Ophthalmology, Doheny Eye Institute, Los Angeles, California, USA.
Gordon
Erlinda M
EM
Li
Li
L
Liu
Peng X
PX
Chen
Zhenhai
Z
Peng
Hongjun
H
La Bree
Laurie
L
Anderson
W French
WF
Hall
Frederick L
FL
McDonnell
Peter J
PJ
D016475:3T3 Cells; D000818:Animals; D015153:Blotting, Western; D003318:Corneal Opacity / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins / Q000235:genetics* / Q000378:metabolism; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics* / Q000493:pharmacokinetics; D007124:Immunoenzyme Techniques; D054018:Lasers, Excimer; D051379:Mice; D009883:Ophthalmic Solutions; D018903:Photorefractive Keratectomy / Q000009:adverse effects*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D012190:Retroviridae / Q000235:genetics*; D014018:Tissue Distribution; D014161:Transduction, Genetic
C534703:Ccng1 protein, mouse; D056746:Cyclin G; D056766:Cyclin G1; D016213:Cyclins; D009883:Ophthalmic Solutions; D012333:RNA, Messenger