Towards gene therapy in prosthesis loosening: efficient killing of interface cells by gene-directed enzyme prodrug therapy with nitroreductase and the prodrug CB1954.
BACKGROUND
Loosening is a major complication in prosthesis surgery. To stabilize loosened orthopedic implants, the interface tissue surrounding the implant must be removed. As an alternative to manual removal, we explored the possibility of removing the tissue by gene-directed enzyme prodrug therapy. In the current study we investigated whether interface cells can be transduced by an HAdV-5 vector carrying the E.coli-derived nitroreductase gene and sensitized to the prodrug CB1954.


METHODS
The gene transfer efficiency into cultures of diploid human interface cells was tested by exposing these cells to various concentrations of Ad.CMV.LacZ. Subsequently, we studied the susceptibility of cells to the NTR/CB1954 combination.


RESULTS
X-gal staining of the Ad.CMV.LacZ-transduced cell cultures revealed that, at 200 plaque-forming units (pfu)/cell, 74% of the cells expressed the LacZ gene. Infection with an NTR construct in interface cell lines resulted in a 60-fold sensitization to the prodrug CB1954. In addition we observed that iotrolan (Isovist) contrast medium had no effect on viability of the cells. However, the presence of the contrast medium completely inhibited adenovirus-mediated gene transfer.


CONCLUSIONS
From these data we conclude that HAdV-5-based vectors carrying nitroreductase can be used to sensitize interface tissue. Instead of contrast medium the clinical protocol will use an alternative visualization procedure.
Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands. j.k.de_poorter@LUMC.nl
Jolanda J
JJ
de Poorter
Tanja C A
TC
Tolboom
Martijn J W E
MJ
Rabelink
Elsbet
E
Pieterman
Rob C
RC
Hoeben
Rob G H H
RG
Nelissen
Tom W J
TW
Huizinga
D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000368:Aged; D000970:Antineoplastic Agents / Q000378:metabolism / Q000633:toxicity*; D001388:Aziridines / Q000378:metabolism / Q000633:toxicity*; D016923:Cell Death; D002470:Cell Survival; D002478:Cells, Cultured / Q000187:drug effects; D003287:Contrast Media / Q000378:metabolism; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D006622:Hip Prosthesis; D006801:Humans; D009601:Nitroreductases / Q000235:genetics / Q000378:metabolism; D011355:Prodrugs / Q000378:metabolism*; D011475:Prosthesis Failure; D014161:Transduction, Genetic; D014283:Triiodobenzoic Acids / Q000378:metabolism
D000970:Antineoplastic Agents; D001388:Aziridines; D003287:Contrast Media; D011355:Prodrugs; D014283:Triiodobenzoic Acids; C033300:iotrolan; C100099:tretazicar; D009601:Nitroreductases