Topical chemotherapy in human urothelial carcinoma explants: a novel translational tool for preclinical evaluation of experimental intravesical therapies.
BACKGROUND
Urothelial carcinoma (UC) is associated with a high local recurrence rate despite intravesical therapy. There is a lack of representative preclinical models for standardized testing of novel experimental therapies.


OBJECTIVE
To develop an ex vivo model for human UC and to evaluate its ability to generate reproducible and reliable results when testing cytotoxic agents.


METHODS
Normal human urothelium (NHU) and bladder UC explants were collected from patients treated at our institution. A total of 195 surgical explants were cultured on a gelatine matrix. Tissue viability was regularly assessed using nicotinamide adenine dinucleotide (NADH) diaphorase enzymehistochemistry. Topical paclitaxel (PTX) or mitomycin C (MMC) chemotherapy was performed in a subset of 45 UC specimens.


METHODS
All patients underwent radical cystectomy (RC) or primary transurethral resection (TUR) of a bladder UC.


METHODS
Triple immunofluorescence (pan-cytokeratin [pan-CK]; 4',6-diamidin-2'-phenylindol-dihydrochloride [DAPI]; terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling [TUNEL]) and caspase-3 staining of paraffin sections was performed. Proliferation rates were assessed using Ki-67 labelling indices. Apoptosis (percent) was quantified in representative tissue areas to characterize culture stability and to assess antineoplastic effects.


CONCLUSIONS
No signs of necrosis and no significant changes in apoptosis were observed during the first 12 d of culture. Of all explants, 88.5% were vital after 20 d. In a highly reproducible fashion, topical chemotherapy resulted in significantly increased apoptosis (37.4% [19.0-75.0%] for PTX and 36.2% [18.8-46.7%] for MMC) compared with controls (7.5% [3.0-26.8%]; p<0.001]). No statistically significant difference was observed regarding the effects of the two chemotherapeutic agents (p=0.119).


CONCLUSIONS
The presented human ex vivo model takes UC heterogeneity into account and serves as a valuable translational tool. It offers an attractive alternative to preclinical cell line experiments or animal models and may even be used for prospective toxicity and drug efficacy tests in individual patients.
Bolenz
Christian
C
Department of Urology, Mannheim Medical Centre, University of Heidelberg, Germany. christian.bolenz@uro.ma.uni-heidelberg.de
Ikinger
Eva-Maria
EM
Ströbel
Philipp
P
Trojan
Lutz
L
Steidler
Annette
A
Fernández
Mario I
MI
Honeck
Patrick
P
Gabriel
Ute
U
Weiss
Christel
C
Grobholz
Rainer
R
Alken
Peter
P
Michel
Maurice Stephan
MS
D000283:Administration, Intravesical; D000287:Administration, Topical; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D002295:Carcinoma, Transitional Cell / Q000188:drug therapy*; D004354:Drug Screening Assays, Antitumor; D005240:Feasibility Studies; D006801:Humans; D046509:Tissue Culture Techniques; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy*
D000970:Antineoplastic Agents