One of the limitations in IC research is actually being able to study bladder lining cells for an indepth period of time. As Dr. Phil Hanno says in his editorial below, researchers were limited by the life span of the cells they captured through bladder biopsies. Researchers have now created a line of human urothelial cells that are sensitive to the antiproliferative factor and may mimic IC. It's interesting though, admittedly, VERY arcane science! - Jill

Editor's Commentary - An hTERT-immortalized human urothelial cell line that responds to anti-proliferative factor
Mon, 21 March 2011 | Philip M. Hanno, MD

Human Urothelial Cell Line Sensitive to APF Isolated

Re-expression of the human telomerase reverse transcriptase (hTERT) has been employed as an effective strategy for immortalization of primary cultures of various different cell types. hTERT encodes the catalytic subunit of telomerase and prevents age-induced shortening of telomeres, thereby preventing replicative senescence. Resulting cell lines can be non-tumorigenic and may not display chromosomal abnormalities.

Jayoung Kim and colleagues from Boston, Cleveland, and Baltimore have now described the isolation and characterization of a novel hTERT-immortalized, nontransformed human urothelial cell line (TRT-HU1). Features of this cell line include sensitivity to the anti-proliferative peptide APF, which has been implicated in the pathogenesis of BPS/IC and a chromosomal deletion at 9p, an early event in the development of urothelial carcinoma.

Antiproliferative factor (APF) was purified from the supernatant of bladder epithelial cells explanted from a patient diagnosed with BPS/IC. Mock APF was prepared using cells from an age, race, and gender-matched normal control subjected to the same purification procedure. Exposure of TRT-HU1 cells to APF led to reduced cell proliferation by -45% as compared to control. APF treatment of TRT-HU1 cells resulted in increased p53 expression consistent with previous demonstration of P53 upregulation as a key component in the antiproliferative response of bladder epithelial cells to APF.

The authors note that this is the first demonstration that an hTERT-immortalized urothelial cell line responds to APF. They believe that this may represent an important advance in studies aimed at understanding the molecular basis of BPS/IC. Previous studies have relied on primary cultures isolated from patient biopsies and have been limited by the finite lifespan of the cells. Development of an immortalized cell line that responds to APF will greatly facilitate larger scale analyses such as metabolomics approaches or those employing state-of-the-art quantitative proteomics that rely on isotopic labeling of cultures through many population doublings. They write that in future experiments, a comparison of gene expression patterns between primary non-immortalized explanted c ells from BPS/IC patients and APF-treated TRT-HU1 cells will help to confirm the utility of these immortalized cells for delineating the molecular basis of BPS/IC.

These cells may serve as a valuable tool for studies of normal urothelial biology, as well as those aimed at investigating early events in development of bladder cancer and other diseases affecting the urothelium.

Reference: Kim J, Ji M, DiDonato JA, Rackley RR, Kuang M, Sadhukhan PC, Mauney JR, Keay SK, Freeman MR, Liou LS, Adam RM
In Vitro Cell Dev Biol Anim. 2011 Jan;47(1):2-9