Perspective: Humanized Pig Models of Bladder Cancer

In situ observation of urothelial responses to NaCl-induced osmotic stress using optical coherence tomography

Significance

We provide the first direct evidence of the urothelial response to water transport through the urothelium, traditionally considered impermeable. Using optical coherence tomography (OCT), we observe that the urothelium absorbs and expels water under varying concentrations of NaCl, challenging long-held views about its impermeability. The discovery that osmotic stress can induce urothelial damage has implications for bladder disorders such as interstitial cystitis and overactive bladder, where urothelial integrity is compromised.

Aim

Traditionally considered impermeable, the urothelium has recently been implicated in water transport due to the presence of aquaporins. Despite this, direct evidence of the urothelial response to water movement through the urothelium remains elusive. We aim to provide such evidence by examining urothelial responses to NaCl solutions using OCT.

Approach

Fresh porcine bladder samples were subjected to OCT imaging to observe urothelial responses under varying osmolarity conditions, using NaCl solutions ranging from 0.31 to 2.07    Osm / L . Urothelial optical pathlength thickness was measured pre-NaCl and post-NaCl application. In addition, histological and scanning electron microscopy (SEM) analyses were conducted to assess cellular integrity and damage.

Results

OCT imaging revealed a significant increase in urothelial optical pathlength thickness following deionized water application, indicative of water absorption. Conversely, exposure to higher osmolarity NaCl solutions resulted in urothelial shrinkage, suggesting water efflux. Histological analysis demonstrated intact cellular structures at lower osmolarities ( 0.31    Osm / L ) but significant cellular disruption at higher concentrations ( ≥ 1.03    Osm / L ). SEM analysis corroborated these findings, showing progressive damage to umbrella cells with increasing osmolarity.

Conclusions

We provide evidence that the urothelium is a dynamic barrier capable of water transport, influenced by osmotic gradients. The observed osmotic-induced urothelial damage may have important implications for the pathophysiology of conditions such as interstitial cystitis and overactive bladder, offering insights into potential diagnostic and therapeutic strategies. These findings warrant further investigation using human tissue.

Oncopig bladder cancer cells recapitulate human bladder cancer treatment responses in vitro

Introduction

Bladder cancer is a common neoplasia of the urinary tract that holds the highest cost of lifelong treatment per patient, highlighting the need for a continuous search for new therapies for the disease. Current bladder cancer models are either imperfect in their ability to translate results to clinical practice (mouse models), or rare and not inducible (canine models). Swine models are an attractive alternative to model the disease due to their similarities with humans on several levels. The Oncopig Cancer Model has been shown to develop tumors that closely resemble human tumors. However, urothelial carcinoma has not yet been studied in this platform.

Methods

We aimed to develop novel Oncopig bladder cancer cell line (BCCL) and investigate whether these urothelial swine cells mimic human bladder cancer cell line (5637 and T24) treatment-responses to cisplatin, doxorubicin, and gemcitabine in vitro.

Results

Results demonstrated consistent treatment responses between Oncopig and human cells in most concentrations tested (p>0.05). Overall, Oncopig cells were more predictive of T24 than 5637 cell therapeutic responses. Microarray analysis also demonstrated similar alterations in expression of apoptotic (GADD45B and TP53INP1) and cytoskeleton-related genes (ZMYM6 and RND1) following gemcitabine exposure between 5637 (human) and Oncopig BCCL cells, indicating apoptosis may be triggered through similar signaling pathways. Molecular docking results indicated that swine and humans had similar Dg values between the chemotherapeutics and their target proteins.

Discussion

Taken together, these results suggest the Oncopig could be an attractive animal to model urothelial carcinoma due to similarities in in vitro therapeutic responses compared to human cells.

A pilot study exploring time- and dose-dependent DNA damage and chromosomal instability caused by benzo[a]pyrene in two urothelial cell types

Environmental and occupational exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with adverse health effects in humans. Uncertainty exists regarding the causation of urinary bladder cancer by benzo[a]pyrene (B[a]P) due to a lack of sufficient data. In this work, we focused on in-vitro DNA damage and the formation of micronuclei and chromosomal aberrations as predictors of cancer risk, applying a wide range of dosages and time periods to quantify the onset, intensity, and duration of the response. We chose two urothelial cell types to compare susceptibility and the ability to increase the malignity of a pre-existing bladder cancer: a cancer cell line (T24) and a pooled sample of primary urinary bladder epithelia cells (PUBEC) from pigs. The highest level of DNA damage assessed by comet assay was observed following 24-h treatment in both cell types, whereas PUBEC cells were clearly more susceptible. Even 4-h treatment induced DNA damage in PUBEC cells with benchmark doses of 0.0027 µM B[a]P and 0.00023 µM after 4-h and 24-h exposure, respectively. Nearly no effect was observed for periods of 48 h. The frequency of micronucleus formation increased more markedly in T24 cells, particularly with 24-h treatment. In PUBEC cells, 48-h exposure notably induced the formation of nucleoplasmic bridges and nuclear buds. Even though only one biological replicate was studied due to the sophisticated study design, our results give a strong indication of the potential of B[a]P to induce and increase malignity in human-relevant cell types.

Autochthonous male urothelial carcinoma immune competent model: from induction to BCG transurethral treatment

To describe a new animal model of autochthonous urothelial cancer (UC) accessible by transurethral catheter in males, from induction to treatment. Seven-week-old male Fischer 344 rats were used. The first 10 animals were used to overcome and standardize the technical challenges of safe transurethral catheterization of male rats. The remaining 14 animals underwent intravesical N-Methyl-Nitrosourea (MNU) instillation for UC induction, of which six were randomized to undergo intravesical BCG treatment. The stretched male rat urethra travels 35 mm in a tortuous "S" shaped trajectory with a 180° angle behind the pubic bone, safely traversed by a 20G 36" 0.8 mm epidural catheter in a stretched, straightened urethra inserted after anterior dilation of the penile urethra with a 24G IV catheter. Histopathologic analysis of the urinary bladder demonstrated Stage pT1, pTa, and pTis lesions in the 8 controls, all with increased cell proliferation by Ki-67 expression and no pT1 or pTis in the animals 6 treated with BCG. This pioneering study describes an autochthonous, effective, and accessible transurethral animal model of immune-competent UC in males, and may help with understanding of the biology, immunology, and treatment of UC, which predominates in males.