Paracrine Signaling from a Three-Dimensional Model of Bladder Carcinoma and from Normal Bladder Switch the Phenotype of Stromal Fibroblasts

SIMPLE SUMMARY: The aim of this work was to create a bladder carcinoma model to study the signals secreted by carcinoma cells in a in vivo-like context and how this molecular signaling can alter stromal fibroblasts. Our model is based on decellularized organ fragments (scaffolds) that aim to preserve the complexity of the native extracellular matrix of the bladder. Primary epithelial cells isolated from human bladder carcinoma were seeded on the scaffolds. We found that those cells showed a similar gene expression pattern when seeded on the scaffolds or on monolayer cultures. However, the secreted pattern of key growth factors was significantly different. Only the combination of factors secreted by carcinoma cells seeded on the scaffolds, but not the carcinoma cells seeded on plastic, was able to induce a pro-inflammatory or myofibroblast phenotype. This model allows one to decipher the paracrine pathways of bladder carcinoma in a defined in vitro system. ABSTRACT: We present a three-dimensional model based on acellular scaffolds to recreate bladder carcinoma in vitro that closely describes the in vivo behavior of carcinoma cells. The integrity of the basement membrane and protein composition of the bladder scaffolds were examined by Laminin immunostaining and LC–MS/MS. Human primary bladder carcinoma cells were then grown on standard monolayer cultures and also seeded on the bladder scaffolds. Apparently, carcinoma cells adhered to the scaffold basement membrane and created a contiguous one-layer epithelium (engineered micro-carcinomas (EMCs)). Surprisingly, the gene expression pattern displayed by EMCs was similar to the profile expressed by the carcinoma cells cultured on plastic. However, the pattern of secreted growth factors was significantly different, as VEGF, FGF, and PIGF were secreted at higher levels by EMCs. We found that only the combination of factors secreted by EMCs, but not the carcinoma cells grown on plastic dishes, was able to induce either the pro-inflammatory phenotype or the myofibroblast phenotype depending on the concentration of the secreted factors. We found that the pro-inflammatory phenotype could be reversed. We propose a unique platform that allows one to decipher the paracrine signaling of bladder carcinoma and how this molecular signaling can switch the phenotypes of fibroblasts.