Characterization of a stromal cell model of the human benign and malignantprostate from explant culture

Purpose: There is a lack of suitable in vitro models for the human prostate . To study stromal-epithelial interactions, we established stromal cells in cultures from benign and malignant prostate tissue that resemble more clos ely the in vivo conditions of the human prostate. Materials and Methods: Stromal cells were obtained from explant primary cul ture, established in DU145 cell conditioned medium and maintained in RPMI-f etal bovine serum (FBS) supplemented with insulin, transferrin and selenium (ITS), Proliferation studies to compare different media were performed usi ng a (3)[H]thymidine assay. Stromal cells were characterized by immunocytoc hemistry using epithelial and mesenchymal markers. Morphology was evaluated by electron microscopy, light and phase-contrast microscopy. Androgen rece ptor (AR) mRNA expression was measured by polymerase-chain-reaction (PCR). The response to different concentrations of dihydrotestosterone (DHT) and t he antihormones flutamide and hydroxyflutamide was tested by 3[H] thymidine assay. Results: Microscopic evaluation revealed typical stromal morphology with el ongated cell shapes, cilia, collagen and microfilaments. Immunocytochemical characterization revealed typical fibroblastic and smooth muscle different iation. ITS supplemented in RPMI-FBS showed the best growth stimulation com pared with other serum-free media (p < 0.05) and became our basal medium, T he presence of DU145 cell conditioned medium in this basal medium showed a significant increase in cell proliferation in stromal cells. Stromal cells maintained AR mRNA expression and significant DHT dose dependent growth sti mulation in up to 10 passages. Both the antiandrogens flutamide and hydroxy flutamide counteracted the DHT effect (p < 0.05). Conclusions: This stromal cell model maintains many cellular and functional properties of the human prostate, which may enable us to study growth fact or modulation, drug and hormone metabolism in stromal-epithelial interactio n with emphasis on the pathogenesis of BPH and prostate cancer.