INTERACTIONS BETWEEN ADULT HUMAN PROSTATIC EPITHELIUM AND RAT UROGENITAL SINUS MESENCHYME IN A TISSUE RECOMBINATION MODEL

Tissue recombinants composed of adult human prostatic epithelium (hPrE ) and rat urogenital sinus mesenchyme (rUGM) were grafted beneath the renal capsule of athymic rodent hosts. The pseudostratified human epit helium initially became multilayered, solid epithelial cords emerged, grew into the surrounding mesenchyme and canalized to regenerate a pse udostratified epithelium. Basal cells expressed cytokeratins 5 and 14, while luminal cells expressed cytokeratins 8 and 18, prostate specifi c antigen and prostatic acid phosphatase. The rat mesenchymal componen t differentiated into thick sheets of smooth muscle, characteristic of the human but not the rat prostate. These findings indicate that epit helial-mesenchymal interactions were reciprocal. Rat UGM induced adult hPrE to form new ductal-acinar tissue, involving epithelial prolifera tion, ductal branching morphogenesis and functional cytodifferentiatio n. Concurrently the epithelium dictated smooth muscle differentiation and patterning. Species-specific reverse transcriptase polymerase chai n reaction SC (RT-PCR) analysis of the tissue recombinants was perform ed to separately examine the expression of epidermal growth factor (EG F), transforming growth factor-alpha (TGF-alpha), Epidermal growth fac tor receptor (EGFR), TGF-beta 1, and TGF-beta 3 in the epithelium, str oma and host components of the graft. All of these genes, except TGF-b eta 1, were expressed in all three tissues. Human TGF-beta 1 was not d etected, indicating that this gene was not expressed in human prostati c epithelium but was present in stroma.