Jiang, Strand, Fernandez et al. 347 Figure 1. Reconstruction of benign glandular tissues by primary human prostate epithelial cells NHPrE0 and BHPrE0. A: Phenotypically, pri- mary HPrE cells NHPrE0 and BHPrE0 under phase contrast microscopy are small with some elongated spindle-shaped cells with limited cobble- stone morphology. Scale bar ¼ 100 lm. Hematoxylin and eosin–stained sections of tissue recombinants made using NHPrE0 or BHPrE0 plus rat UGM show well-differentiated glandular formation at 6 months or 4 months after grafting, respectively. The glandular structure is composed of two epithelial layers, luminal and basal. Secretion is found in the lumen of the gland. Scale bar ¼ 100 lm (low magniﬁcation) or 50 lm (high magiﬁcation). B: Immunophenotyping of regenerated human prostatic epithelium plus rat UGM. In the ductal-acinar structure, CK14 protein is expressed in basal cells, whereas CK18 protein is localized in secretory luminal cells. PSA is positive in the luminal cells lining differentiated ducts. All epithelial and some stromal cells show AR immunoreactivity. Vimentin is positive in some periacinar stroma. a-actin identiﬁes the smooth muscle layer. Scale bar ¼ 50 lm. Abbreviations: AR, androgen receptors; BHPrE0, primary cultured benign human prostate epithelial cells isolated from a prostate surgical sample; HPrE, human prostate epithelial cells; NHPrE0 (NHP8), primary cultured ‘‘normal’’ human prostate epithelial cells isolated from a donated, 41-year-old, healthy, male prostate; PSA, prostate-speciﬁc antigen; UGM, urogenital sinus mesenchyme. luminal-type cells [19]. BHPrE0 cells were morphologically similar to the NHPrE0 cells, with more luminal-type cells detected with CK18 IF staining (data not shown). In tissue recombinants, well-differentiated and apparently mature duc- tal-acinar architecture was found. The number of such struc- tures was dependent upon the ratio of implanted epithelial www.StemCells.com