Characteristics of nonmalignant and malignant human prostate in organ culture

Prostate tissue was obtained from 52 radical prostatectomies immediately up on surgery. From each specimen, a small piece of tissue was fixed in 10% bu ffered formalin and used for histology, cytokeratin staining, staining with the antibodies to the proliferation-associated antigen (Ki-67), and histoc hemical evaluation of the epithelial-stromal basement membrane. A second pi ece was used for the isolation of epithelial cells and stromal cells in mon olayer culture. The remainder of each specimen was cut into cubes (approxim ately 1 mm on a side) and incubated in organ culture for up to 20 days. At the end of the incubation period, tissue was fixed in 10% buffered formalin and examined as described above with zero-time tissue. These studies showe d that normal epithelial and stromal elements survived in organ culture in the presence of a serum-free medium containing a mixture of growth factors (epidermal growth factor, insulin, pituitary extract, and dihydrotestostero ne). in many of the tissues examined at 4 days, individual glands resembled those seen immediately after surgery, with a single layer of basal epithel ial cells and a layer of secretory cells above. By Day 8, the secretory epi thelium was lost in many places and basal cells proliferated to fill in the lumens of the glands. All of the nonmalignant glands were reactive with th e anti-cytokeratin antibody (K903), and there was a large increase in the n umber of cells staining for Ki-67 as compared with zero-time tissue. Staini ng with the Periodic Acid Schiff (PAS) and PAS-methenamine silver (PASME) r eagents revealed an intact basement membrane around virtually all of the ep ithelial structures. The basement membrane appeared to be thickened in some areas. In places where a gland was cut during the processing of the tissue , epithelial cells migrated out of the gland and covered the cut surface of the tissue piece. There was no detectable basement membrane separating the epithelium from the stroma at these sites. Whereas nonmalignant epithelial cells were preserved in the growth factor- and dihydrotestosterone-supplem ented culture medium, most of the malignant cells rapidly lysed under the s ame conditions. However, when phorbol myristate acetate was included in the culture medium, many of the tumor cells remained viable. This was seen wit h the more well-differentiated tumors as well as with tumors that were high ly anaplastic. All of the tumor cells were nonreactive with anti-cytokerati n antibody, and only a few cells stained for Ki-67. The basement membrane s urrounding malignant cells was thin and, in places, appeared to be disconti nuous. Where malignant glands were cut in the processing of the tissue, cel ls did not migrate out over the cut surface. in summary, this study identif ies culture conditions for the successful maintenance of human prostate tis sue for several days in organ culture. Histological/histochemical features that distinguish nonmalignant and malignant tissue are present in this mode l.