HUMAN PROSTATIC SMOOTH-MUSCLE CELLS IN CULTURE - ESTRADIOL ENHANCES EXPRESSION OF SMOOTH-MUSCLE CELL-SPECIFIC MARKERS

Smooth muscle cells (SMCs) constitute a major cellular component of pr ostatic stroma. SMC tension plays an important role in urethral obstru ction secondary to benign prostatic hyperplasia (BPH). We have develop ed an in vitro procedure for the propagation of human prostatic SMCs. Tissue specimens from patients undergoing radical prostatectomy or cys tectomy were enzymatically disaggregated and cultured in MCDB-131 medi um supplemented with horse serum, insulin, conditioned medium from the tumor cell line CRL-5813, and steroid hormones. The medium was assemb led on the basis of the effects these supplements have on the growth o f SMC cultures and on the expression of the two markers desmin and smo oth muscle myosin. Addition of 0.1 mu M of estradiol to the growth med ium dramatically increased expression of these SMC-specific markers. D ihydrotestosterone (DHT) and hydrocortisone had a similar, albeit less pronounced effect. At three to five passages, about two thirds of the cells were immunohistologically positive for smooth muscle myosin or desmin. Almost all cells were positive for the myofibroblast marker sm ooth muscle a-actin throughout 10 passages and more. In SMC cultures, cells staining for smooth muscle myosin and desmin were found to seek direct contact to myofibroblasts. They grew in aggregates on a layer o f myofibroblasts which adhered to the surface of the culture vessel. A s revealed by transmission electron microscopy the cultured cells exhi bited morphological features of myofibroblasts. Characteristics of smo oth muscle cells, such as prominent bundles of microfilaments associat ed with dense bodies, basal laminae investing the cells, and numerous caveolae at the cell surfaces were regularly observed in cultures of l ow passages. After several passages, these features were markedly decr eased and organelles of the biosynthetic system became more prominent. In summary, we present an in vitro model of prostatic SMCs and demons trate that steroid hormones have characteristic effects on these cells . SMC cultures are expected to facilitate investigation of the functio ns and properties of human prostatic SMCs. (C) 1997 Wiley-Liss, Inc.