GROWTH AND CHARACTERIZATION OF PORCINE URINARY-BLADDER EPITHELIAL-CELLS IN-VITRO

Dividing long-term monolayer cultures of porcine urinary bladder epith elial cells were obtained by a combined mechanical and enzymatic isola tion method. The serum-free cultured cells were investigated morpholog ically and characterized according to their growth characteristics and enzymatic functions. Investigations over a period up to 12 wk demonst rated that the cells regain their in vivo polarization with apically s ituated membrane vesicles and tight junctions between neighboring cell s when they have built up a confluent monolayer. Activities of most ma rker enzymes for cell-differentiated status and function of such cells observed over a period of 4 wk in culture were conserved compared wit h the original tissue. Lactate dehydrogenase activity release into the medium was at low levels (less than or equal to 5% of the total amoun t), indicating a good membrane integrity and cell. viability. The chro mosome set (2n = 38) did not change significantly during the first 5 w k, but, with additional culture time, the degree of polyploid and poly nucleated cells increased comparable to the in vivo situation, in whic h the apical cell layer of the bladder mucosa also showed a high degre e of polynucleation and polyploidy, indicative of a senescence process .