Prolonged survival of human spermatozoa when co-incubated with epididymal cell cultures.

Human epididymal tissue was recovered from 11 patients undergoing orchidectomy without anti-androgen treatment. Everted epithelial fragments from the caput and corpus epididymis of six patients were successfully cultured in a modified RPMI 1640 medium supplemented with HEPES and androgens for up to 110 days (mean 56 ± 28) in 5% CO 2 in air at 37°C. Epithelial cells from human oviduct and non-reproductive tract cells (breast epithelial cells, fibroblasts) were also cultured for comparison. The proportion of epididymal epithelial cells in primary cultures assessed by immunofluorescent localization using a cytokeratin monoclonal antibody was shown to be >70% for the first 6-8 weeks of culture. Light and electron microscopy indicated that epithelial cells maintained polarity and some normal morphology during the culture period. Washed epididymal or ejaculated spermatozoa prepared by a 'swim-up' procedure were co-incubated (i) directly with epididymal cells in culture wells, (ii) in 12 mm Millicell® inserts within culture wells, thereby preventing contact of spermatozoa with culture cells; and (iii) in culture medium alone. A significant proportion of spermatozoa in direct contact with culture cells or in Millicell inserts were viable after 6 days of co-incubation (30-45%) and exhibited progressive motility, while all spermatozoa in medium alone were non-motile by 3 days. Using computer-assisted sperm analysis it was shown that the progressive motility of viable spermatozoa decreased gradually for the first 5 days in culture and then remained constant (∼30 μm/s, average path velocity). After 12 days of co-incubation, 15 ± 4% of spermatozoa in direct contact with epithelial cells remained motile; in one experiment, a few spermatozoa (<1%) were motile at 17 days. Light and electron microscope observations indicated that prolonged sperm survival was associated with close apposition of spermatozoa (by equatorial segment) to the apical membrane of epithelial cells. Oviductal epithelial cells were also beneficial for sperm survival, but other cell types had no effect.