Histocultures of human prostate tissues for pharmacologic evaluation

This study evaluated the growth of human prostate tumors in histoculture, an in vitro culture technique that maintains three-dimensional tissue structure and organization. Eighty-six percent of 50 tumor specimens from 50 patients were successfully cultured. The histocultures showed proliferation of epithelial tumor cells and stromal cells. Prostate specific antigen (PSA) and prostatic acid phosphatase (PAP) were detectable by immunohistochemistry for at least 8 weeks. Synthesis of PSA was further confirmed by its presence in medium. The mean thymidine labeling index (LI) of the neoplastic cells was 62%. There was no correlation between thymidine LI and tumor grade. The explants maintained their characteristics for at least 8 weeks as indicated by unchanged thymidine LI, PSA and PAP immunohistochemistry after 2 and 8 weeks in culture. A 24 to 48 hour delay in processing the tissues for culture did not reduce the thymidine LI. The thymidine LI and PSA and PAP staining in tumors cultured in a Minimal Essential Medium (MEM)-based or a PFMR-4-based culture medium were similar, suggesting an insignificant effect of the medium on cell proliferation. Migration of neoplastic cells from the tissue fragments into the collagen gel matrix was noted in 1 of 10 samples cultured in MEM-based medium versus 8 of 10 samples cultured in PFMR-4 medium (p < 0.01). Exposure of 13 patient tumors to suramin, doxorubicin and 5-fluorouracil at clinically relevant concentrations and duration showed tumor sensitivity in 23%, 31% and 15% of the specimens. These values approximate the historical clinical response rates. These data suggest that the histoculture system holds promise for short-term culture of human patient prostate tumor specimens for biologic and pharmacologic studies.