Body cavity fluid can induce epithelial and mesothelial differentiation from CD34 positive peripheral blood stem cells in vitro.

ABSTRACT

OBJECTIVE: Primary culture of CD34 positive stem cells collected from human peripheral blood was performed with and without supplementation with concentrated ascitic fluid; morphological and immunocytochemical pictures of cultured cells were taken chronologically and compared. METHODS: CD34-positive stem cells collected from peripheral blood were cultured for 1, 24 and 48 hours. Concentrated ascitic fluid was added to the plates for the 24-and 48-hour cultures. For immunocytochemical studies, CD34, AE1/AE3, Ber-Ep4 (EA), EMA, EGFR, CD31, CA125 and D2-40 monoclonal antibodies were used. RESULTS: After culture, small round cells with naked nuclei began to enlarge and to exhibit various changes in the cytoplasm and nucleus. Supplementation with concentrated body cavity fluid enhanced these changes. CD34-positive cells with small round cell features were detected 1 hour after culture and these had no epithelial or mesothelial markers. After 24 hours, CD34-positive cells had disappeared and cells weakly positive for EGFR, EMA, CA125 and D2-40 were detected. Cells with strong and moderate positive reactions for EGFR, AE1/AE3, EA, EMA, D2-40 and CA125 were detected after 48 hours. Supplementation with concentrated body cavity fluid increased the intensity and number of positive cells for these markers compared with the control group. The positive reaction, not only for the epithelial markers such as EGFR and AE1/AE3, but also for mesothelial markers such as CA125 and D2-40, was found to be increased in small numbers of cells in direct proportion to the duration of the primary culture of the peripheral blood cells. CD31, characteristically expressed in endothelial cells, was negative in the cultured cells. CONCLUSION: Supplementation of peripheral blood CD34-positive stem cells with body cavity fluid in vitro enhanced their differentiation toward cells of an epithelial or mesothelial phenotype, concomitant with loss of immunoreactivity for CD34. It is assumed that the routine cytological observation of cells obtained from body cavity fluid might cause possible cytomorphological and immunophenotypical changes due to the action of the growth factors contained in the body cavity fluid.