Abstract:Objective To investigate the viability of the protocol to sort tumor cells from ovarian cancer peritoneal fluids by combining immunocytochemistry (ICC) and fluorescence in situ hybridization (FISH). Methods The ovarian cancer peritoneal fluid model was established and divided into a negative control group and four positive groups by adding 0, 5, 10, 20 and 40 ovarian cancers SKOV3 cells marked by Mito-Tracker Green into 4 ml benign peritoneal washing fluid respectively, 3 duplications per group. The nude mouse model bearing orthotopically transplanted human ovarian cancer SKOV3 cells was established, including the negative control group and the positive group, with 6 BALB/c nude mice per group and 2 nude mice at each time point. Peritoneal fluids of the nude mice in the positive group were collected at the 4th, 6th and 8th w after transplanting SKOV3 cells under the capsule of the left ovary. SKOV3 cells were enriched from the peritoneal fluids by magnetic activated cell sorting (MACS). Then, the cancer cells were identified exactly by EBA-1-ICC and CEP8-FISH (Chromosome Enumeration Probe). The cells with the characteristic of DAPI+/EBA-1+/Mito-Tracker Green+/CEP8+ were classified as detected cancer cells by the positive standard of CEP8 >2. Results In the peritoneal fluid model, the EBA-1-positive cells were found in the negative control group and all SKOV3 cell-positive groups, the marked SKOV3 cells were found in all SKOV3 cell-positive groups and their recovery rates were 20%-50%, the detection rates in 9 of 12 SKOV3 cell-positive samples were 100%. In the nude mouse model, under every 20×10 microscopic field, the maximum number of SKOV3 cancer cells was 3, 8 and 15 respectively at the 4th, 6th and 8th w. Conclusions The protocol of combining ICC and FISH can exactly identify cancer cells from ovarian cancer peritoneal fluids which have been enriched by MACS. The technique provides new ideas for studying ovarian cancers.