A novel technique for the enrichment of primary ovarian cancer cells

Primary cancer cells that are extracted from ovarian tumors can serve as an optimal substrate to study the biologic characteristics of ovarian cancer. We describe an efficient and effective method of enriching ovarian tumor cells from ascitic fluid using an immunomagnetic-based method.

Mononuclear cells were isolated from ascites specimens by Ficoll gradient separation. Epithelial ovarian cancer cells were labeled magnetically with monoclonal human epithelial antigen-125 that is conjugated to microbeads. After immunomagnetic separation, the purity of tumor cells before and after purification was quantified by cytologic analysis and confirmed by fluorescence-activated cell sorter analysis.

Peritoneal ascites specimens were obtained from 6 patients with ovarian cancer. The median age of our patients was 61.5 years (range, 46-79 years). Three patients had papillary serous carcinoma; 2 patients had clear cell carcinoma, and 1 patient had an undifferentiated adenocarcinoma. The mean tumor purity was only 22.8% +/- 10% (range, 1%-60%) before separation. After enrichment, the purity improved to 82.3% +/- 4.0% (range, 70%-90%). Our enrichment technique increased the tumor purity by 59.5% +/- 8.4%. The mean percent yield after positive enrichment was 30.1% +/- 14.5%.

The immunomagnetic cell separation technique is an efficient and effective method for isolating and purifying ovarian tumor cells from ascites. Results from experiments with fresh tumor cells rather than cancer cell lines may be more relevant for clinical application.