Evaluation of Isolation Methods for Circulating Tumor Cells (CTCs).

BACKGROUND Detection of CTCs is a poor prognostic factor for many cancer types; however, their very low frequency represents an obstacle for their detection. The objective of the current study was to compare the performance of commonly used methods for CTCs isolation. METHODS The evaluated methods using spiking experiments of MCF7, SKBR3 and MDA MB-231 breast cancer cell lines were (i) ficoll density gradient separation (DGS), (ii) red blood cell lysis (Erythrolysis) isolation, (iii) positive immunomagnetic selection (EpCAM Dynal beads), (iv) two different negative immunomagnetic separation systems (Dynal vs Miltenyi CD45 beads) as well as (v) the Cell Search platform and (vi) the ISET system. RESULTS The recovery rates of Erythrolysis and DGS were 39% and 24%, respectively. Magnetic isolations are ranked from the worse to the best recovery rate as follows:, Myltenyi-anti-CD45 microbeads (24%); Dynal-anti-EpCAM beads (75%); Dynabeads-anti-CD45 (97%). CTCs isolation from blood samples using the CellSearch and ISET systems revealed that the recovery rate for Cell Search and ISET was 52% and 95%, respectively. CONCLUSIONS Dynal-anti-CD45 beads have the best recovery rate compared to other magnetic methods. Furthermore the recovery rate of ISET was higher compared to Cell Search, especially for the more aggressive MDA-MB 231 cell line.