Enhanced and High-Purity Enrichment of Circulating Tumor Cells Based on Immunomagnetic Nanospheres

Enrichment and purification of circulating tumor cells (CTCs) from peripheral blood is very critical for their detection and downstream analyses, in which many technologies have achieved good effects. However, efficient and high-purity enrichment of CTCs is still challenging because of their rarity and heterogeneity. Herein, anti-CD45 antibody-modified immunomagnetic nanospheres (IMNs (CD45)) and anti-EpCAM antibody and anti-EGFR antibody cocktail modified IMNs (IMNs (EpCAM & EGFR)) were employed to address the two challenges. The cocktail of anti-EpCAM antibody and anti-EGFR antibody enables capture of tumor cells more efficiently than a single antibody, offsetting the loss of CTCs with EpCAM-negative expression or undergoing epithelial to mesenchymal transition (EMT) potentially. Notably, using IMNs (CD45) to remove the vast majority of white blood cells (WBCs) and IMNs (EpCAM & EGFR) to capture tumor cells successively, our method exhibits excellent enrichment and purification capacity. The purity of the enriched tumor cells can reach 97.6% in mixed-cell samples, while only 57.3% and 35.5% by IMNs (CD45)-based isolation and IMNs (EpCAM & EGFR)-based isolation, and all the enrichment efficiencies reach about 90% by these three methods. Moreover, the rare tumor cells achieve up to 4368-fold enrichment in whole blood samples. Additionally, (90.6 ± 0.9)% of the enriched tumor cells keep viability and can be recultured without a release step. Furthermore, the CTCs are detected successfully in 12 blood samples from cancer patients coupled with immunocytochemistry (ICC) identification. Therefore, by our strategy, the CTCs can be efficiently enriched with high-purity, which is helpful for downstream analyses in cancer diagnoses and personalized treatments.