Abstract
Circulating tumor cells (CTCs) are exfoliated at various stages of cancer, and could provide invaluable information for the diagnosis and prognosis of cancers. There is an urgent need for the development of cost-efficient and scalable technologies for rare CTC enrichment from blood. Here we report a novel method for isolation of rare tumor cells from excess of blood cells using gas-filled buoyant immuno-microbubbles (MBs). MBs were prepared by emulsification of perfluorocarbon gas in phospholipids and decorated with anti-epithelial cell adhesion molecule (EpCAM) antibody. EpCAM-targeted MBs efficiently (85%) and rapidly (within 15 minutes) bound to various epithelial tumor cells suspended in cell medium. EpCAM-targeted MBs efficiently (88%) isolated frequent tumor cells that were spiked at 100,000 cells/ml into plasma-depleted blood. Anti-EpCAM MBs efficiently (>77%) isolated rare mouse breast 4T1, human prostate PC-3 and pancreatic cancer BxPC-3 cells spiked into 1, 3 and 7 ml (respectively) of plasma-depleted blood. Using EpCAM targeted MBs CTCs from metastatic cancer patients were isolated, suggesting that this technique could be developed into a valuable clinical tool for isolation, enumeration and analysis of rare cells.
Highlights
As cancer progresses, malignant cells are shed into the blood [1,2,3]
Besides counting Circulating tumor cells (CTCs) numbers of as a prognostic marker, genetic profiling and expression analysis of CTCs are a promising approach for cancer prognosis and drug screening [33]
Using epithelial cell adhesion molecule (EpCAM) targeted MBs we achieved 88% isolation efficiency of tumor cells spiked at high concentration (100,000 cells/ml) in 1 ml of plasma-depleted blood, and 77% isolation efficiency of rare cells (23 cells/ml) spiked in 7 ml of plasma-depleted blood
Summary
Malignant cells are shed into the blood [1,2,3]. Circulating tumor cells (CTCs) could provide invaluable information for the monitoring of tumor progression and recurrence in cancer patients [1,2,3]. The most common strategy for isolating CTCs from blood is based on the use of immunomagnetic beads coated with anti-epithelial EpCAM [4,5,6,7,8], the most commonly used marker for detecting circulating tumor cells [7,9]. An immunomagnetic bead-based CellSearch Assay (Veridex) has received U.S Food and Drug Administration approval for the detection of epithelial CTCs in metastatic cancer patients. At present, this assay is the gold standard for CTC isolation. The field of CTC isolation witnessed a surge of technologies, including microfluidics and filtration. There is a continuing interest in development and testing of cost-efficient, scalable and simple technologies for CTC isolation
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