Circulating Tumor Cells (CTCs) have been linked to cancer progression, but are difficult to isolate, as they are very rare and heterogeneous, covering a range of sizes and expressing different molecular receptors. Filtration has emerged as a simple and powerful method to enrich CTCs, but only captures cells above a certain size regardless of molecular characteristics. Here, we introduce antibody-functionalized microfilters to isolate CTCs based on both size and surface receptor expression. We present a 3D printed filtration cartridge with microfabricated polymer filters with 8, 10, 12, 15 or 20 µm-diameter pores. Pristine filters were used to optimize sample dilution, rinsing protocol, flow rate and pore size, leading to > 80 % for the recovery of spiked cancer cells with very low white blood cell contamination (< 1000). Then, filters were functionalized with antibodies against either epithelial cell adhesion molecule (EpCAM) or epidermal growth factor receptor (EGFR) and the cartridges were used to enrich breast (MDA-MB-231, MCF-7) and renal (786-O, A-498) cancer cells expressing various levels of EpCAM and EGFR. Cancer cells were spiked into human blood, and when using filters with antibodies specific to a molecular receptor expressed on a cell, efficiency was increased to > 96 %. These results suggest that filtration can be optimized to target specific CTC characteristics such as size and receptor expression, and that a diverse range of CTCs may be captured using particular combinations of pore size, filtration parameters, and antibody functionalization.
Analytical chemistry. 2016 Jul 21 [Epub ahead of print]
Anne Meunier, Javier Alejandro Hernández-Castro, Kate Turner, Kebin Li, Teodor Veres, David Juncker