Circulating tumor cell isolation, culture, and downstream molecular analysis

Abstract

Circulating tumor cells (CTCs) are a major contributor of cancer metastases and hold a promising prognostic significance in cancer detection. Performing functional and molecular characterization of CTCs provides an in-depth knowledge about this lethal disease. Researchers are making efforts to design devices and develop assays for enumeration of CTCs with a high capture and detection efficiency from whole blood of cancer patients. The existing and on-going research on CTC isolation methods has revealed cell characteristics which are helpful in cancer monitoring and designing of targeted cancer treatments. In this review paper, a brief summary of existing CTC isolation methods is presented. We also discuss methods of detaching CTC from functionalized surfaces (functional assays/devices) and their further use for ex-vivo culturing that aid in studies regarding molecular properties that encourage metastatic seeding. In the clinical applications section, we discuss a number of cases that CTCs can play a key role for monitoring metastases, drug treatment response, and heterogeneity profiling regarding biomarkers and gene expression studies that bring treatment design further towards personalized medicine.

Examination of the dielectrophoretic spectra of MCF7 breast cancer cells and leukocytes

“…Processing and analyzing CTCs are still challenging as they are in significantly low concentrations, approximately 1–100 CTCs per 1 mL blood . Most of the techniques developed to analyze CTCs have some form of enrichment method by isolating CTCs and/or removing blood cells to make the number of cells manageable.…”

“…Although density gradient centrifugation is cost effective, CTC loss is possible due to the unwanted migration of CTCs into the plasma . Size/deformability‐based techniques allow enrichment of CTCs in a time‐efficient manner; however, they fail to enrich CTCs that have similar size and/or deformability with blood cells, especially with leukocytes . Membrane clogging, cluster formation, and the problems related to the release of the collected CTCs from the membranes for downstream analyses are the main drawbacks of these systems .…”

Beyond Capture: Circulating Tumor Cell Release and Single‐Cell Analysis

“…According to the latest estimates on the global burden of cancer, there will be 9.6 million cancer deaths in 2018, and cancer has become the second leading cause of death in countries of all income levels . Over 90% of cancer‐related mortalities are attributed to tumor metastasis . The metastatic process occurs via tumor cells shedding from solid tumor tissues, which can circulate in lymphatic system or vasculature and potentially invade and colonize distal sites .…”

“…Over 90% of cancer‐related mortalities are attributed to tumor metastasis . The metastatic process occurs via tumor cells shedding from solid tumor tissues, which can circulate in lymphatic system or vasculature and potentially invade and colonize distal sites . These tumor cells, known as circulating tumor cells (CTCs), are believed to account for the hematogenous spread and metastasis of cancers .…”

Identification and Single‐Cell Analysis of Viable Circulating Tumor Cells by a Mitochondrion‐Specific AIE Bioprobe

“…Of the 22 patients with liver cancer, 11 (50%) had detectable CTCs ranging from 1 to 8 per 5 mL of whole blood (1.2 ± 1.9 CTCs). As CTCs were enriched by the size‐based ClearCell FX system, the lower detection rate in blood of liver cancer may be due to the relatively smaller size of liver CTCs . In the healthy donors group, only 1 out of 12 volunteers has 2 putative cells, which is significantly lower than the cancer patients groups.…”