Using a combination of gangliosides and cell surface vimentin as surface biomarkers for isolating osteosarcoma cells in microfluidic devices

BACKGROUND: Osteosarcoma (OS) is the most common primary bone tumor and the third leading cause of pediatric cancer deaths. Liquid biopsies are an alternative to current diagnostic imaging modalities that can be used to monitor treatment efficacy and the development of metastases. This study addresses the use of novel biomarkers to detect circulating osteosarcoma cells. PROCEDURES: Flow cytometry was used to evaluate the relative expression of epithelial cell adhesion molecule (EpCAM), ganglioside 2 and 3 (GD2/3), and cell surface vimentin (CSV) on a panel of OS cell lines. A microfluidic device was used to affirm the efficacy of GD2/3 and CSV to capture CTCs. Once captured, CTCs on the device are enumerated and the capture efficiency for each marker is measured. Patient samples were captured using the LFAM chip. RESULTS: We report the evaluation of GD2, GD3, and CSV as markers for OS cell capture in cell lines and in patient samples. The results of our capture studies correlate with our flow cytometry data and have shown a low capture efficiency of OS cells using EpCAM antibodies, while showing a moderate capture efficiency of OS cells using the GD2, GD3, and CSV antibodies independently. The combination of biomarkers demonstrate a high capture efficiency of approximately 80%. This is further supported by the detection of 1–1.5 CTCs per mL of blood using GD2 + CSV in OS patient samples. CONCLUSIONS: The combination of GD2 + CSV significantly increased the capture efficacy of OS cells. The detection of CTCs through routine blood sampling may be used clinically for earlier detection of metastases and monitoring the therapeutic effect of treatments in metastatic osteosarcomas.