Isolation and detection of circulating tumour cells from metastatic melanoma patients using a slanted spiral microfluidic device

// Carlos A. Aya-Bonilla 1 , Gabriela Marsavela 1 , James B. Freeman 1 , Chris Lomma 2 , Markus H. Frank 1, 3, 4 , Muhammad A. Khattak 5, 6 , Tarek M. Meniawy 6, 7 , Michael Millward 6, 7 , Majid E. Warkiani 8 , Elin S. Gray 1 and Mel Ziman 1, 9 1 School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia 2 Department of Health, Perth, Western Australia, Australia 3 Transplantation Research Program, Boston Children’s Hospital and Department of Dermatology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA 4 Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts, USA 5 Department of Medical Oncology, Fiona Stanley Hospital, Murdoch, Western Australia, Australia 6 School of Medicine and Pharmacology, University of Western Australia, Crawley, Western Australia, Australia 7 Department of Medical Oncology, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia 8 School of Mechanical and Manufacturing Engineering, Australian Center for NanoMedicine, University of New South Wales, Sydney, New South Wales, Australia 9 School of Pathology and Laboratory Medicine, University of Western Australia, Crawley, Western Australia, Australia Correspondence to: Carlos A. Aya-Bonilla, email: c.ayabonilla@ecu.edu.au Keywords: circulating tumour cells (CTCs), metastatic melanoma, slanted spiral microfluidics Received: March 10, 2017 Accepted: May 22, 2017 Published: June 27, 2017 ABSTRACT Circulating Tumour Cells (CTCs) are promising cancer biomarkers. Several methods have been developed to isolate CTCs from blood samples. However, the isolation of melanoma CTCs is very challenging as a result of their extraordinary heterogeneity, which has hindered their biological and clinical study. Thus, methods that isolate CTCs based on their physical properties, rather than surface marker expression, such as microfluidic devices, are greatly needed in melanoma. Here, we assessed the ability of the slanted spiral microfluidic device to isolate melanoma CTCs via label-free enrichment. We demonstrated that this device yields recovery rates of spiked melanoma cells of over 80% and 55%, after one or two rounds of enrichment, respectively. Concurrently, a two to three log reduction of white blood cells was achieved with one or two rounds of enrichment, respectively. We characterised the isolated CTCs using multimarker flow cytometry, immunocytochemistry and gene expression. The results demonstrated that CTCs from metastatic melanoma patients were highly heterogeneous and commonly expressed stem-like markers such as PAX3 and ABCB5. The implementation of the slanted microfluidic device for melanoma CTC isolation enables further understanding of the biology of melanoma metastasis for biomarker development and to inform future treatment approaches.