An inertial-based spiral device for separating rare tumor cells from liquid biopsies

Early detection of primary tumors and metastatic processes increases the success of anti-tumor therapies and favors good prognoses. Within the current range of methods available to detect the presence of tumors, liquid biopsy is receiving particular attention as it is a minimally invasive and quick procedure. Identification of cancer elements such as circulating tumor cells (CTCs) constitutes valuable information about tumor biology. However, this is a challenging process due to the rarity of those cells in corporal fluids such as blood (CTCs <10 cell/10 mL blood). Microfluidics, an affordable, sensitive, user-friendly and rapidly evolving technology, has significantly provided advances in the detection and isolation of rare cancer cells. One of the main strategies currently employed is the development of inertial focusing devices with spiral geometries. In these systems, hydrodynamic forces are used to focus particles as a function of their size without additional mechanical or electronic equipment. Specifically, the interactions between inertial lift forces and Dean vortices determine the equilibrium position of particles as a function of their size, enhancing their sorting. Here, by combination of viscoelastic and inertial microfluidics approaches, we have developed a spiral device for isolation of CTCs from liquid biopsies. Our device was able to isolate and enrich with high efficiency osteosarcoma cells presented in a low number from whole blood samples. This device constitutes a promising tool for isolation, characterization and potential culture of tumor cells from patient samples and improve personalized medicine.