Scientists at the University of Toronto (ON, CA) have reported the development of a new microfluidic device that could be used to detect the presence – or monitor the progression – of multiple myeloma (MM), a type of blood cancer.The American Cancer Society (GA, USA) estimates that approximately 27,000 new cases of MM are diagnosed annually, with over 11,000 of these cases resulting in the death of a patient. In MM, malignant plasma cells – a type of white blood cell (WBC) – accumulate in the bone marrow, causing it to fail. In healthy individuals the bone marrow is responsible for the production of red blood cells.
Recent research has demonstrated that malignant cells are capable of leaving the bone marrow and entering the blood stream. The presence of these cells, known as clonal circulating plasma cells (cCPCs), in the blood has been correlated with shorter survival times.
The research, published in Biomicrofluidics, overcomes the limitations of using existing methods to detect low levels of these cells in MM patients by utilizing a microfluidic device platform.
In the flow channel of the newly developed device are micropillars; as blood filters through the device, healthy blood cells pass through these pillars, while cancerous cCPCs are trapped. The device was developed using a computational model to identify the best design from various shapes and sizes of pillars. The team found that diamond-shaped pillars provide a low resistance to flow, and filtering action was improved by making the diamond pillars longer and more pointed.
The microfluidic device functions as a filter due to the size differences of cells. Red blood cells are the smallest cells in blood plasma (diameter 6–8 micrometers), followed by WBCs (diameter 7–30 micrometers), whereas cCPCs are generally larger (diameter 30–50 micrometers). Although the smallest cCPCs are a comparable size to the largest WBCs, WBCs can deform to fit through the pillars; the stiffer cCPCs cannot and therefore become trapped.
The research was performed on cultured cancer cells and blood samples from patients with MM. The quantity of captured cCPCs in samples from patients with active myeloma was much higher than in samples from patients in remission or healthy individuals.
Co-author Lidan You (University of Toronto) explained: “This device shows great potential as a noninvasive method for either early detection or monitoring of MM disease progression.”
Sources: Ouyang D, Li Y, He W et al. Mechanical segregation and capturing of clonal circulating plasma cells in multiple myeloma using micropillar-integrated microfluidic device. Biomicrofluidics. doi:10.1063/1.5112050 (2019)(Epub ahead of print); www.eurekalert.org/pub_releases/2019-11/aiop-tfh111219.php