Pleural effusion is very common and involves abnormal deposition of fluid in the pleural space. Malignant pleural effusion is the major cause of exudates in thoracentesis patients. Most cases of malignant pleural effusion are caused by lung cancer, breast cancer, and lymphoma; 15% of lung cancer patients will present with malignant pleural effusion initially, and up to 50% will have malignant pleural effusion throughout the course of the disease. Several techniques can be used for the diagnosis of malignant pleural effusion . Cytomorphology is the clinical gold standard for malignant effusion diagnosis. Nonetheless, cytology has a modest false-negative rate due to analysis, interpretation and collection errors. Morphologically differentiating among reactive mesothelial cells, macrophages, and malignant cells can be challenging, and hypocellular and bloody specimens are particularly difficult. Immunohistochemistry is a common supplemental technique that significantly improves cytological diagnosis and is mostly performed on sections of paraffin-embedded cell blocks. Furthermore, in the age of precision medicine, cancer cells found in effusion may be an important source of malignant cells following cancer relapse or metastasis in the lung, particularly when the primary tumor has been removed. Therefore, differentiating cancer cells within malignant effusion and conducting molecular analyses may be important to determine the cancer''s current mutational status, which is important for selecting a targeted therapy.
Dr. Bor-Ran Li’s group developed a spiral microfluidic device that can rapidly isolate cancer cells and improve their purity through fluid dynamics. This label-free, high-throughput device continuously isolates cancer cells and other unrelated molecules from pleural effusion. Most of the background cells that affect interpretation are flushed to outlets 1 to 3, and cancer cells are hydrodynamically concentrated to outlet 4, with 90% of lung cancer cells flowing to this outlet. After processing, the purity of cancer cells identified in pleural effusion by CD45 and epithelial cell adhesion molecule (EpCAM) antibodies in flow cytometry will be increased by 6 to 24 times. The microfluidic device presented here has the advantages of rapid processing and low cost, which are conducive to rapid and accurate clinical diagnosis.
Among cancer patients, the major reason causing the high mortality is metastasis, which means that cancer cells invade into the blood or lymph system and form new tumor(s). The cancer cells existing in blood, or circulating tumor cells (CTCs), provide abundant information for diagnosis and prognosis. However, the population of CTCs in the whole blood is much lower than that of red blood cells (RBCs), which might interfere the cancer detection. Therefore, we want to develop a device that can reject the blood cells efficiently and enrich the cancer cells rapidly.
Using the same techniques, we designed a cascade spiral microfluidic device (CSMD) and continuously isolated the unlabeled cancer cells from blood sample without lysing processes. The particles with different sizes were focused in different regions of the spiral microchannels due to the inertial lift force and the Dean force. We successfully optimized the system by adjusting the height of the microchannel and the input pressure, and used fluorescent microbeads and cancer cells spiked in whole blood to visualize the result and calculate the focusing and separation efficiency. After the cancer cells were collected, they were analyzed by the immunofluorescence and flow cytometry. The results showed that the CSMD device excluded high percentage of RBCs in the first stage and recollected the cancer cells in the second stage. The CSMD device can efficiently enrich the cancer cells more than 1000 times in 10 minutes, which substantially curtailed sample preparation time and improved the accuracy of diagnosis. In conclusion, this device provides several advantages, such as continuous processing, low-cost, time-saving and no cross-contamination of clinical samples. In view of this, we highly expect that the CSMD device will be a crucial improvement in the field of cancer diagnosis in the near future.
Sample processing workflow with the spiral microfluidic channels.
Dr. Bor-Ran Li’s group was awarded by 16th National Innovators.