An optically induced electro-kinetics (OEK) chip can separate live gastric cancer cells from ascites and peritoneal lavages, aiding in the early detection of peritoneal metastasis.
Gastric cancer is the third most common cause of cancer death worldwide, accounting for over one million new cases and nearly 800,000 deaths annually. The poor prognosis of gastric cancer can be largely attributed to the difficulty of early diagnosis of peritoneal metastasis, whose presence indicates that the disease has progressed to an advanced stage.
Traditional detection methods struggle to separate and characterize cancer cells in patients’ peritoneal lavages. Distinguishing between cancer and peritoneal mesothelial cells is particularly difficult as both are epithelial in origin and share similar characteristics. Identifying the low concentration of cancer cells in lavages is also difficult, resulting in a lack of sensitivity in a detection method that cannot satisfy clinical demand.
In a study published in Science Advances on 5th August 2020, described a novel optically induced electro-kinetics (OEK) microfluidic method for the diagnosis of peritoneal metastasis using a microfluidic chip. The study was jointly carried out by researchers from the Shenyang Institute of Automation (SIA) of the Chinese Academy of Science (CAS) and City University of Hong Kong (CityU), in cooperation with doctors from the First Hospital of China Medical University.
The researchers successfully separated cancer cells from a simulated peritoneal lavage mixture of gastric cancer cell lines and peritoneal lavage cells in a ratio of up to one to 1000, demonstrating improved sensitivity compared to traditional methods. In addition, they were also able to separate and identify gastric cancer cells with purity up to 71 percent from ascites samples of six patients with different treatment histories.
The OEK chip utilised the significant difference between the size and cell membrane capacitances of gastric cancer and peritoneal lavage cells to detect and separate them. The separation was verified with cytological examination of the separated cells.
This study is first time that OEK has been successfully applied to the separation of clinical gastric cancer ascites samples. In addition to improved sensitivity, OEK has the advantages of being label-free, non-destructive, and fast—gastric cancer cells could be separated and obtained from the microfluidic chip in five minutes. Furthermore, the cells’ (both gastric cancer and peritoneal lavage cells) electrical properties have been proposed as a potential biomarker for multi-dimensional cell profiling.
The direct separation of living cancer cells from clinical samples is of great significance to clinical medicine. The researchers proposed that in the future, separated live cancer cells could be further cultured and used to study the mechanism of peritoneal metastasis. Considering these factors, OEK looks to be a promising system for future clinical use.