A microfluidic chip incorporating magnetic sorting and invasive separation for isolation, culture and telomerase analysis of circulating tumor cells

Circulating tumor cells (CTCs) are a crucial indicator of cancer metastasis, and are vital for early diagnosis, disease monitoring, and treatment response evaluation. However, their extremely low concentration and the complexities of isolation techniques pose a significant challenge in capturing and analyzing CTCs. In this study, we developed a novel microfluidic system that integrates magnetic capture and invasive screening onto a single microfluidic chip. By attaching positively charged magnetic nanoparticles to negatively charged CTCs, the magnetic separation of CTCs within the chip effectively eliminates interference from blood cells. A total of 2 mL blood sample can be processed within 3 min, achieving an impressive tumor capture efficiency of 84 %. Using the chip, we also successfully achieved long-term culture of CTCs, and identified CTCs with high activity and invasive potential in blood samples from 11 patients with colorectal cancer. Finally, we analyzed telomerase activity in cultured CTCs on the microfluidic chip. Significantly higher invasive potential and telomerase activity were observed in CTCs from the malignant tumor group compared to the benign group (P < 0.01), highlighting their increased aggressiveness. This study offers a novel approach for efficient CTCs isolation, culture, and telomerase analysis, clarifying the crucial role of telomerase in tumor metastasis and providing profound insights for future research on telomerase-targeted tumor metastasis.