<i>In Vivo</i> Capture of Circulating Tumor Cells Based on Transfusion with a Vein Indwelling Needle

Detection of circulating tumor cells (CTCs) could be used as a “liquid biopsy” for tracking the spread of cancer. <i>In vitro</i> detection methods based on blood sampling and <i>in vitro</i> CTC capture often suffer from the small sampling volume and sampling error. Here, the <i>in vivo</i> capture of CTCs based on transfusion with a surface-modified vein indwelling needle is proposed. When the needle was applied to transfusion in the vein, the simultaneous capture of CTCs was performed. To investigate the actual capture efficiency of the <i>in vivo</i> capture method, labeled MCF-7 cells were directly injected into the veins of rabbits, wild type mice, and nude mice and could be successfully captured. Two of 5 MCF-7 cells injected into the veins of nude mice were successfully captured. To investigate the CTC capture of mouse tumor model and compare with the <i>in vitro</i> method, mice were subcutaneous inoculated with metastatic 4T1 cells. Seven and 21 days after inoculation, CTCs were captured for the first time using <i>in vivo</i> and <i>in vitro</i> methods, respectively. This predicted that the <i>in vivo</i> method could be more suitable for use of early diagnosis of cancer than the <i>in vitro</i> method. As CTC capture can be performed at the same time as transfusion and does not cause further bodily harm, it would be easily accepted by patients. This efficient, simple, and less damaging method involving the use of a vein indwelling needle could be popularized easily in the clinic.