Nanoscreening Microchip for Circulating Cancer Biomarkers Analysis

Sponsored by: NIH 1R01CA139070-01A2: Detection of Carcinomas, Contract from UT Southwestern Medical Center at Dallas, and Friends Foundation for an Earlier Breast Cancer Test.

Detection of Circulating Tumor Cells (CTCs) in patient blood has been focused on as a strong potential diagnostic tool for early cancer detection. Immunomagnetic separation is among the successful methods employed. Recent development in microsystems has also allowed for capture of these rare cells. We describe a microfluidic chip-based immunomagnetic detection of CTCs. Throughput can be improved through the combination of the well-practiced immunomagnetic separation techniques and optimized engineered design of the microfluidic device. Figures show an illustration of our CTC capture system. CTCs in the blood are labeled with gold-shell magnetic nanoparticles, functionalized with anti-EpCAM antibodies through thiol interactions. As the blood sample is pumped through the microchip, particles as well as labeled CTCs are collected by a permanent magnet allocated below the microfluidic chip. Captured magnetic particles can be seen in the photograph. Samples for preliminary experimentation consisted of either PBS or whole blood spiked with cultured SKBr3 (breast cancer cell) or PC3 (prostate cancer cell). Capture rates of up to 90% and 86% were demonstrated with PBS and whole blood, respectively.

Along this research direction on integrating microfluidics and imaging, we are also developing a rapid method for screening live cells and embryos for mutations and drugs that disrupt molecular pathways essential for cell growth, division and differentiation. To isolate and map genetic signaling pathways, we designed a bio-compatible silicon electronic microfluidic device that automatically positions live embryos within a fluid-filled imaging channel and exposes embryos to differing drug concentrations and constant or biphasic temperature.  This microfluidic “cell assembly line” technology is an extension of our earlier work on an open-substrate system designed to sort, position and rotate cells.  Our lab has demonstrated that a thermal gradient applied across live Drosophila embryos dramatically disrupts primary epithelial cell formation. This process depends on microRNA-mediated translational control, cytoplasmic ribonucleoprotein body function, polarized membrane secretion and cytoskeletal dynamics.  Our ability to rapidly screen genetic mutations and drugs for primary effects on early embryonic morphogenesis in live animals using this advanced microfluidic device should help identify new genetic and pharmacological reagents that can be used to enhance our understanding of the evolutionarily conserved molecular mechanisms that control cell growth, division and differentiation in animals.