Immuno-Liposome Nanoparticle Microarray for Detection of Circulating Tumor Cells

Immuno-Liposome Nanoparticle Microarray for Detection of Circulating Tumor Cells

Kwang Joo Kwak^1,2, Bo Yu¹, Yun Wu¹, Xinmei Wang¹, David J. Vanderah³, and L. James Lee^1,2*

 

¹NSF Nanoscale Science and Engineering Center for Affordable Nanoengineering of Polymeric Biomedical Device (NSEC-CANPBD)

²Department of Chemical and Biomolecular Engineering

³Biomolecular Structure and Function Group at the Center for Advanced Research in Biotechnology (CARB), National Institute of Standards and Technology (NIST), Rockville, Maryland 20850

The Ohio State University, Columbus, Ohio 43210

*Contact author- E-mail: lee.31@osu.edu

Using circulating tumor cells (CTCs) in blood as a biomarker for early cancer detection has gained a great deal of attention in the medical field lately because such ‘liquid biopsy' approach is non-invasive and simple. Although a number of devices have been developed for separating and characterizing CTCs [1], including the commercially available and FDA approved CellSearch^TM system (Veridex, Warren, NJ), it is very difficult to produce repeatable quantitative results because of their extreme rarity, i.e. ~5 CTCs among more than 5 billions blood cells in 1 ml blood sample. Recently, a group of researchers at Harvard Medical School developed microfluidic devices, i.e. ‘CTC chip', mediated by the interaction of CTCs and microposts [2] or CTCs and chip surface [3] coated with antibody against epithelial cell adhesion molecule (EpCAM) under controlled laminar-flow conditions [2]. Their approach was able to yield recovery rates of >65% spiked cancer cells in phosphate buffered saline (PBS) at 100 cells ml^-1. Although impressive, this result is still far away from the sensitivity (>90% recovery rate at <10 CTCs ml^-1) required for clinic use.

In ths work, we show a novel immuno-liposome nanoparticles (ILNs) array design with improved sensitivity and specificity of CTCs isolation comparing to the conventional antibody approaches. Recent advances in biomimetic lipid membranes provide opportunities to develop applications such as cellular recognition. Novel tethered bilayer liposome nanoparticles (tBLNs) that can be conjugated on a planar surface through a self-assembled monolayer (SAM) of a thiolipid and modified with EpCAM or therapeutic targeting antibodies are our basic design. The antibody conjugated ILNs with a diameter around 100 nm were tethered onto the chip surface through the post-insertion and/or biotin-avidin linking to form an array with each site around 5-15 µm diameter. The remaining chip surface was covered by PEG to prevent non-specific cell binding. In comparison, a similar array made of the same antibody and PEG coating without any liposome nanoparticles was also prepared. Using the mixture of two cell lines and pre-treated 1 ml human blood sample with ‘spiked' MCF-7 breast cancer cell line as model systems, the experimental results showed that our ILN array performed better than the antibody array and other cell separation methods. Our new approach has potential for many important biomedical applications such as prognosis of cancer patients and monitoring targeted therapy.

References

[1] Budd G. T., Mol. Pharm. 6(5), 1307-1310 (2009).

[2] Nagrath S, et al. Isolation of rare circulating tumor cells in cancer patients by microchip technology. Nature. 450: 1235 (2007).

[3] Stott S., et al. PNAS 107(43), 18392–18397 (2010).