Microfluidics and cancer: are we there yet?

Microfluidics and cancer: are we there yet? [Biomed Microdevices. 2013] - PubMed - NCBI

A review by Sunitha Nagrath on the applications of Microfluidic technology to cancer biology and cancer diagnostics, including, CTC isolation, molecular diagnosis, tumor biology and high throughput screening

Isolation and retrieval of circulating tumor cells using centrifugal forces : Scientific Reports : Nature Publishing Group

Isolation and retrieval of circulating tumor cells using centrifugal forces : Scientific Reports : Nature Publishing Group

This paper is from Clearbridge Biomedics, manufacturers of a commercial CTC system (CTC chip), which    is used to isolate CTCs based on physical properties (size and deformability)

The present paper uses inertial microfluidics (explained here and here ), which uses a spiral channel and the centrifugal forces generated within the channel to separate cells based on their physical properties.

http://www.nature.com/srep/2013/130212/srep01259/carousel/srep01259-f1.jpg

Performance Summary:
> 85% recovery
> positive CTCs enumeration in all samples from patients with metastatic lung cancer (n = 20; 5–88 CTCs per mL
> throughput: 3ml/hr.

Commentary:
This work is concurrently ongoing at Clearbridge and University of Cincinnati (now seemingly independently, though the source of origin is university of cincinnati). Prof. Ian Papautsky from the University of Cincinnati has pioneered inertial microfluidics-based cell sorting for a number of years, leading to many publications.

Roche Backing Liquid Biopsy's Development of New CTC Detection Method | GenomeWeb Daily News

Roche Backing Liquid Biopsy's Development of New CTC Detection Method | GenomeWeb Daily News | Clinical Genomics | GenomeWeb

Liquid Biopsy is the CTC lab service offered by Cynvenio biosystems

Cynvenio's core technology can be found here
http://www.cynvenio.com/storage/technical-library/AGBT_2012_Poster_AP_Final_10FEB12.pdf

the working principle behind the isolation system is similar to the ones described here
http://pubs.rsc.org/en/content/articlelanding/2011/lc/c1lc20270g
http://link.springer.com/article/10.1007%2Fs10544-012-9718-8

An Automated High-Throughput Counting Method for Screening Circulating Tumor Cells in Peripheral Blood - Analytical Chemistry (ACS Publications)

An Automated High-Throughput Counting Method for Screening Circulating Tumor Cells in Peripheral Blood - Analytical Chemistry (ACS Publications)

Summary:
This is a very unique paper that presents direct labelling of cells in whole blood. besides the traditional EpCAM, CD4-, CK markers, the authors also used CD44+ marker for stemness.

methods:
1 ml of blood directly stained with markers, centrifuged to remove excess labelling antibody and resuspended and flown through the microfluidic chip. A custom built line-confocal imaging system captures images of cells flowing past the microfluidic channel.
authors had previously published a variation of this technique here http://www.ncbi.nlm.nih.gov/pubmed/22389033

performance:

• 94% recovery 
• 1 ml of blood processed in ~ 30 mins
• no isolation/enrichment needed

interestingly, the performance of this system was compared with cellsearch in 90 clinical samples with the following findings

91% positive samples vs 44% positive using cellsearch in 7.5 ml of blood

range of cells 15 to 3375 per 7.5ml vs 1 to 846 by cellsearch

average 305 cells/ml vs 36 cells/ml by cellsearch

very impressive performance improvement over cellsearch.

Epithelial to Mesenchymal Transition in CTCs from breast cancer patients: MGH paper published in Science

Circulating tumor cells get wanderlust

Science 1 February 2013: 
Vol. 339 no. 6119 pp. 580-584DOI:10.1126/science.1228522
Key highlights of the paper:

• Both mesenchymal & epithelial markers were expressed  in rare primary tumor cells but mesenchymal cells were highly enriched in CTCs. 
• An association of mesenchymal CTCs with disease progression was observed by serial monitoring of 11 patients
• Reversible shifts between these epithelial & mesenchymal cell fates accompanied each cycle of response to therapy and disease progression in an index patient
• Provides evidence of EMT in human breast cancer specimens, both in rare cells within primary tumors and more abundantly in CTCs. 
• The researchers found a striking association between expression of mesenchymal markers and clusters of CTCs, rather than single migratory cells.
• The proposal that mesenchymal transformation of epithelial cells is mediated by TGF-β released from platelets is supported by the researchers who note of strong TGF-β signatures in mesenchymal CTC clusters, many of which carry attached platelets
• human primary breast tumors contain rare cancer cells that coexpress mesenchymal and epithelial markers

Methods used:
Herringbone chip using an antibody cocktail (EpCAM, EGFR and Her2). Dual-colorimetric RNA–in situ hybridization (ISH) assay was used to examine tumor cells for expression of  epithelial (E) transcripts: [keratins (KRT) 5, 7, 8, 18, and 19; EpCAM (epithelial cell adhesion molecule); and CDH1 (cadherin 1)] and mesenchymal (M) transcripts: [FN1 (fibronectin 1), CDH2 (cadherin 2), and SERPINE1/PAI1 (serpin peptidase inhibitor, clade E)].

Capturing and release of circulating tumor cells (CTCs) from blood using nanopillars or other nanostructures

Capturing cancer tumor cells from the blood - MaterialsViews

This paper describes the use is 3D silicon nanopillar array coated with specific antibodies to capture and release CTCs using thermal means.

A similar approach is reported here

Scientists develop new nanotechnology to capture, release tumor cells that circulate in bloodstream

(using nano-velcro)

Nanostructured Surfaces to Target and Kill Circulating Tumor Cells While Repelling Leukocytes

(using Halloysite nanotubes)

the approach reported here is also in a similar category

Jellyfish-Inspired Device That Captures Cancer Cells from Blood Samples Could Enable Better Patient Monitoring

(using DNA tentacles)

Specific Capture and Release of Circulating Tumor Cells Using Aptamer-Modified Nanosubstrates


High-Purity Prostate Circulating Tumor Cell Isolation by a Polymer Nanofiber-Embedded Microchip for Whole Exome Sequencing

Focus review 2013: Label free microfluidic technologies for isolation of circulating tumor cells (CTCs)

Label-free isolation of circulating tumor cells in microfluidic devices: Current research and perspectives

This paper is quite comprehensive in covering the many label free approaches to CTC isolation reported so far, including, filters, accoustophoresis, magnetophoresis, etc.

The general recommendation of the paper is towards adoption of these technologies for clinical use.

undoubtedly, there are several advantages to label-free isolation of CTCs, specially filtration techniques, which are simple, inexpensive, fast and easy to use. However, there are some important limitations that need to be considered,  which I was hoping the paper would shed light upon, but didnt.

the general limitations of filtration techniques are listed here.

It was also recently reported that the deformability of tumor initiating cells is less differentiated from normal blood cells. This makes the sized and deformability based techniques vulnerable to missing these important subtypes of CTCs. This is covered here