Paper Commentary: SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter - Lab on a Chip (RSC Publishing)

SSA-MOA: a novel CTC isolation platform using selective size amplification (SSA) and a multi-obstacle architecture (MOA) filter - Lab on a Chip (RSC Publishing)

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Update (10 Feb, 2013): A follow up improvement of this technology has been published here
performance: 95% isolation efficiency, 59% purity from 3 ml of blood (total isolation time ~ 30 mins)
no results from clinical samples were reported.

another recent publication from Samsung in Biomicrofluidics 
an older publication from Samsung advanced Institute of Technology can be found here
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Summary:

This paper presents a novel method of enriching CTCs by combining EpCAM based bead tagging followed by size filtration. The basic premise of this paper is that purely size-based techniques suffer from size overlap between CTCs and WBCs. To overcome this, CTCs are selectively tagged with 3 micron polymer beads to enhance their size, followed by filtration through a lateral filter surface. recoveries of upto 99.1% are reported in spiked cells.

Advantages:

• Results show that the size enhancement seems to work in appropriately discriminating between WBCs and MCF-7 cells

Limitations:

• Fundamentally, this is an antigen dependent technology, hence belongs to positive enrichment family of techniques. Its inherently limited by antigen expression and its variability as well as the efficiency of binding interaction.
• There are other known cancer cell lines which are smaller than the MCF-7 cells, how does this technique work with smaller cancer cells? smaller cells will require larger beads for effective differentiation, however, steric hindrance will become a factor between adjoining binding sites
• silicon manufacturing technology is expensive as it is. it is unclear how expensive is the silicon on glass technology
• throughput is 20ul/min, which is considerably lower than size filtration systems, which have reported as fast as 2 mls in 5 minutes. the overall assay time is also increased due to the need to pre-conjugate beads to cells
• the effect of occupancy of antigen binding sites by microbeads on downstream molecular characterization of tumor cells
• lack of clinical data
• lateral flow filtration is inherently limited by the requirement of scaling for higher throughput versus large area staining and imaging requirement

other considerations:

1. http://www.clearbridgebiomedics.com/ --> has a platform for size and deformability based CTC isolation
2. cell size enhancement product is available here  http://pluriselect.com/home.html, 
3. how is the performance of this paper in comparison to item 2 above, which should be relatively inexpensive and has a higher thorughput