When thinking about cancer treatments and its development over the years, it is remarkable to think of how advanced treatments have become. The administration of toxic chemicals and radiation is evolving into much more focused treatments that specifically target molecule/receptor interactions. This latest idea involving the use of ‘tentacles’ to effectively filter cancer cells from the bloodstream is another foray into the more intricate side of detecting cancer – all from using the humble DNA molecule.

The Theory

A microfluidic chip that contains a weaving pattern of a very long, thin channel is laced with DNA strands that stretch around a few hundred microns long (1 micron = 0.001 millimetres) that are attached to the walls of the channels. Each DNA strand is made up of “aptamers” – sequences of nucleic acids that are specific to target a certain protein present on a leukaemia cancer cell; in this case the tyrosine kinase-7 protein. This protein is present on most cancer cell surfaces, especially the lymphoblast CCRF-CEM cells that were filtered most effectively in this study.

The cells become attached to the DNA strands as they interact with the aptamer sequences and are therefore filtered from the blood sample. With the help of a herringbone pattern on the base of the channels (which creates a whirlpool effect to the sample, effectively increasing the flow time through the chip) the study claims that they gathered results pointing to a much more efficient means of capturing these cells, much higher than that of leading cell-capture microfluidic devices.

Why is this useful?

Such technology allows for the identification of cancer cells within the blood. This can be used as purely a diagnostic test for possible cancer or attempting to detect possible metastases of cancer cells from a tumour to another site of interest. This is particularly useful in the fight against leukaemia. As leukaemia is a blood-borne cancer, it is vital to detect signs of possible cancer cells as soon as possible. Furthermore, for leukaemia patients that are going through remission, detecting the signs of a possible relapse increase the chances of successful secondary treatment.

Jellyfishlike microchip scoops cancer cells right out of the blood stream
DNA strands (green) drift down into the bloodstream and attach to blood droplets (red)

The device used in this study was tailor-made for a specific molecule on the cell surface of lymphoblast cells however there are many more possibilities to this as a diagnostic tool. Instead of a tyrosine kinase-7 aptamer being used to trap the metastasis cells, the DNA sequences can be altered to interact with other proteins on the cell surface. This opens the door to using the device not only as a diagnostic tool for leukaemia, but for a wide range of cancers.

A further exciting possibility for this practice is in the development of “personalised” treatments. It is becoming more and more clear that a successful treatment for one person’s cancer does not mean it will be successful for someone elses. By using this device and manipulating the aptamer sequences present in the DNA tentacles, it becomes clear what proteins are present on that particular cell surface. The cells can then be cleaved from the DNA sequences and further tested to see exactly which proteins are more prominent than others and then specific treatment regimes can be devised for treating those particular cells, specific to the individual the original cell would have been taken from. This would particularly come in useful to see if a particular treatment has left behind any resistant cells if the test is carried out both before and after a round of chemotherapy.

Looking Past Cancer

It can even stretch further than the practice of oncology as virus proteins or bacterial proteins can also have aptamers designed to interact with them and placed in the DNA tentacles. It can even be applied to possible prenatal testing by targeting fetal cells present in a mother’s bloodstream. Tests can then be carried out on the captured cells to diagnose a range of possible diseases.This would be a lot more favourable than the more invasive procedure of amniocentesis that is the go-to for prenatal testing.

The possibility’s for this kind of technology are numerous and has produced yet another exciting development in providing quicker and more accurate diagnosis of life-threatening disease, as well as the possibility of producing much more targeted therapies for each individual. Something which is more in-demand than ever.

References:

Huffington Post article: http://www.huffingtonpost.com/2012/11/21/jellyfish-inspires-cancer-detector_n_2173325.html

Original paper abstract: http://www.pnas.org/content/early/2012/11/08/1211234109.abstract

Image courtesy of:

http://www.engadget.com/2012/11/14/jellyfish-inspired-microchip-captures-cancer-cells/

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