Type of publication:
Booth J., *Lacy-Colson J., Norwood M., Murray C.
Gut, June 2014, vol./is. 63/(A124-A125), 0017-5749 (June 2014) (also published in European Journal of Cancer, July 2014, vol./is. 50/(S240), 0959-8049 (July 2014))
Background: In vitro diagnostic tests are being developed to evaluate informative protein or DNA biomarkers in stool or blood samples. Stool samples are inconvenient to collect and handle, and may suffer from contamination that interferes with molecular assays. Blood samples may not be as informative early in the disease process. Studies have shown that significant numbers of exfoliated cells and their products are retained in a muco-cellular layer overlaying the colonic mucosa, but distinct from the stool, and that this material flows toward the rectum, where it can be captured for analysis. Materials and Methods: Origin Sciences (OS) has developed a novel sampling device that incorporates an inflatable nitrile membrane. Following insertion into the unprepared rectum via a standard proctoscope, the membrane is inflated to make contact with the rectal mucosa for 10 seconds. The membrane is then deflated and retracted into the device prior to removal from the patient. Upon retraction the sampled material is retained on the inverted membrane, which acts as a receptacle for the addition of buffer preserving the material for subsequent analysis. Results: The sampler has now been tested in over 2000 patients and healthy volunteers, and has shown excellent acceptability. Tests and in vitro experiments with monolayers of cultured human cells indicate that the membrane captures intact cells, which are easily washed off the membrane for further investigation. Detailed evaluation of the mucous-associated material captured by the device, in both normal and diseased states, shows it to be rich in protein and nucleic acids. Levels of soluble protein present in standard 3 mL capture buffer varied between 90 and 3000 mug/mL, with a mean of 710 mg/muL. OS has detected informative auto-antibodies of isotypes IgA, IgG, and IgM by ELISA in the protein component of these preparations. These preparations are also rich in nucleic acids; DNA was found at levels ranging from 0.5 to 21.9 mg/muL. This DNA appears to retain a high degree of integrity, since a number of informative genes have been detected by quantitative PCR. Conclusions: The sampling device represents a novel and minimally invasive tool for capturing biomarker-rich material from the unprepared rectum. With minimal contamination by stool, the material collected is readily analysable. In principle this device lends itself to point-of-care testing for a range of indications, including infectious and inflammatory diseases of the GI tract, in addition to malignancy.
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