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Patient Outcomes Linked To Biomarker Levels
JonN writes to tell us Science Daily is reporting that researchers at Yale University have discovered that current pathology methods for biomarker detection can be dramatically altered depending on the concentration of antibodies used. From the article: "Biomarkers may have the power to provide diagnostic, therapeutic, and prognostic information for personalized medicine." said Donald Earl Henson, M.D., of the George Washington University Cancer Institute, in "Back to the Drawing Board on Immunohistochemistry and Predictive Factors," an accompanying editorial. "However, immunohistochemistry, a popular technique for evaluating biomarker expression, may contain procedural flaws that jeopardize its promise."
I am not surprised as most immunohistochemical approaches to biomarkers are optimized for proteins that have notoriously variable levels depending upon sampling method and analytical method. Most basic scientists have known this for some time, and are very careful about interpretation of immunohistochemical results, but the medical field has been slow to pay attention.
As an outcome of our work in the visual system, we have been developing a new approach to biomarker analysis based upon quantitative small molecular molecular phenotyping called Computational Molecular Phenotyping (CMP) that is a much more sensitive and reliable assay for not just eyes, but just about any biological system. Small molecular signals are much more tightly regulated between subjects and even remarkably between species. CMP relies upon 1) quantitative immunohistochemistry 2) computational tools derived from methods originally developed by the CIA and NASA for remote sensing and 3) new technologies developed in-house to assist in the the data processing and analysis.
Applications are in not just in pathology such as histological analysis of oncological tissues, but also in drug development, pharmacology and basic science. Also, as an interesting aside, I have also looked not only at a variety of vertebrate and invertabrate organ systems, but I am also looking at plant tissues with these technologies and there are some very interesting results that could assist in agronomics and bioencryption.
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Can someone translate this article into English?
Ventana's been making the stuff that runs the staining process for a long time, and has done VERY well by it. Their results are outstanding and have proven to be good medicine!
I work with stuff like this on a daily basis (post doc level) and everyone in biomedical research knows to be highly suspicious of everything that has to do with immunohistochemistry and immunofluorescence. It all comes down to your negative and positive controls - as you can get a very strong signal with more antibody / less washing / longer incubation on a negative control and only a slight signal on a positive sample with less antibody / more washing / shorter incubation....
/. :-)
When reading research papers containing these images / results you need to trust the research team doing it... its so easy to falsify and way too easy to misread if you mess up your experiment slightly. Also different protocols in different labs will give different results.
But yeah, lets put obvious and well known stuff on the frontpage of
-pug
Then there's the problem of quenching. If the protein level is super high, my fluorescent signal will be too high and the dye molecules stack on top of each other, causing quenching (loss of fluorescent signal). The way around that problem is a dilution series (two would be adequate) for each test sample. Quenching is the main reason IHC and ICC suck for quantitation, too. That, and photobleaching, and other microscope artifacts. Anyone with any experience reserves IHC and ICC for qualitative information.
They mentioned the Yale scientists looked at tissue microarrays, which should not be the standard test. That technology is in its infancy, and most of its successes are either exaggerations or outright lies. Again, I'm speaking as someone in-the-know. I've seen the shiny Powerpoint presentations, and I've seen the shoddy data behind the scenes that they didn't show in the presentation. High-throughput automated microscopy? Hah. Not for another decade will that work as advertised.
And another thing: standardization of the antibody is not an issue as long as the off-rate is slow enough, and the same antibody is used for test samples and standards. I've had more than adequate experience in this arena as well, using Biacore Surface Plasmon Resonance to measure antibody on- and off-rates.
Just goes to show you, never send a doctor to do the job of a molecular biologist or biochemist.
Esa joya, esa mina y esa finca y ese mar, ese paramilitar son propiedad del Señor Matanza
At a design level, IHC is often problematic because of several key facts, especially the fact that it has to be "evaluated" by someone, using rather lax criteria. As as general rule, most observers obtain widely different results (i.e. 5-10% difference is considered very low, while 20-30% can be quite common).
I personally don't trust IHC that much, but those applications that make it to medical use have been tested many times and are reliable or at least more reliable than previous methods. In the future, new methods that combine IHC with automated fractal analysis, for example, could improve error margins. The linked article seems to promote an automated type of analysis (didn't read the nasty details) and is naturally expected to "magnify" the shortcomings of traditional IHC. I would welcome this type of technology in my lab (hate to evaluate IHC slides, let the computer do it!).
P.