The emerging field of metabolomics would be hobbled by irresolvable technical challenges were it not for the expanding availability of user-friendly and affordable mass spec instruments. A German Research Center for Environmental Health conference, “Metabolomics & More—the Impact of Metabolomics on the Life Sciences,” held last month in Munich, showcased a range of initiatives under way in commercial and academic labs that harness the power of mass spectrometry to measure and monitor the metabolome.
Klaus Weinberger, Ph.D., CSO of Biocrates, is a fan of targeted metabolomics because it allows his company to “scale-down analytical challenges and produce an accurate reflection of environmental influences on the individual subject.” Dr. Weinberger discussed Biocrates’ progress in uncovering new biomarkers of metabolic conditions at the meeting. “We focus on a number of current issues, including diseases with long latent phases, complex health conditions such as diabetes, and improvement of current diagnostics.”
There is a paradigm shift afoot in the field of clinical diagnostics, in which high-resolution biochemical characterization of body fluids by targeted metabolomics is being counted on to facilitate the development of function-oriented diagnostics, moving from expensive immunoassays to cheaper, more specific, and more accurate mass spec assays. These new diagnostics are much more than just a positive or negative test for the condition, they also allow detailed subtyping and staging, which will direct personalized therapeutic regimens, Dr. Weinberger said.
Biocrates is concerned with a range of diagnostic markers, including screening markers for early diagnosis, prognostic biomarkers that measure disease progression, theranostic markers for optimizing drug protocols, and markers of inborn metabolic diseases for newborn screening.
The concept of inborn errors of metabolism harkens back over a century when it was first formulated by Sir Archibald Garrod, who recognized that certain diseases in newborns were the result of gene defects causing metabolites to pile up in their serum and urine. Diseases such as phenylketonuria have long been part of the neonatal testing repertoire, but the traditional methods tested for only one possible genetic disorder at a time.
It is now possible to screen newborns for a whole range of conditions, instead of using laborious and expensive one-shot assays, Dr. Weinberger said, adding that Biocrates has developed a screen for 20 to 30 single gene diseases.
Studies at Biocrates have demonstrated that mass spec-based diagnostics can provide much greater coverage, while at the same time, covering a greatly expanded range of diseases, Dr. Weinberger explained. Specifically, quantitative tandem mass spec with stable isotope dilution will meet stringent quality criteria. Depending on the needs of the diagnosis, researchers can use either a targeted metabolomics approach or metabolic profiling with a LC/MS full scan.
Biocrates’ integrated technology platform combines sample preparation, analytics, and bioinformatics, which permits the processing of large numbers of samples. “Our platform can be applied to a wealth of areas, such as basic investigations, agricultural research, drug discovery, and clinical diagnostics and therapeutics.”
Metabolomes Under Stress
“Measuring and monitoring the metabolome are perhaps two of the most daunting challenges of the 21st century,” according to Herbert Hill, Ph.D., professor at Washington State University. Our current level of ignorance is illustrated by the fact that estimates for the number of metabolites in the human and plant metabolomes range from around 2,800 to well over 200,000. And these compounds run the gamut from polar to nonpolar, with examples of every conceivable functional group. Indeed, some classifications are so weighty that they require their own subclassification such as the lipodome and the glycome.
Chirality and a profusion of isomers add to the challenge. While nuclear magnetic resonance (NMR) and Fourier-transform infrared spectroscopy have been utilized for analysis of the metabolome, both approaches have their limitations. For this reason, Dr. Hill and his collaborators have focused on ion mobility mass spec (IMS) to analyze bodily fluids.
“When coupled with mass spec, ion mobility spectrometry offers value-added data not possible from mass spec alone,” Dr. Hill explained. “Indeed, the two methods complement and match one another like a hand in glove and effectively become one analytical instrument.”
Dr. Hill’s team has confirmed the power of this technology through metabolomic studies of lymphatic fluid from rats monitored while under dietary stress. Nutritional deprivation as well as diabetes and obesity may cause various metabolic changes, which, in turn, could lead to cancer and cardiovascular disease, so the ability to closely monitor the metabolome could be a critical tool in understanding and eventually treating these conditions.