Just making a new drug lands one step short of creating a therapy because scientists must also find a way to deliver the drug to patients. Just turn it into a pill or inject it, you may be thinking. But, it’s not always so easy, especially with protein-based drugs, known as biologics. These can be injected, but injection can take considerable skill. In addition, injectable drugs require more care in shipping. Oral drugs are the holy grail as they are easier to take and simpler to ship.
At the college of pharmacy at Ohio State University, Chris Coss, research assistant professor, and his colleagues used mass spectrometry (MS) to explore a new option. They recently used MS to characterize the plasma pharmacokinetics of novel cyclic peptides. In a cyclic protein, some part of its structure forms a ring, and the group studied how these proteins move from the blood to cells. They found that these small peptides have the ability to reach systemic circulation following oral administration. In fact, Coss and his colleagues were able to show that these proteins get into cells far more efficiently than other proteins.
That reveals just one way that scientists apply MS in the search for better therapies. “A large application of MS in preclinical research is the quantification of any number of analytes in diverse set of biological matrices,” Coss notes. “Especially when coupled with a liquid chromatography system, mass spectrometers are adept in robustly quantifying the amount of a low molecular weight analyte in a sample.”
Testing for targets
To get a drug to the right spot, scientists must first identify a target. At the Wallace H. Coulter department of biomedical engineering at Georgia Tech and Emory University, associate professor Edward Botchwey and his team look for targets to treat sickle cell disease, which causes anemia through a mutation in the hemoglobin molecules that bind oxygen in red blood cells. Specifically, Botchwey’s group looks for treatable targets in the metabolic pathway of sphingolipids in red blood cells, which he has shown to be involved in this disease.
“We use mass spectrometry to quantify sphingolipid concentrations in red blood cells from normal genotype, sickle-carrier genotype, and sickle cell–disease genotype donors,” Botchwey explains. “We can then analyze these data using computational and bioinformatics techniques to identify key differences in sphingolipids and identify novel drug targets for disease therapy.”
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Beyond targeting sickle-cell disease sites to treat with drugs, Botchwey’s group also looks at other possibilities, including the use of stem cells. As he says, “We have recently extended this form of analysis to study the membrane composition of therapeutic stem cells, and how we can use insights from MS-based lipidomic profiles to assess cell potency.”
Sensitively specific
Getting such results from MS depends on it identifying specific molecules at low concentrations. As Tiffany Payne, director of marketing, clinical diagnostic analytical instruments at Agilent Technologies, explains, “Mass spectrometry provides increased sensitivity and specificity where it is needed, for a variety of applications from endocrinology to metabolism.”
The complexity of a clinical sample also creates a challenge for analysis. “Questions are frequently aimed at the microheterogeneity of a class of compounds, such as glycoproteins in proteomics,” says Scott Kuzdzal, director of marketing at Shimadzu Scientific Instruments. “Clinical researchers may investigate the effects of diseases on such heterogeneity and look for surrogates to actively monitor diseases.” In such cases, clinical research could use MS for qualitative and quantitative analysis.
Besides being complex, clinical samples can be limited in many cases. As Kuzdzal explains, “From discovering new biomarkers for the early detection of diseases to accurately quantitating diagnostic omics assays, clinical researchers are frequently asked to ‘do more’ with very limited amounts of complex, biological samples.” That makes for a complicated analytical situation.
Beyond all of the sample constraints, medical devices must be incredibly consistent, producing the same results over time and in different labs. “Regardless of the application, clinical testing requires robust equipment that can withstand the rigors of a high-throughput clinical testing lab,” Payne explains.
Easier operation
Originally, MS demanded lots of expertise to set up and operate. To get more out of this technology in medical research, it must be easy to use. That ease expands the number of people who can use MS, and reduces the odds of making mistakes.
The problem starts with sample preparation. “A major concern in the adoption of clinical mass spec procedures is the complexity of sample prep and liquid-handling methods for optimal biospecimen processing,” Kuzdzal explains. “While mass spectrometers are exceptionally fast, the sample preparation steps are frequently manual and tedious.” For increased throughput and accuracy, that can be automated even for liquid chromatography (LC) combined with tandem mass spec (MS/MS). As Kuzdzal points out, researchers can use a platform that provides a “fully automated sample prep module for LC-MS/MS that automatically performs all o f the processes necessary for analyzing blood and other biological samples, from scanning in information from the blood collection tubes to sample pretreatment and LC-MS analysis.”
‘A major concern in the adoption of clinical mass spec procedures is the complexity of sample prep and liquid-handling methods for optimal biospecimen processing.’
That technology reveals that much of that ease of operation depends on the user interface. As Payne says, “Software that allows customers to automate analysis, data review, and reporting has made labs much more efficient and mass spec more accessible for laboratories who are using it for the first time.”
Although MS gets used today largely in medical research, it is gaining a place in clinical labs, as well, likely as a result of validated biomarkers being tested in individual assays or in panels. “For these workflows, the need for powerful software tools and robust analytical workflows increases exponentially,” Payne explains. “In the next three to five years, we anticipate that there will be more metabolite and peptide-based biomarker panels brought to market, which will focus on the early diagnosis of diseases ranging from preeclampsia to cancer.”
Most of the medical applications of MS probably lie ahead, but it is already broadly applicable. “As it turns out,” Coss says, “determining the exact mass of something is incredibly useful.” That’s precisely why so many scientists put MS to work in looking for new therapies and ways to get them to their targets as easily and efficiently as possible.
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