Many biological systems and populations are complex interactions of multiple components. These parts of cellular pathways or ecological systems often interact in ways with each other that require scientists to study as much of the system as possible, instead of trying to look at individual components. Below are four examples where studying multiple markers or species has led to greater understanding of systems.
Protein Biomarker Monitoring
Monitoring multiple proteins in saliva, plasma, and urine is desirable because these samples are easily obtained from patients. Evaluating patterns of expression of multiple biomarkers is becoming increasingly important to understand healthy versus diseased patients. Biological pathways are complex systems of interactions with many proteins involved in extracellular and intracellular signaling.
“Major advantages of multiplexing are: it decreases experimental variability, simultaneously detects numerous proteins from low sample volume, obtains quantitative results and is cost effective” (Khan 2012).
Sepsis Biomarkers
Specific disease processes, such as sepsis, involve several well-known protein markers. Sepsis is often a fatal disease caused by infection and involves varying numbers of inflammation biomarkers, depending upon the infectious agent causing the disease. Researchers at Copenhagen University used commercially available cytokine panels with added unique biomarkers in order to study the most relevant set of biomarkers, and did not rely upon studying single biomarkers at a time. Studying single markers one at a time often leads to missing important interactions of proteins. Researchers generally look for increases in proteins, but some proteins may increase in abundance and others may decrease during a disease process such as sepsis. Kofoed et al. expound on the advantages of multiplexing:
“Some of the advantages of multiplexing compared with measuring the same analytes by traditional ELISA are a reduction in pipetting error; a reduction in hands-on time and, therefore, cost; and improved quality of results because freezing/thawing would typically be required for the measurement of multiple analytes by ELISA. Another advantage is the reduced amount of sample needed, which is of particular importance in children, from whom small amounts of plasma are usually obtained, and in critically ill sepsis patients, for whom there is a need for monitoring immune status at several time points.”
Drug Development
In drug development, scientists need to understand how drug candidates are affecting the disease to be treated, as well as the health of the patient. Biomarkers are often used to perform these studies during development and in clinical trials. The major advantage of multiplexing is “that you gain a better understanding of the event you are measuring in the context of another parameter, minimizing faulty interpretation of data or ambiguity from data sets” (Tenorio-Borroto et al. 2012).
Multiple biomarkers are used to monitor the effects of the drug and to insure that members of clinical trials don’t experience negative effects, such as a cytokine storm that happened during a clinical trial and led to severe issues for several members of the study. As stated by Marrer et al. (2007), “The advantages of multiplexing and microfluidics are manifold. First, the often limited sample volumes can be reduced especially when analyzing multiple biomarkers. Secondly, costs can be drastically reduced not only by analyzing several markers in a multiplex, but also by the reduction of sample volume, and consequently, the reduction of amount of reagents. Thirdly, multiplexing increases the throughput of measurements.”
Environmental Testing
Scientists take Luminex Technology and build assays for environmental monitoring to detect multiple organisms in samples. When samples are collected from the environment, scientists are often trying to detect multiple types of organisms such as bacteria, viruses, and parasites at the same time. Researchers need to monitor ocean water for the appearance of “red tides” caused by certain species of algae that are extremely toxic to other forms of marine life. Populations of aquatic animals can’t be identified in certain stages of their life cycle, which is why Gleason and Burton (2012) used multiplexing to identify fish egg species: “Suspension bead arrays have a number of benefits over other methods of molecular identification; these arrays permit high multiplexing, simple addition of new probes, high throughput and lower cost than DNA sequencing.”
- Gleason, L. U.,Burton, R. S., (2012) High-Throughput Molecular Identification of Fish Eggs Using Multiplex Suspension Bead Arrays. Molecular Ecology Resources 12:57 – 66.
- Khan, A., (2012) Detection and Quantitation of Forty Eight Cytokines, Chemokines, Growth Factors and Nine Acute Phase Proteins in Healthy Human Plasma, Saliva and Urine. Journal Of Proteomics 75:4802 – 4819.
- Kofoed, K., Schneider, U., Scheel, T., Andersen, O.,Eugen-Olsen, J., (2006) Development and Validation of a Multiplex Add-on Assay for Sepsis Biomarkers Using Xmap Technology. Clinical Chemistry 52:1284-1293.
- Marrer, E.,Dieterle, F., (2007) Promises of Biomarkers in Drug Development a Reality Check. Chemical Biology & Drug Design 69:381-394.
- Tenorio-Borroto, E., Rivas, C. G. P., Chagoyan, J. C. V., Castanedo, N., Prado-Prado, F. J., Garcia-Mera, X.,Gonzalez-Diaz, H., (2012) Ann Multiplexing Model of Drugs Effect on Macrophages; Theoretical and Flow Cytometry Study on the Cytotoxicity of the Anti-Microbial Drug G1 in Spleen. Bioorganic & Medicinal Chemistry 20:6181 – 6194.