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The presence of nucleic acids in serum and other biological fluids has long been recognized. Efforts to use these elements as biological markers, or biomarkers, are attractive due to the accessibility of biofluids and the potential of biomarkers to provide useful, reproducible and objective information on the normal or pathological state of a biological process. Tools that can efficiently isolate nucleic acids from biofluids, along with assays, kits or panels that can interrogate nucleic acid content are all supplied by Meridian , with an ISO 13485 level of manufacturing that offers the quality required to move research efforts towards successful application.

Biomarkers – Approaches and Techniques

A biomarker can be defined as “a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacologic responses to a therapeutic intervention.1

Biomarkers can be classified into different types and used for a variety of purposes:

  • Prognostic: identification of individuals at risk of specific outcomes
  • Predictive: stratification or categorization of individuals based on predicted response to treatment
  • Monitoring: indicators of disease progression or therapeutic efficacy
  • Pharmacodynamic: surrogate end-points used to demonstrate proof of principle during early-stage drug development

There are biological markers applicable to most disease states and conditions and the study and analysis of them has been central to the field of epidemiology for decades. More recently, with an increase in genetic understanding, biomarkers have shifted into the world of personalized medicine – identifying individual differences within patient groups in order to dictate treatment options, guide drug dosage and bring other improvements to therapeutic decision making.

Biomarkers also feature heavily in the drug development process. In a time where new drug approval rates are in a declining state, biomarkers that can predict efficacy or safety of a drug are in particular demand. Oncology research and clinical care are also looking at biomarkers as ‘liquid biopsy’ alternatives for screening, monitoring and characterizing tumors, using circulating cell-free tumor DNA, circulating tumor cells, as well as circulating miRNAs.

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Use of miRNAs as Biomarkers

Using miRNAs as biomarkers is an attractive option as they carry specific information about the patho-physiological state of an individual.

With the prominent role miRNAs play in cellular processes, there is a growing list of diseases linked to aberrant miRNA expression and researchers have now identified cancer-regulating miRNAs that negatively regulate tumor suppressor genes and oncogenes. Research has also shown miRNA expression to be highly specific within different tissue types, as well as in response to various stimuli, such as drug or chemotherapy, thus miRNA signatures carry promising prognostic and predictive potential.

While much of the miRNA activity is intracellular, there is a significant number of extracellular miRNAs observed in various body fluids. The full role of circulating miRNAs is still being elucidated, but it is thought that these elements play a role in cellular communication and the regulation of gene expression throughout the body. Most RNA molecules are highly unstable in the extracellular environment, thus it is surprising that circulating miRNAs exhibit excellent stability, even after exposure to harsh treatments such as boiling, extreme pH changes, or long-term storage. These excellent stability characteristics in conjunction with miRNA dysregulation in disease states, make circulating miRNAs a very suitable biomarker option.

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Biomarkers – Technical Challenges

Successful application of biomarker analysis is still limited by a number of technical considerations, starting with the inherent design and statistical challenges present in all biological research.

It is essential to use tools that provide accurate and reproducible results using data that holds statistical significance regarding the population or disease under study. The nucleic acid isolation, preparation and amplification reagents offered by Meridian are designed for sensitive and robust results, made with an ISO 13485 quality rating to bring confidence in quality and allow for downstream transfer to applied or clinical settings.

When choosing biomarker candidates, biological relevance and diagnostic capacity are important factors to consider, along with understanding the extant complexity of the biological environment. Although miRNAs are attractive options, there are many examples where the same miRNA is linked to a number of different diseases, ultimately leading to questionable diagnostic utility.

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1. Biomarkers and surrogate endpoints: preferred definitions and conceptual framework. Biomarkers Definitions Working
Group. Clin Pharmacol Ther. 2001 Mar; 69(3):89-95.