Analysis of Micro-RNA Expression by qPCR on a Microfluidics Platform for Alzheimer's Disease Biomarker Discovery

Changes associated with neurodegeneration at the cellular level are manifestations of deregulated biochemical pathways, and typically precede neuronal loss. Incorporation of molecular markers in the diagnostic process could aid detection of early changes, prior to extensive neuronal loss, as early as the presymptomatic stages of the disorder, thus enabling improved patient stratification for targeted drug development. Such biomarkers should be sufficiently sensitive and specific to distinguish AD from other disorders with overlapping symptoms. Easily accessible biosamples, simple methodology, and low overall cost would enable population screening, which would not be feasible with other modalities. Non-coding (nc)RNAs have a crucial role in the entire spectrum of cellular processes, from development and differentiation to homeostatic maintenance, and have been implicated in different diseases; micro-RNAs (miRNAs) are a family of ncRNA molecules with an important role in posttranscriptional gene silencing. The early advances in the study of miRNAs as noninvasive biomarkers in cancer inspired their study for other conditions, including AD. Several deregulated miRNAs in brain, CSF, and blood have been associated with AD and other brain disorders. Their high stability makes miRNAs attractive for biomarker development, and a number of platforms are currently available for their analysis. qPCR is a technology characterized by high sensitivity and is suitable for focused analysis of specific candidates (assays) in a large number of samples. Microfluidic-based qPCR platforms have minimal RNA requirements and can yield thousands of datapoints in one qPCR experiment. Here, I present the use of miScript qPCR miRNA assays with the Fluidigm BioMark HD System.