Isolation of Viral-Infected Brain Regions for miRNA Profiling from Formalin-Fixed Paraffin-Embedded Tissues by Laser Capture Microdissection.

Brain is a highly heterogeneous organ with numerous layers of specialized cells. Viral infection further adds complexity to downstream analysis because only a subpopulation of the brain is infected. In these instances, molecular changes that occur within infected cells are not truly reflected when whole tissue is used for downstream analysis. Laser capture microdissection (LCM) is a tool that allows for the selection and isolation of cells or regions of interest as determined by microscopic observation. It provides a platform for visually selecting the tissue that truly represents the material one wishes to study, such as viral infected cells. Formalin-fixed paraffin-embedded viral-infected tissue allows for safe handling and processing by LCM. Here, we describe a method whereby viral-infected regions of the brain were specifically isolated by LCM from the rest of the FFPE tissue. The isolated regions were then used to extract RNA for microRNA profiling. This approach can be applied to study microRNA changes from any viral infection in any given tissue.