4 Evolving Methods for the Labeling and Mutation of Postnatal Neuronal Precursor Cells: A Critical Review

Abstract

As research on postnatal neuronal progenitor, precursor, and stem cells progresses, methods of increasing sensitivity and complexity will be brought to bear in revealing how these cell types are maintained in the adult brain and how the brain adds neurons to mature circuits. Here, we review historical and current methods, such as bromodeoxyuridine (BrdU) labeling, and discuss several emerging genetic techniques, including viral vectors, small interfering RNAs (siRNAs), and inducible transgenic/knockout mice, that will be useful for the labeling and/or mutation of adult neuronal precursor cells (NPCs). As the complexity of these methods increases, so does the potential for misinterpretation of the results. The realization must be made that all methods have inherent disadvantages and confounds, preventing conclusive and definitive interpretations if used without cross-validation. We hope to give insight into how pitfalls might be avoided and provide a primer on additional methods that might be used in the pursuit of definitive results.

In the past decade, a newfound appreciation has developed for the regions displaying neurogenesis in the adult mammal (Gage 2000; Lledo et al. 2006). In two regions, the dentate gyrus (DG) of the hippocampus and the olfactory bulb (OB), neurons are continually added after birth (Lois and Alvarez-Buylla 1994; Kuhn et al. 1996). In the hippocampus, neurons are born in the subgranular zone (SGZ) from Gfap⁺ precursor cells and migrate a short distance into the granule cell layer (GCL), where they integrate, sending an axon to CA3 and receiving input at their apical dendrite (Seri et al...