In Vivo Optical Imaging and Manipulation of Brain Pericytes

Abstract

IntroductionPericyte serve myriad roles in the developing and adult brain, but many of their functions remain poorly understood. In less than a decade, the advent of new tools and approaches has revolutionized brain pericyte research by enabling direct visualization of pericyte structure and function in the living mouse brain. In addition to accessing pericytes in a physiological context, in vivo imaging has revealed fascinating new biology on how distinct pericyte subtypes influence cerebral blood flow in both health and disease. This chapter highlights novel approaches and provides up-to-date guidance on pericyte research using two-photon microscopy and related optical applications.MethodsWe surveyed literature for studies that have imaged brain pericytes in vivo in order to summarize their methodologies and approaches. Keywords included pericyte, mural cell, cerebrovasculature, brain, capillary, blood-brain barrier, cerebral blood-flow, two-photon microscopy, cranial window, endothelium, cre recombinase, in vivo imaging, microvasculature, calcium imaging, cell ablation.ResultsWe discuss the identification of true capillary pericytes and set them apart from transitional phenotypes in murine cerebral cortex. An array of available murine Cre drivers and other approaches to target pericytes and brain mural cells are compared and contrasted. Surgical and experimental parameters to perform rigorous quantification of pericyte influence on capillary flow and integrity are also discussed. Lastly, we move beyond correlative observation to cutting-edge approaches for optical ablation and manipulation of pericytes, concomitant with real-time imaging of cerebrovascular function.ConclusionThe information provided can serve as a roadmap to rigorous in vivo imaging of pericytes in the healthy and diseased brain.