Visualizing flow in an intact CSF network using optical coherence tomography: implications for human congenital hydrocephalus

Engin Deniz,Priya Date,Kristopher T. Kahle,Pascal Ackermann,Charuta Furey,Ina Berenice Fink,Mustafa K. Khokha,Stephan Jonas

doi:10.1038/s41598-019-42549-4

Abstract

Cerebrospinal fluid (CSF) flow in the brain ventricles is critical for brain development. Altered CSF flow dynamics have been implicated in congenital hydrocephalus (CH) characterized by the potentially lethal expansion of cerebral ventricles if not treated. CH is the most common neurosurgical indication in children effecting 1 per 1000 infants. Current treatment modalities are limited to antiquated brain surgery techniques, mostly because of our poor understanding of the CH pathophysiology. We lack model systems where the interplay between ependymal cilia, embryonic CSF flow dynamics and brain development can be analyzed in depth. This is in part due to the poor accessibility of the vertebrate ventricular system to in vivo investigation. Here, we show that the genetically tractable frog Xenopus tropicalis, paired with optical coherence tomography imaging, provides new insights into CSF flow dynamics and role of ciliary dysfunction in hydrocephalus pathogenesis. We can visualize CSF flow within the multi-chambered ventricular system and detect multiple distinct polarized CSF flow fields. Using CRISPR/Cas9 gene editing, we modeled human L1CAM and CRB2 mediated aqueductal stenosis. We propose that our high-throughput platform can prove invaluable for testing candidate human CH genes to understand CH pathophysiology.

Highlights

Cerebrospinal fluid (CSF) flow in the brain ventricles is critical for brain development
We expand this platform to analyze in vivo CSF dynamics during ventricular development and use this approach to better understand the pathogenesis of patients with congenital hydrocephalus
We show that Xenopus, coupled with Optical Coherence Tomography (OCT) imaging, enables the simultaneous visualization of brain ventricle development, CSF flow dynamics, and ependymal cilia function

Summary

Introduction

Cerebrospinal fluid (CSF) flow in the brain ventricles is critical for brain development. While recent studies in single brain ventricular explants have highlighted potential complexities of CSF flow fields[15], a global understanding of these networks in an intact, multi-compartmental ventricular system remains rudimentary This is in part due to technical limitations of accessing the brain ventricles in a live animal through the rigid cranial vault and multilayered cortex, which impedes real-time imaging. We recently demonstrated that OCT imaging effectively detects structural changes in Xenopus craniofacial and cardiac structures, a useful screening tool for human genetic cranio-cardiac malformation research[24] We expand this platform to analyze in vivo CSF dynamics during ventricular development and use this approach to better understand the pathogenesis of patients with congenital hydrocephalus

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