Gold nanoparticle-enhanced X-ray microtomography of the rodent reveals region-specific cerebrospinal fluid circulation in the brain

Abstract

Cerebrospinal fluid (CSF) is essential for the development and function of the central nervous system (CNS). However, the brain and its interstitium have largely been thought of as a single entity through which CSF circulates, and it is not known whether specific cell populations within the CNS preferentially interact with the CSF. Here, we develop a technique for CSF tracking, gold nanoparticle-enhanced X-ray microtomography, to achieve micrometer-scale resolution visualization of CSF circulation patterns during development. Using this method and subsequent histological analysis in rodents, we identify previously uncharacterized CSF pathways from the subarachnoid space (particularly the basal cisterns) that mediate CSF-parenchymal interactions involving 24 functional-anatomic cell groupings in the brain and spinal cord. CSF distribution to these areas is largely restricted to early development and is altered in posthemorrhagic hydrocephalus. Our study also presents particle size-dependent CSF circulation patterns through the CNS including interaction between neurons and small CSF tracers, but not large CSF tracers. These findings have implications for understanding the biological basis of normal brain development and the pathogenesis of a broad range of disease states, including hydrocephalus.

Postnatal meningeal CSF transport is primarily mediated by the arachnoid and pia maters and is not altered after intraventricular hemorrhage-posthemorrhagic hydrocephalus

“…The perimesencephalic cisterns separate two functionally-distinct regions—the hippocampus and the midbrain. This, in conjunction with the results of our present study showing diffuse 15-nm AuNP movement into only the hippocampal side of the quadrigeminal, and ambient cisterns, but not the midbrain, suggest that these cisterns may serve to facilitate a regionalized CSF-brain parenchyma cross talk [ 34 – 37 ]. Alternatively, their location in between the LV and 3V may serve as a potential route for inter-ventricular CSF transport and communication [ 21 ].…”

“…After intracardial perfusion sacrifice 10 min post-1.9-nm AuNP injection and 4 h post-15-nm AuNP injection, the entire rodent body was placed in 4% paraformaldehyde at 4° C overnight, embedded in 2% agarose, and imaged within 72 h of sacrifice with a Zeiss Versa 520 X-ray microscope (Carl Zeiss Imaging, White Plains, NY) using a 0.4 × flat panel detector as previously described [ 37 ]. The X-ray source was tuned to 50 kV at 4W to optimally excite gold particles.…”

Cerebrospinal Fluid Flow Extends to Peripheral Nerves

“…In contrast, adeno associated virus at 25nm is usually excluded by the BBB/BNB unless leakage is induced, or neurotropic selected serotypes are used (46–48). Recent CSF flow studies using both gold and other nanoparticles have shown restricted flow patterns within the CNS for particles of 20-40nm compared to 3-5-4.5nm, further supporting our size selections (5, 6, 49, 50). Therefore, 1.9nm nanogold would be small enough to potentially transverse the BBB/BNB while 15nm nanogold particles should be mostly excluded.…”

“…The smaller 1.9nm nanogold traced expected patterns of CSF flow within the central nervous system flowing from the infused ventricles, throughout the brain and spinal cord (Fig. S2) (49). 1.9nm nanogold distribution, however, extended beyond the CNS to the PNS, including distal peripheral nerves (Fig.1,4 and S1).…”

Current progress and challenges in the development of brain tissue models: How to grow up the changeable brain in vitro?

“…Recent data suggest that not only local blood supply, but also CSF movement from lateral and third ventricles to neurogenic niches might contribute to adjusting the rate of neurogenesis to actual demand of developing and active brain. 102 Since embryonic and adult neurogenesis has been extensively described in details elsewhere, 103 – 106 we are going to focus here on a role of BBB and BCSFB in the regulation of adult neurogenesis stimulated in experience-driven brain plasticity and repair of lesioned brain tissue.…”