Research

The morphology and biochemistry of nanostructures provide evidence for synthesis and signaling functions in human cerebrospinal fluid

Michael G Harrington¹ , Alfred N Fonteh¹ , Elena Oborina¹ , Patricia Liao¹ , Robert P Cowan¹ , Gordon McComb² , Jesus N Chavez³ , John Rush⁴ , Roger G Biringer⁵ and Andreas F Hühmer⁵

¹  Molecular Neurology, Huntington Medical Research Institutes, Pasadena, CA, 91101 USA

²  Neurosurgery, Children's Hospital of Los Angeles, Los Angeles, CA 90027 USA

³  Neural Engineering, Huntington Medical Research Institutes, Pasadena, CA, 91101 USA

⁴  Cell Signaling Technology, Danvers, MA 01923 USA

⁵  Proteomics, Thermo Fisher Scientific, San Jose, CA 95134 USA

author email corresponding author email

Cerebrospinal Fluid Research 2009, 6:10doi:10.1186/1743-8454-6-10

Published:	7 September 2009

Abstract

Background

Cerebrospinal fluid (CSF) contacts many brain regions and may mediate humoral signaling distinct from synaptic neurotransmission. However, synthesis and transport mechanisms for such signaling are not defined. The purpose of this study was to investigate whether human CSF contains discrete structures that may enable the regulation of humoral transmission.

Methods

Lumbar CSF was collected prospectively from 17 participants: with no neurological or psychiatric disease, with Alzheimer's disease, multiple sclerosis, or migraine; and ventricular CSF from two cognitively healthy participants with long-standing shunts for congenital hydrocephalus. Cell-free CSF was subjected to ultracentrifugation to yield supernatants and pellets that were examined by transmission electron microscopy, shotgun protein sequencing, electrophoresis, western blotting, lipid analysis, enzymatic activity assay, and immuno-electron microscopy.

Results

Over 3,600 CSF proteins were identified from repeated shotgun sequencing of cell-free CSF from two individuals with Alzheimer's disease: 25% of these proteins are normally present in membranes. Abundant nanometer-scaled structures were observed in ultracentrifuged pellets of CSF from all 16 participants examined. The most common structures included synaptic vesicle and exosome components in 30-200 nm spheres and irregular blobs. Much less abundant nanostructures were present that derived from cellular debris. Nanostructure fractions had a unique composition compared to CSF supernatant, richer in omega-3 and phosphoinositide lipids, active prostanoid enzymes, and fibronectin.

Conclusion

Unique morphology and biochemistry features of abundant and discrete membrane-bound CSF nanostructures are described. Prostaglandin H synthase activity, essential for prostanoid production and previously unknown in CSF, is localized to nanospheres. Considering CSF bulk flow and its circulatory dynamics, we propose that these nanostructures provide signaling mechanisms via volume transmission within the nervous system that are for slower, more diffuse, and of longer duration than synaptic transmission.