Biology Reference
In-Depth Information
4
Choroid Plexus and Immune
Response of the Brain
Cesar V. Borlongan, Dwaine F. Emerich
Department of Neurosurgery, University of South Florida, Tampa, FL, and
InCytu, Inc., Providence, RI
4.1 Introduction
The choroid plexuses (CPs), located within the ventricles of the brain, produce the cere-
brospinal fluid and form an interface between the peripheral blood and the CSF. Key
functions related to brain homeostasis that have been ascribed to CP include processes
that establish, survey, and maintain the biochemical and cellular status of the brain
under normal and pathological conditions. Recent evidence implies that CP is a suitable
source of transplantable immune factor- and tropic factor-secreting cells with neurore-
generative and neuroprotective capabilities. Indeed, conditioned media from CP pro-
motes neurite outgrowth and prevents the death of cultured embryonic neurons
[1-3]
;
furthermore, CP transplants promote regeneration of damaged spinal cord and reduce
the functional and structural consequences of brain trauma in animal models of stroke
[1,4]
. In parallel, transplanted encapsulated neonatal porcine CP also exerts neuropro-
tective effects in rat
[5]
and monkey models of Huntington's disease (HD)
[3]
. In this
chapter, we describe the role of the CP in brain development, normal brain homeostasis,
immune surveillance, and aging, and also discuss representative CNS disorders affected
by abnormal CP functions. Finally, we draw from recent laboratory findings demon-
strating the efficacy and safety of transplanting CP cells for treating brain disorders.
4.2 Choroid Plexus: Basic Structure and Function
Gross examination of the CP reveals its basic structure as lobulated with a single con-
tinuous layer of cells derived from the ependymal lining of the ventricles (
Figure 4.1
).
The intricate morphology of the CP originates from its fronds projecting into the
fluid-filled ventricles, which is thought to allow the CP to perform complex func-
tions. The inner layer of the projections contains a densely enriched bed of vascular
supply interspersed between connective tissue and epithelium. On basal lamina rest
choroidal epithelial cells, which form a large central spherical nucleus with abun-
dant cytoplasm possessing numerous villi on their luminal surface (
Figure 4.2(A)
).
