Basic Research in Hydrocephalus

James P. (Pat) McAllister II, PhD 1,2,4

1 Pediatric Neurosurgery, Primary Children’s Medical Center &

University of Utah, Salt Lake City, UT 2 Bioengineering and 3 Physiology, University of Utah, Salt Lake City, UT

Hydrocephalus Association 12th National Conference; 6/29/2012

Causes of Congenital Hydrocephalus

Causes of Intraventricular Hemorrhage

Drug treatments for brain damage

Biomechanical properties of the hydrocephalic

brain

Bioengineering for CSF Flow in Shunts and wireless

pressure sensors

Causes of Congenital Hydrocephalus

Hydrocephalus Association 12th National Conference; 6/29/2012

Fetal onset damage to ventricular walls:

1. Developing neurons (progenitors) exposed to CSF

2. Closure (stenosis) of the cerebral aqueduct

3. Activation of inflammation cells (astrocytes)

WM

VZ

VZ

SVZ

HTx E20

Figure 2

Mature Ependyma Subventricular Zone Ependymal Denudation in H-Tx Rats

A B

C D E

F

Hyh (a-SNAP) wild type

Jiménez et al. (2001) JNEN

E12.5

E13.5

E14.5

E15.5 Hydrocephalus β-III-tubulin LV

HTx rat

E18

Neural

progenitors

Progenitor cells

Ependyma/Neuroepithelium Disruption

Leads to Hydrocephalus & Abnormal Neurogenesis E M Rodríguez1, LF Bátiz1, D Sival3, MD Domínguez Pinos2, A Ortloff1, M

Guerra1, C González1, AJ Jiménez2, WFA den Dunnen3, A Ojeda1, R Yulis1,

K Vío1, RI Muñoz1, S Rodríguez1, JM Pérez-Fígares2 1 Instituto de

Anatomía, Histología y Patología, Universidad Austral de Chile, Valdivia,

Chile

Progression

Hydrocephalus Association 12th National Conference; 6/29/2012

Figure 5

Development of Hydrocephalus in Mice

Expressing the Gi-Coupled GPCR Ro1 RASSL Receptor in

Astrocytes

Journal of Neuroscience, 27(9):2309-2317;.2007.

Elizabeth J. Sweger,1 Kristen B. Casper,1 Kimberly Scearce-Levie,2

Bruce R. Conklin,2 and Ken D. McCarthy1 1Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599, and 2Gladstone Institute of

Cardiovascular Disease, University of California, San Francisco, California 94158

•Mouse line expressing Gi-coupled Ro1 receptor activated solely by synthetic

ligands (RASSL) in astrocytes

•Expressing Ro1 in astrocytes on a KOR knock-out background allowed

activation of Gi-coupled receptor signaling in astrocytes

•Crossed Ro1 line (under tetO promoter) and tet-transactivator (tTA) lines (under

control of a fragment of human glial fibrillary acidic protein (hGFAP) promoter

•Double-transgenic progeny express Ro1 only in astrocytes

•Most importantly Ro1 expression (astrocyte activation!) can be regulated using

doxycycline (dox) to bind tTA, preventing it from binding the tetO promoter

International Symposium on Fetal Neurology, Osaka, Japan; 10/23/2010

Sweger EJ, Casper KB, Scearce-Levie K, Conklin BR, McCarthy KD: Development of Hydrocephalus in Mice

Expressing the Gi-Coupled GPCR Ro1 RASSL Receptor in Astrocytes. J Neurosci 27:2309-2317, 2007.

Ro1 mice maintained off dox

develop hydrocephalus

Causes of Intraventricular Hemorrhage

Hydrocephalus Association 12th National Conference; 6/29/2012

Blood-Borne Factors

1. LPA – HA funded MYI

Drug Treatments

Hydrocephalus Association 12th National Conference; 6/29/2012

1. Anti-fibrotic agents to prevent scarring

2. Metabolic regulation of cellular water channels

(aquaporins) to increase CSF absorption

3. Transplantation of stem cells to replace damaged

neurons

4. Transplantation of choroid plexus cells to deliver

trophic substances for repair

Growth factors

• TGF-βs – Binds to and sequesters TGF-β into the extracellular matrix

(ECM)

– Anti-fibrotic agent • Positive results in renal and lung fibrosis

• Brain injury – – reduced ECM deposition of fibronectin and laminin

– reduced ED-1 positive microglia and macrophages

• Spinal cord injury – reduces the deposition of CSPGs such as NG2, neurocan, brevican and

phosphacan (axonal growth inhibition)

– reduces the amount of GFAP positive astrocytes

– Reduces accimulation of macrophages at site of injury

Ventricular volumes

Tukey – 652.92 = outlier; data not normally

distributed; transformed data (Log10)

Kaolin Kaolin Kaolin &

& PBS TGFβ Ant

n=5 n=6 n=5

Ve

ntr

icle

vo

lum

e (

mm

3)

Kaolin Kaolin Kaolin &

& PBS TGFβ Ant

p=0.0006

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Dias 12

University Clinic of Neurosurgery

Background

• Aquaporins (AQP) are proteins that facilitates water transport through the cell membrane. Transport rate and direction highly dependent on co-tranporters. (Macaulay and Zeuthen 2009)

Mahmood Amiry-Moghaddam and Ole P. Ottersen Nature Reviews Neuroscience 4, 991-1001, December 2003

• The orthodox AQPs 1 and 4 are expressed in brain under normophysiological conditions. (Mahmood Amiry-Moghaddam and Ole P. Ottersen 2003)

• Possible the unorthodox AQPs 9 and 11 are also expressed, role unclear. (Amiry-Moghaddam et al

2010)

• AQP4 most abundant in brain. Localized in perivascular endfeet and enpendymal cells. Blood-tissue and tissue-CSF borders. (Nielsen et al

2003)

• AQP4 involved in brain water metabolism and possible cell migration. (Amiry-Moghaddam et al 2010)

Biomechanics

Hydrocephalus Association 12th National Conference; 6/29/2012

1. Del Bigio MR et al (U of Manitoba, Canada Research Chair in

Developmental Neuropathology):

measuring brain stiffness with an indenter device

in hydrocephalic animals

2. Luciano MR et al (Cleveland Clinic, NIH 5R01NS060916-02,

Improving Cerebral Blood Flow Through Direct Control of CSF

Pulsations):

CSF Flow – Bulk vs. Pulsatile

Cerebral Aqueduct

Bulk flow ~ 0.3 cc/min

Pulsatile flow ~ 2 cc/min

Pulsatile Flow

Slower in cerebral aqueduct &

over cortical surface

Faster in basal cisterns

Flow Speed

Basal Cisterns

Cerebral

Aqueduct

Hydrocephalus Association 12th National Conference; 6/29/2012

Bioengineering for CSF Flow in Shunts

and wireless pressure sensors

Hydrocephalus Association 12th National Conference; 6/29/2012

1. Aqueduct Neurosciences (NIH 1R41NS074616-01, Samuel Browd,

Hydrocephalus: Reducing Catheter Failure and Improving Diagnostic

Capabilities)

2. Infoscitex Corp (NIH 5R44NS056628-03, James Goldie, Microfabricated

Implantable Flowmeter for CSF Shunts Phase II)

3. Transonic Systems, Inc. (2 R44 NS049680-02, Cor Drost, A Flow

Monitor for Pediatric Hydrocephalic Shunts)

4. NeuroDX Development LLC (NIH 2 R44 NS067772-02, Marek

Swoboda, Validation of ShuntCheck-Micro-Pumper, a non-invasive

diagnostic procedure for detecting shunt patency or occlusion in pediatric

hydrocephalus patients

•Significant difference compared to Bare Hydrophobic Control

(p < 0.05)

** Significant difference compared to Oxidated Hydrophilic

Sample (p < 0.01)

Statistical Power > 0.98 for all comparisons to the Bare

Hydrophobic Control

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Macrophage Adhesion