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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
0
20
40
60
80
100
120
Bare
Silicone
OH-
Silicone
NAC-OH-
Silicone
Me
an
Ma
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ph
ag
e A
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ion
(% C
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)
*
**
OH-PDMS, Top Half
Control Silicone
OH-Silicone
NAC-OH-Silicone
NAC Reduces
Macrophage Adhesion