Fazli R. Awan Characterization of a Mouse Model of Sandhoff Disease by Magnetic Resonance Methods Supervisors Dr Fran M Platt Prof Peter Styles

Sandhoff Disease A type of Glycolipid (i.e. Glycosphinoglipid) lysosomal storage disorder Defect in the  -gene of the enzyme  - Hexosaminidase A (  ) and B (  ) A neurodegenerative disease Knockout mouse model for Sandhoff disease

Head tremor Muscle weakness Ataxic gait Motor dysfunction Hind limb paralysis Immobile unresponsive state Humane end point Natural death Age in Weeks Disease Progression in Sandhoff Mice 2-Month3-Month4-Month

What mouse models could tell us about the diseases? Much about the biochemistry, pathology and clinical course of the disease BY……. Various biochemical and immunohistology methods In Vitro or Ex Vivo (a main limitation) BUT ?

To find out disease related changes in Sandhoff mice by in vivo MR methods Aim

400 MHz Vertical Bore Magnet Mouse head Mouse here Anaesthesia and Scavenging tubes Portion of the Probe showing coil region

Anaesthesia RF cable Data acquisition Magnet RF coil Heating blanket Water pipe Body temperature Heart rate / ECG Mouse

IMAGING PROTOCOL

MRI Scans Brain water diffusion studies by ADC mapping T2 and T1 Relaxation Times Magnetization Transfer Ratios (MTRs) Cerebral blood flow (CBF) by ASSIST-MRI

MRI Data Analysis In whole brain HorizontalSagittal

MRI Data Analysis In specific regions

STUDY DESIGN (Disease stages studied in Sandhoff mice) Presymptomatic (2 month) Early symptomatic (3 month) Terminal stage (4 month)

Apparent Diffusion Coefficient (ADC) Decreases in Sandhoff Mice * Whole-brain 8% ↓ Diffusion of water in Sandhoff mouse brain is low

Sandhoff Control Bins on x-axis in all of the above histograms represent ADC (10 -5 mm 2 /sec) ADC Histograms for 4-Month-Old Mice

* Decrease in ADC in the cerebral cortex of Sandhoff mouse brain ADC Analysis in Specific Regions of Sandhoff Mouse Brain Water diffusion in Sandhoff mice was low at all the three ages, in almost all of the brain regions investigated. 11% ↓

T2 (Spin-Spin) Relaxation Time (Reduced in Sandhoff Mouse Brain ! ) ** In whole-brain 8% ↓

Histograms for T2 Relaxation Time in 4-Month-Old Mice Sandhoff Control Bins on x-axis in all of the above histograms represent T 2 relaxation time (msec)

T2 Relaxation Time Decreases with disease progression * ** (A) (B) T2 relaxation time: Increases in controls from 2- 4 month Decrease from 2-4 month in Sandhoff mice

T1 (Spin-lattice) Relaxation Time (Decreases in Sandhoff Mouse Brain ! ) * * ** 4-month-old Sandhoff and control mice

Magnetization Transfer Ratios (MTRs) (in Sandhoff and Control Mouse Brain) Lower MTRs in 3 month Sandhoff mice Higher MTRs in 4 month Sandhoff mice BUT NOT SIGNIFICANTLY

Cerebral Blood Flow (CBF) (Measured by ASSIST-MRI) * * CBF increases in Sandhoff mice with disease progression

* * Cerebral Blood Flow (CBF) (comparison of 4-month-old mice)

Summary ADC (water diffusion in the brain) reduces in Sandhoff mice as compared to their age-matched controls T2 relaxation time decreases in Sandhoff mice with the progression of disease T1 relaxation time is short in Sandhoff mice as compared to their age-matched controls. No significant differences in the magnetization transfer ratios (MTRs) between control and Sandhoff mice. Significant increase in the cerebral blood flow (CBF) in the terminal stage Sandhoff mice as compared to controls. This increase in the CBF appears to progress with the disease

Conclusions This is the first time MRI study of Sandhoff mouse brain, and only limited data is available from clinical studies. These findings may have applications for disease diagnosis and therapy monitoring by non-invasive MRI methods.

Acknowledgements Members of 1 st. Floor Mr David Smith Dr M. Jeyakumar Dr David Neville Dr Terry Butters Prof Raymond Dwek Dr Fran PlattProf Peter Styles Members of ENG Dr Niki Sibson Dr Kerry Broom Dr John Lowe Dr AM Blamire Dr Justin Smith Mr Andre Thomas Mr Phillip Bradford (Members of BSU) Experimental Neuroimaging Group (ENG), University Lab. of Physiology