Transcript Cystic Fibrosis:

Cystic Fibrosis:
Using ferrets as a Disease Model
Ferret Models
Terms and Abbreviations
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CF = Cystic Fibrosis
SCNT = Somatic Cell Nuclear Transfer
MI = Meconium Ileus
LFT = Liver Function Test
ALT = Alanine Aminotransferase
UDCA = Ursodeoxycholic Acid
FABPi = Fatty acid binding promoter
Background
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CF affects:
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1 in 3,500 newborns each year
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People of mixed European descent
Caused by a defective CFTR gene
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Codes for epithelial chloride channel
Background
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CF affects many tissues:
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Lung
Liver
Pancreas
Male Reproductive Tract
Intestines
Gall Bladder
Sweat Gland
Why ferrets?
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2 reasons:
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Their lung anatomy and cell biology are
similar to humans
They reproduce fast
Methodology
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Knockout gene was engineered
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HA-tagged cDNA of CFTR gene
Used the FABPi promoter
Results
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9 clones heterozygous for CFTR were
bred
Expected 1:2:1 ratio to create ferret
models with CF, or kits
Results
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At 24 hours, CF kits were
indestinguishable from littermates
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At 36 hours, they failed to thrive
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Euthanized at 48 hours
Results: MI Variable
Penetrance
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MI affects the intestine
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It is a blockage
Can cause perforations in intestine
Frequency ranged for 50-100% in
offspring of 9 heterzygous male parents
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Was statistically linked to the parents used
in breeding (P< 0.047)
Results: Male RT
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Nearly all males with CF suffered from
infertility
Vas Deferens becomes absent
throughout development
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Unilateral degeneration detected as early
as 2 yrs old
Results: Male RT
Results: Pancreas
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All glands exhibited legions
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Ferrets were consistant with those in
newborn humans with CF
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Significantly less severe than those seen on the
Pig model
Histopathology of gall bladder and liver
indistinguishable from non CF
littermates
Results: Lungs
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Those infants that escaped MI did not
escape Lung complications
25% of neonatal deaths were not found
out for those who passed MI
Evidence found of pneumonia and
aspiration
Results: Lungs
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ALT levels were elevated
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Bilirubin Elevated
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Cholesterol levels reduced
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Suggests potential liver disease
No histo legions on liver, but elevated LFTs
Results: Liver
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Elevated LFTs is unclear
Bile acid malabsorption by intestine
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Changes circulation and composition of bile
acids
Cholesterol levels low due to defective
fatty acid absorption in the gut
Oral doses of UDCA showed
normalization of LFTs and ALT levels
Results: Nutrition
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Due to bad bile acids, lipids become hard to
digest in CF patients.
Due to impaired pancreas activity, HCO3- is
not secreted into gut which lowers pH
To counteract, oral proton pump is given to
try and normalize gut pH
Conclusions
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There are many models out there
Each one may be best suited to a
specific symptom of CF
Still doing research on ferrets for lungs
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Initial reasoning for using them is sound
References
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1.) Disease phenotype of a ferret CFTR-knockout model of cystic
fibrosis Published in Volume 120, Issue 9 (September 1, 2010)
J Clin Invest. 2010;120(9):3149–3160. doi:10.1172/JCI43052.
Copyright © 2010, American Society for Clinical Investigation
2.) Riordan JR, et al. Identification of the cystic fibrosis gene: cloning and
characterization of complementary DNA. Science. 1989;245(4922):1066–1073
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3.) Egan ME. How useful are cystic fibrosis mouse models? Drug Discov Today
Dis Models. 2009;6(2):35–41.
4.) Rogers CS, et al. Disruption of the CFTR gene produces a model of
cystic fibrosis in newborn pigs. Science. 2008;321(5897):1837–1841.
All 3 Models
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