Welfare of Genetically Modified Mice

Transcription

1 Welfare of Genetically Modified Mice

2 Garvan Institute of Medical Research Immunology diseases Neurological diseases Metabolic diseases Musculoskeletal diseases Cancer

3 My perspective Veterinarian specialising in laboratory animal medicine Director animal facilities Member of the Animal Ethics Committee (AEC)

4 Species used in research Garvan Institute % Use of each species 100% 80% 60% 40% 20% 0% % Use

5 % of genetically modified mice Garvan Institute Mouse Usage 2011 Standard strains GM lines Model for human disease Used to study disease pathway Host for human tumours 26% 74%

6 Australian legal framework National code of practice State based legislation NSW Animal Research Act 1985

7 Structure of Animal Ethics Committee (AEC) Category A - Veterinarian Category B - Scientist Category C Animal Welfare Organisation Representative Category D Community Representative Category E Animal Facility Manager (optional)

8 Components of protocol- justification for animal use Scientific justification for the research Detail & justification for number of animals to be used

9 What is the impact on the animal? Exact detail of type & no. of procedures How is impact on animals minimised?

10 How will be animals be monitored? Frequency animals are checked What criteria are used to assess welfare?

11 What are the end- points When do the animals leave the study or are euthanized?

12 Special protocol conditions GM animals List of lines & phenotypes to be used Phenotype reports on new lines Monitor breeding for overproduction

13 Welfare concerns for GM mice A. Impact of modification on well being & breeding B. Large numbers used in generation of new lines C. Increased number needed in breeding

14 A. Impact of GM modification on well- being Our facility > 500 different GM mouse lines About 25% of lines develop a clinical phenotype spontaneously

15 Breeding strategies to manage lines with phenotype Homozygous lethal Background strain severity Heterozygous x heterozygous pairs OR Each new backcross is a new line and must be monitored closely for phenotype Heterozygous x wild type pairs

16 Conditional knockouts Crossing a cre-line to a floxed line - lox P sites flank the gene of interest Tissue specific cre lines will only knockout the gene in target tissue Minimises impact on animal

17 Workings of a conditional

18 Example conditional B6.Cg-Tg(Alb-cre)21Mgn/J Liver specific expression of cre from an albumin promoter. Gene is only inactivated in the liver

19 Inducible knockouts- inducible promoters Genetic modification is induced by treatment eg tamoxifen or doxycycline Genetic modification can be turned on & turned off

20 How can animal care staff help? Teach staff about lines with phenotype Provide monitoring & end points- cull to reduce suffering Nursing care can minimise impact

21 Example 1- Musculodystrophy model Juvenile musculodystrophy phenotype diminishes with age WT Mate at 12 wks ( normal 7-8 wks) Ac1 Provide soft feed on cage floor for 2 weeks post weaning

22 Example 2- Prostate tumor model Technicians palpate for prostate tumors at every cage change Mice with tumors are sent for research or culled

23 How can database help? Phenotype printed on every card 11/09 JK Diabetes JF NOD.Iggtg Instructions for technician viewable on database 3 females DOB 4/04/ Iggtg/Iggtg 2565 Iggtg/Iggtg 2566 Iggtg/Iggtg IIIIIIIIIIIIIIIIIIIIII

24 Interaction of phenotype & experiment Experimental procedure may interact adversely with phenotype Cause of illness or deaths must be investigated

25 Example- NODscidIL2KO Mice with scid mutation are very susceptible to total body irradiation Dose must be reduced < 300rads

26 B. Large numbers used in generation of new lines Improved techniques minimises numbers/line BUT LARGE NUMBERS LINES ARE BEING MADE

27 Improve welfare during line development Use of analgesics Use of optimal anaesthetics Develop culture of continual improvement

28 C. Increased number needed in breeding- why? Unwanted genotypes Breeding to make lines with multiple gene modifications Lines with adverse phenotype may require extra breeders More than one researcher keeps the same line

29 How to minimise numbers used in breeding Cryopreserve lines not in use Plan breeding well Train technicians Good administration of facilities

30 Cryopreservation Maintenance breeding commonly wastes 100 mice/ line/ year Offer choice eg. sperm & embryo freezing

31 Plan the breeding Homozygous pairs no unwanted genotypes Lines heterozygous for multiple genes can replace breeding of multiple lines Backcross minimise litters at every generation AND use speed congenics

32 Trained technicians Remove poor breeders Recognise when delayed weaning is needed Contact researcher if too many pairs are breeding

33 Good administrative measures Keep accurate live records Introduce cost recovery Efficient communication between technicians and researchers

34 Thanks for your attention