Transgenic animals

Definition

A transgenic animal is one whose genome has been altered by the transfer of a gene or genes from another species or breed.

The photo shows two transgenic mice positioned either side of a plain mouse. The transgenic mice have been genetically modified so that they carry a green fluorescent protein which glows green under blue light. Credit: Ingrid Moen et alet al., BMC Cancer, 12/21 (2012), 1-10.

Importance

Transgenic animals are routinely used in the laboratory as models in biomedical research. Over 95 per cent of those used are genetically modified rodents, predominantly mice. They are important tools for researching human disease, being used to understand gene function in the context of disease susceptibility, progression and to determine responses to a therapeutic intervention. Mice have also been genetically modified to naturally produce human antibodies for use as therapeutics. Seven out of the eleven monoclonal antibody drugs approved by the FDA between 2006 and 2011 were derived from transgenic mice. Transgenic farm animals are also being explored as a means to produce large quantities of complex human proteins for the treatment of human disease. Such therapeutic proteins are currently produced in mammalian cell-based reactors, but this production process is expensive. In 2008, for example, the building of a new cell-based manufacturing facility for one therapeutic protein was estimated to cost over US$500 million. A cheaper option would be to develop a means to produce recombinant proteins in the milk, blood or eggs of transgenic animals. Progress in this area, however, has been slow to-date. Only two biomedical products have so far received regulatory approval. The first is human antithrombin III, a therapeutic protein produced in the milk of transgenic goats, which is used to prevent clots in patients with hereditary antithrombin deficiency receiving surgery or undergoing childbirth. A relatively small herd of goats (about 80) can supply enough human antithrombin III for all of Europe. The second product is a recombinant human C12 esterase inhibitior produced in the milk of transgenic rabbits. This is used to treat hereditary angiodema, a rare genetic disorder which causes blood vessels in the blood to expand and cause skin swellings.

Discovery

The ability to produce transgenic animals is reliant on a number of components. One of the first things needed to generate transgenic animals is the ability to transfer embryos. The first successful transfer of embryos was achieved by Walter Heape in Angora rabbits in 1891. Another important component is the ability to manipulate the embryo. In vitro manipulation of embryos in mice was first reported in the 1940s using a culture system. What is also vital is the ability to manipulate eggs. This was made possible through the efforts of Ralph Brinster, attached to the University of Pennsylvania, who in 1963 devised a reliable system to culture eggs, and that of Teh Ping Lin, based at the California School of Medicine, who in 1966 outlined a technique to micro-inject fertilised mouse eggs which enabled the accurate insertion of foreign DNA. The first genetic modification of animals was reported in 1974 by the virologist Rudolph Jaenisch, then at the Salk Institute, and the mouse embryologist Beatrice Mintz at Fox Chase Cancer Center. They demonstrated the feasibility of modifying genes in mice by injecting the SV40 virus into early-stage mouse embryos. The resulting mice carried the modified gene in all their tissues. In 1976, Jaenisch reported that the Moloney Murine Leukemia Virus could also be passed on to offspring by infecting an embryo. Four years later, in 1980, Jon Gordon and George Scango together with Frank Ruddle, announced the birth of a mouse born with genetic material they had inserted into newly fertilised mouse eggs. By 1981 other scientists had reported the successful implantation of foreign DNA into mice, thereby altering the genetic make-up of the animals. This included Mintz with Tim Stewart and Erwin Wagner at the Fox Chase Cancer Center in Philadelphia; Brinster and Richard Palmiter at the University of Washington, Seattle; and Frank Costantini and Elizabeth Lacy at Oxford University. Such work laid the basis for the creation of transgenic mice genetically modified to inherit particular forms of cancer. These mice were generated as a laboratory tool to better understand the onset and progression of cancer. The advantage of such mice is that they provide a model which closely mimics the human body. Such mice are not only used to gain greater insight into cancer but also to test experimental drugs.

Application

Since the mid-1980s transgenic mice have become a key model for investigating disease. Mice are the model of choice not only because there is extensive analysis of its completed genome sequence, but its genome is similar to the human. Moreover, physiologic and behavioural tests performed on mice can be extrapolated directly to human disease. Robust and sophisticated techniques are also easily available for the generic manipulation of mouse cells and embryos. Another advantage of mice is the fact that they have a short reproduction cycle. Other transgenic species, such as pig, sheep and rats are also used, but their use in pharmaceutical research has so far been limited due to technical constraints. Recent technological advances, however, are laying the foundation for wider adoption of the transgenic rat.

Transgenic rodents play a number of critical roles in drug discovery and development. Importantly, they enable scientists to study the function of specific genes at the level of the whole organism which has enhanced the study of physiology and disease biology and facilitated the identification of new drug targets. Due to their similarity in physiology and gene function between humans and rodents, transgenic rodents can be developed to mimic human disease. Indeed, an array of transgenic mice models have been produced for this purpose. Mice are being used as models, for example, to study obesity, heart disease, diabetes, arthritis, substance abuse, anxiety, ageing, Alzheimer's disease and Parkinson's disease. They are also used to study different forms of cancer. In addition, transgenic pigs are being investigated as a source of organs for transplants, which if proven clinically safe could overcome some of the severe donor organ shortages. The development of transgenic animnals has recently been transformed by the emergence of the new gene editing tool CRISPR which greatly reduced the number of steps involved in the creation of transgenic animals, making the whole process much faster and less costly.


This section on transgenic mice was jointly written by Lara Marks and Dmitriy Myelnikov. For more information see D. Myelnikov, 'Transforming mice: technique and communication in the making of transgenic animals, 1974-1988', unpublished PhD, Cambridge University, 2015.

Transgenic animals: timeline of key events

Founded by Clarence Little, one of the leading researchers into genetic differences governing the rejection of foreign tissues. 1929-01-01T00:00:00+00001974-01-01T00:00:00+0000Gordon, J W, Scangos, G A, Plotkin, D J, Barbosa, J A, Ruddle, F H, 'Genetic transformation of mouse embryos by microinjection of purified DNA', PNAS USA 77 (1980), 7380–4.1980-09-01T00:00:00+0000M Capecchi, 'High efficiency transformation by direct microinjection of DNA into cultured mammalian cells', Cell, 22/2 (1980), 479-88.1980-11-01T00:00:00+0000Costantini, F, Lacy, E, 'Introduction of a rabbit b-globin gene into the mouse germ line', Nature, 294 (1981), 92–4.1981-11-05T00:00:00+00001982-12-01T00:00:00+0000The course is started at Cold Harbour Laboratory together with collaborators from other centres.1983-01-01T00:00:00+0000These are created with the objective of studying self-tolerance. 1985-01-01T00:00:00+0000Capecchi, M, 'Site-directed mutagenesis by gene targeting in mouse embyo-derived stem cells', Cell, 51/3 (1987), 503-12.1987-11-06T00:00:00+0000This patent is filed on the basis of work reported in M Brüggeman, HM Caskey, C Teale, H Waldmann, Williams, Surani, and MS Neuberger, A repertoire of monoclonal antibodies with human heavy chains from transgenic mice, Proc Natl Acad Sci USA, 86 (Sept 1989), 6709-13. 1988-01-01T00:00:00+0000USPTO patent 4,736,866, transgenic mouse with activated oncogenes created by Philip Leder and Timonthy A Stewart. The mouse was developed as a model for furthering cancer research and the testing of new drugs. It was the first animal ever given patent protection in the USA. 1988-04-12T00:00:00+0000Mouse genetated with genes knocked out that produce the enzyme DNA methyltransfgerase involved in DNA methylation. E. Li, T.H. Bestor, R. Jaenisch, 'Targeted mutation of the DNA methyltransferase gene results in embryonic lethality', Cell, 69/6 (1992), 915-26.1992-06-12T00:00:00+0000Three groups of scientists separately report the successful generation of different strains of transgenic mice for the generation of human monoclonal antibodies. Two of the teams are based in biotechnology companies: GenPharm (led by Nils Lonsberg), Cell Gensys (led by Larry Green) , and the other involved a collaboration (led by Marian Bruggemann and Michael Neuberger) between scientists at the Laboratory of Molecular Biology, Braham Institute and the University of Cologne.1994-01-01T00:00:00+0000Dolly the sheep was born as a result of the cloning of an adult cell. This was achieved by transferring the nucleus of an adult sheep's cell to the nucleus of an unfertilised egg cell. It took 277 attempts to achieve success.1996-01-07T00:00:00+0000Dolly the sheep was created by cloning an adult cell. This was done by transferring the nucleus of an adult sheep's cell to the nucleus of an unfertilised egg cell. It took 277 attempts to achieve success.1996-07-05T00:00:00+0000Dolly the sheep was created by cloning an adult cell. This was done by transferring the nucleus of an adult sheep's cell to the nucleus of an unfertilised egg cell. It took 277 attempts to achieve success.2003-02-14T00:00:00+0000Panitumumab (Vectibix) was approved by the FDA for the treatment of patients with EGFR-expressing metatastic colorectal cancer. The drug is a fully human monoclonal antibody created with transgenic mice. It was developed by Agensys with Amgen. 2006-09-27T00:00:00+0000Awarded to to Mario Capecchi, Martin Evans and Oliver Smithies. Their work made it possible to modify specoific genes in the germline of mammals which could produce offspring that carried and expressed the modified gene. Their method is commonly called knockout technology. This has given scientists the means to study the role of specific genes in development, physiology and pathology. 2007-01-01T00:00:00+0000The pigs, a small breed known as Bama, have had some genes disabled. They are being used for studying stem cells, gut microbiota, and Laron syndome, a type of dwarfism caused by a mutation in the human GHR gene. 2015-09-23T00:00:00+0000Work presented by geneticist George Church of Harvard Medical School to US National Academy of Sciences.2015-10-05T00:00:00+0000Collaborative research carried out by scientists at University of Edinburgh, University College London and Imperial College. 2017-04-20T00:00:00+0000
Date Event People Places
1929Jackson Memorial Laboratories established to develop inbred strains of mice to study the genetics of cancer and other diseasesJackson Memorial Laboratoroies
1974First publication on inserting foreign DNA into miceJaenisch, MintzSalk Institute, Fox Chase Institute for Cancer Research
September 1980First transgenic mice made with recombinant DNA announced Barbosa, Gordon, Plotkin, Ruddle, ScangosYale University
November 1980Technique published using fine glass micropipettes to inject DNA directly into the nuclei of cultured mammalian cells. High efficiency of the method enables investigators to generate transgenic mice containing random insertions of exogenous DNA. CapecchiUniversity of Utah
5 Nov 1981First report of successful nuclear integration and germ-line transmission of foreign DNA into laboratory miceConstantini, LacyOxford University, Yale University
December 1982Giant mice made with the injection of rat growth hormoneBrinster, PalmiterUniversity of Pennsylvania, University of Washington Seattle
1983Course started in the molecular embyology of miceCostantini, Hogan, Lacy Cold Spring Harbour Laboratory, NIMR, Sloan Kettering Cancer Research Center, Columbia University
1985First transgenic mice created with with genes coding for both the heavy and light chain domains in an antibody.Kohler, RusconiMax-Planck Institute
6 Nov 1987Publication of gene targeting technique for targetting mutations in any geneThomas, CapecchiUniversity of Utah
1988Patent application filed for a method to create transgenic mice for the production of human antibodiesBruggeman, Caskey, Neuberger, Surani, Teale, Waldmann, WilliamsLaboratory of Molecular Biology, Babraham Institute, Cambridge University
April 1988OncoMouse patent grantedLeder, StewartHarvard University
12 Jun 1992First transgenic mouse model created for studying link between DNA methylation and diseaseLi, Bestor, JaenischWhitehead Institute for Biomedical Research
1994First transgenic mice strains reported for producing human monoclonal antibodiesBruggemann, Green, Lonsberg, NeubergerCell Genesys, GenPharm, Laboratory of Molecular Biology
January 1996First cloning of a mammalWilmutRoslin Institute
5 Jul 1996Dolly the sheep, the first cloned mammal, was bornWilmutRoslin Institute
14 Feb 2003Dolly the sheep, the first cloned mammal diedWilmutRoslin Institute
September 2006First fully human monoclonal antibody drug approvedAgensys, Amgen
2007Nobel Prize for Physiology for Medicine awarded for their discoveries enabling germline gene modification in mice by the use of embryonic stem cellsCapecchi, Evans, SmithiesUniversity of North Carolina, University of Utah
23 Sep 2015Beijing Genomics Institute announced the sale of the first micropigs created with the help of the TALENs gene-editing technique at Shenzhen International Biotech Leaders SummitBeijing Genomics Institute
5 Oct 2015US Scientists report use of CRISPR to modify 60 genes in pig embryos in first step to create pig organs suitable for use in humansChurchHarvard University
20 Apr 2017Diabetes research using transgenic mice shows the protein P2X7R plays important role in inflammation and immune system offering new avenue for treating kidney diseaseMenziesUniversity of Edinburgh, University College London, Imperial College

1929

Jackson Memorial Laboratories established to develop inbred strains of mice to study the genetics of cancer and other diseases

1974

First publication on inserting foreign DNA into mice

Sep 1980

First transgenic mice made with recombinant DNA announced

Nov 1980

Technique published using fine glass micropipettes to inject DNA directly into the nuclei of cultured mammalian cells. High efficiency of the method enables investigators to generate transgenic mice containing random insertions of exogenous DNA.

5 Nov 1981

First report of successful nuclear integration and germ-line transmission of foreign DNA into laboratory mice

Dec 1982

Giant mice made with the injection of rat growth hormone

1983

Course started in the molecular embyology of mice

1985

First transgenic mice created with with genes coding for both the heavy and light chain domains in an antibody.

6 Nov 1987

Publication of gene targeting technique for targetting mutations in any gene

1988

Patent application filed for a method to create transgenic mice for the production of human antibodies

Apr 1988

OncoMouse patent granted

12 Jun 1992

First transgenic mouse model created for studying link between DNA methylation and disease

1994

First transgenic mice strains reported for producing human monoclonal antibodies

Jan 1996

First cloning of a mammal

5 Jul 1996

Dolly the sheep, the first cloned mammal, was born

14 Feb 2003

Dolly the sheep, the first cloned mammal died

Sep 2006

First fully human monoclonal antibody drug approved

2007

Nobel Prize for Physiology for Medicine awarded for their discoveries enabling germline gene modification in mice by the use of embryonic stem cells

23 Sep 2015

Beijing Genomics Institute announced the sale of the first micropigs created with the help of the TALENs gene-editing technique at Shenzhen International Biotech Leaders Summit

5 Oct 2015

US Scientists report use of CRISPR to modify 60 genes in pig embryos in first step to create pig organs suitable for use in humans

20 Apr 2017

Diabetes research using transgenic mice shows the protein P2X7R plays important role in inflammation and immune system offering new avenue for treating kidney disease