The growth in the field of molecular biology and biotechnology is due to the intensive research using transgenic animals. However, there are many ethical issues regarding the use of transgenic animals, because, the genome of transgenic animals is deliberately modified. The first transgenic animals called chimeric mice were created by combining two cells taken from two different embryos of different strains. This gave rise to a single embryo, which was implanted into a surrogate mother to give birth to a chimeric mouse.
Specially designed transgenic animals are used to study gene regulation and effects of genes on the normal functions of the human body and its development. To study the role of insulin in humans, genes from a rabbit or a mouse are introduced into another mouse, which then gives birth to transgenic animals having the altered gene for insulin. Then, the biological effects of the newly introduced gene are studied to obtain information about the role of insulin in the human body.
Transgenic animals are also used for understanding how genes contribute to the development of a disease and thereby help in treatments for diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s disease. Transgenic animals are used to produce expensive biological products such as alpha one antitrypsin used for the treatment of emphysema, at a cheaper rate. Even attempts for treatment of genetic disorders such as phenylketonuria or PKU and cystic fibrosis were made.
The first transgenic cow, Rosie, produced human protein enriched milk containing 2.4 grams of human protein in every litre. This milk contained the human gene alpha-lactalbumin which made it a more nutritionally balanced product than natural cow milk. The transgenic animals are also being used to test the safety of vaccines before using on humans and to test and study the toxicity of chemicals. The creation of transgenic animals has even reduced the overall use of laboratory animals.