Experiments have shown that human growth hormone genes can be expressed in mice. Human genes are inserted into mice to study the molecular basis of genetic disorders, such as Alzheimer's disease. A variety of methods is used to introduce genes.
Farm animals may be used to produce TPA for diminishing the severity of heart attacks or CFTR used in the treatment of cystic fibrosis.
Genetically identical cattle embryos can be grown in culture. The embryos can be genetically modified. Experimenters are attempting to create resistance to mad cow disease. Others are attempting to engineer cattle to produce human serum albumin for medical use.
The cloning of animals could lead to disease-resistant types.