Human proteins are often used in the medical treatment of various human diseases. The most common way to produce proteins is through human cell culture, an expensive approach that rarely results in adequate quantities of the desired protein. Larger amounts of protein can be produced using bacteria or yeast. However, proteins produced in this way lack important post-translational modification steps necessary for protein maturation and proper functioning. Additionally, there are difficulties associated with the purification processes of proteins derived from bacteria and yeast. Scientists can obtain proteins purified from blood but there is always risk of contamination. For these reasons, new ways of obtaining low-cost, high-yield, purified proteins are in demand.

One solution is to use transgenic animals that are genetically engineered to express human proteins. Gene targeting using nuclear transfer is a process that involves removing nuclei from cultured...