Bioreactor has experienced three development stages: bacterial genetic engineering, cell genetic engineering and transgenic animal bioreactor. The emergence of transgenic animal bioreactor has attracted great attention because it overcomes the defects of the first two, that is, the products of cell genetic engineering often have no biological activity, and only after a series of modifications such as glycosylation and hydroxylation can they become effective drugs. However, large-scale production of cell genetic engineering is limited due to the strict requirements for mammalian cell culture conditions and high cost. In addition, the transgenic animal bioreactor has the characteristics of high product quality and easy purification.
Generally, transgenic animals whose target fragments are expressed in organs or tissues are called animal bioreactors. Almost any living organ, tissue or part of it can be domesticated as a bioreactor. From the production point of view, the tissues or organs selected by bioreactor should be convenient for obtaining products, such as breast, bladder, blood and so on. Therefore, animal mammary gland bioreactor, animal blood bioreactor and animal bladder bioreactor have been developed. Among them, the research of transgenic animal mammary gland bioreactor is the most striking.