- The first commercial therapeutic recombinant protein produced using mammalian cells was recombinant human tissue plasminogen activator (tPA), which was approved by the U.S. FDA in 1987 under the brand name Activase. Developed by Genentech, tPA is used to dissolve blood clots in patients suffering from acute myocardial infarction (heart attacks), and later found use in stroke treatment as well.
- Unlike earlier recombinant proteins such as insulin or growth hormone, which could be effectively produced in bacterial systems like E. coli, tPA required a more complex production environment. Specifically, it needed post-translational modifications such as glycosylation to function correctly—something bacterial systems are incapable of performing. To address this, scientists used Chinese hamster ovary (CHO) cells, a type of mammalian cell line capable of carrying out human-like protein folding and glycosylation.
- The successful development and commercialization of tPA marked a turning point in recombinant protein technology. It demonstrated the feasibility and therapeutic value of using mammalian cell expression systems for producing biologically active, complex human proteins. This paved the way for a new generation of biopharmaceuticals, especially those involving monoclonal antibodies, clotting factors, and other glycoproteins requiring sophisticated cellular machinery.
