Cows Bred to Produce Potential Anti-Tumor Protein
The protein is itself a lab creation called r28M, a two-way antibody designed to lock on to both melanoma cells and a type of tumor-killing immune cell.
Such complex proteins are difficult to generate from bacterial cell systems, Dr. Gottfried Brem, at the University of Veterinary Medicine in Vienna, Austria, and colleagues note. Even though they can be produced in mammalian cell culture, this approach is costly, laborious, and produces only small yields.
According to their report in Proceedings of the National Academy of Sciences, therapeutic proteins, such as clotting factors for treating hemophilia, can be harvested from the blood of mammals. They theorized that a similar approach could be used to manufacture r28M.
The researchers inserted the gene for r28M into early-stage bovine embryos, which were then were implanted into cows. Out of 77 transfers into 31 recipients, there were 13 pregnancies and 11 calves were born alive and healthy.
According to the report, the protein was isolated from the animals' blood at increasing concentrations during the first 9 months after they were born.
Incubation of the antibody with human immune cells and melanoma cells resulted in a strong increase in the number of tumor-killing cells.
"Having established a successful 'gene farming' procedure for the r28M protein, it should now be possible to evaluate its therapeutic potential in experimental clinical trials," Brem's group writes.