Contained molecular farming using plant cell and tissue cultures

Plant cell suspension cultures grow in a liquid medium as individual cells or small aggregates, and are usually derived from callus tissue by the disaggregation of friable callus pieces in shake flasks. Recombinant proteins produced by sterile cultures of plant cells and tissues can be secreted into the medium if an N-terminal signal peptide is used to direct the protein into the secretory pathway. The first approved veterinary and pharmaceutical proteins produced by molecular farming were manufactured using cell suspension cultures. This required several technical, regulatory, and commercial barriers to be addressed. The principal technical barriers were the low specific productivity, low recovery, and variable quality associated with plant-derived pharmaceuticals. The quality and consistency of recombinant proteins produced in plant cells depends on two types of processing, namely the processing associated with protein synthesis and activity, and the processing associated with protein damage and degradation.