Molecular farming in plants: host systems and expression technology.

Plants provide an inexpensive and convenient system for the large-scale production of valuable recombinant proteins. This principle has been demonstrated by the commercial success of several first-generation products, and many others are currently under development. Over the past ten years, several efficient plant-based expression systems have emerged, and >100 recombinant proteins have now been produced in a range of different species. Plants have many advantages over other production systems, particularly in terms of practicality, economy and safety. However, several constraints that hinder the widespread use of plants as bioreactors remain to be addressed. Important factors include quality and homogeneity of the final product, the challenge of processing plant-derived pharmaceutical macromolecules under good manufacturing practice conditions and concerns about biosafety. Molecular farming in plants will only realize its huge potential if these constraints are removed through rigorous and detailed science-based studies.