Scientists in London are using plants as factories for the production of novel, pharmaceutically useful molecules. Plants harness energy from sunlight and convert it into sugars, a process essential to our life on Earth. These sugars, and the many other molecules plants make; we eat or feed to livestock. Plants also naturally produce a number of medicinal molecules, such as aspirin. Therefore, we have long been aware that plants are capable of producing complex and useful molecules in large quantities and we have exploited this, predominately through farming.
Work in a number of laboratory’s, including Professor Julian Ma’s at St. Georges Hospital in London utilises the power of plants to make molecules. But these are molecules not naturally produced by plants. Plants can be engineered to express proteins from other species which are then called recombinant proteins, and they include proteins such as human antibodies which are required for vaccination. In particular, Professor Ma’s group use plants to produce an antibody against HIV, the virus that leads to AIDS. Just as we farm plants for molecules to eat they can now farm plants for specific pharmaceutical molecules, this technique has been termed “pharming”.
Plants offer a number of advantages over other systems used to produce recombinant proteins. Traditionally bacteria and yeast cells have been used but these both require very sterile conditions for growth, which are expensive to maintain, and the quantities are limited. Also mammalian cell lines have been used, but again growth conditions have to be closely regulated and contamination can cause the loss of a huge quantity of cells and as such the final product. Plants on the other hand, are grown in greenhouses and the end product is of extremely high quality – better than any of the other systems. The development of this technology offers huge potential, the efficient and reliable production of recombinant proteins, which can then be used to treat and prevent diseases. The work in Professor Ma’s group focuses on diseases most prevalent in developing countries including HIV, tuberculosis and rabies. So far they have developed and refined the expression of antibodies in plants. They also work on the characterisation of the pharmacological candidates for testing in human trials.
As the technology developed in Professor Ma’s laboratory uses genetic modification they have been careful to use plants that will not enter the food chain. The ideal plant produces a large amount of seeds, which are packed with protein, in the case of Professor Ma’s plants recombinant proteins such as antibodies against HIV. Currently they are using tobacco plants as a lot is known about farming them, which can be utilised for biological pharming. Whilst this technology is still in its trial stages, data so far has shown it has huge potential in the production of large quantities of high quality recombinant proteins. Pharming may indeed be the way forward.
T. Barbi, S.L.Irons, I. Pepponi, C. Hawes, J. K-C. Ma and P. M.W. Drake (2010). Expression and plasma membrane localization of the mammalian B-cell receptorcomplex in transgenic Nicotiana tabacum. Plant Biotechnology Journal 1-11