By Chris Healey
Pharmaceutical production using plants has been in the spotlight after Mapp Pharmaceutical revealed its experimental Ebola serum ZMapp—credited with saving the lives of two Americans—was created using antibodies harvested from genetically-modified tobacco plants.
ZMapp is part of a growing trend of pharmaceuticals created from proteins produced in plants, a practice considered safer, cheaper, and more practical than common production methods.
There has been outcry about claims ZMapp will not be sent to Africa to combat the ongoing Ebola epidemic. Those claims come after the pharmaceutical industry has been slow to adopt plant production methods, despite cost-effectiveness relative to traditional production methods.
Large pharmaceutical powerhouses, such as Pfizer and Merck, have adhered to traditional production methods despite newer and cheaper techniques. However, smaller companies, such as Mapp Pharmaceutical and IBio, have taken advantage of the low cost of plant production to produce their pharmaceutical ingredients.
Transgenic techniques allow scientists to hijack existing cellular processes in plants to produce desired proteins, such as enzymes and antibodies. DNA instructions for a desired protein (also called a gene) can be created in laboratory settings and inserted into a plant cell nucleus. After insertion, the gene instructs the cells how to make the desired proteins.
Once the proteins are produced, scientists can harvest them for use in pharmaceuticals. Transgenic techniques can be repeated and scaled to fit need. There are two methods commonly used to insert genes into plants.
One widely-used transgenic technique involves Agrobacterium tumefaciens bacteria as a gene transportation medium. Scientists introduce a gene into bacteria prior to plant inoculation. Bacteria then release desired DNA into plant cell nuclei and gene expression proceeds normally.
An alternative method, called biolistic transformation, involves the use of a gene gun to launch desired genes at clusters of plant cells. Some of the clusters will land inside cell nuclei, where the introduced DNA will integrate with the plant’s genome for expression.
Regardless of technique, using plants to create proteins eliminates the threat of human pathogen contamination which is possible with animal-derived mediums. Plants and animals do not share common pathogens, so a potential infection present at the time of harvesting will have no effect on protein recipients.
Image Credit: HPR2