Some complex protein drugs need to be made by culturing mammalian cells. Plant biologists have developed a way to manufacture the necessary enzymes for drugs in maize.
The scientists published their findings in the journal Nature Communications. Plant biologist Allison Kermode, at Simon Fraser University in Burnaby, Canada, whose husband works with people who have lysosomal storage disorders, is working on ways to create enzyme-replacement drugs.
When human proteins are expressed in plant cells, they are usually decorated with plant-specific sugar molecules that prompt a dangerous immune reaction in patients. The biologists came up with ways to avoid these problems.
The group tweaked the protein-producing genes to ensure that once the proteins are made, they would not move through the cell’s Golgi complex, the structure through which the problematic sugars are added. The newly engineered maize seeds produce proteins decorated with sugars that can be easily converted to human forms.
Other attempts to solve this problem require mutating the protein, which can disrupt its function, or engineering plants to modify the proteins in a different way, which can be time-consuming and doesn’t always work.
Cereal crops can be grown using established methods, and the seeds themselves are ideal for long-term protein storage. It will take time before these drugs reach clinical trials. Enzymes purified from engineered seeds are functional, but they haven’t been tested in humans. The seeds also have to produce enough proteins.
Reference: “Production of α-L-iduronidase in maize for the potential treatment of a human lysosomal storage disease” by Xu He, Thomas Haselhorst, Mark von Itzstein, Daniel Kolarich, Nicolle H. Packer, Tracey M. Gloster, David J. Vocadlo, Lorne A. Clarke, Yi Qian and Allison R. Kermode, 18 September 2012, Nature Communications.