Scientists have found a way to use maize to produce an expensive drug. Specifically, it’s a drug for a rare and life-threatening lysosomal disease that could previously only be manufactured by expensive cell culture techniques.
People who have this inherited disease endure progressive damage to the heart, brain, and other organs, which if left untreated, results in death in early childhood.
Right now, the enzyme used to treat it can only be made by culturing mammalian cells – they’re the only ones capable of performing the biochemical tweaks required to make the enzyme function. The enzyme-replacement therapy costs $300,000 to $500,000 per year for children and much higher for adults.
To help decrease the costs, a team led by Allison Kermode at Simon Fraser University in Burnaby, Canada, turned to transgenic, greenhouse-grown maize.
Actually, they tricked the maize into making certain modifications.
And that’s because when human proteins are expressed in plant cells, they’re usually decorated with plant-specific sugar molecules, which could prompt a dangerous immune reaction if injected into patients, Nature explains.
The team tweaked the protein-producing genes, not to alter the sequence of the human protein, but to ensure that, once made, the proteins would not be moved through the cell's Golgi complex, a structure where the problematic sugars are added. The engineered maize seeds produced proteins decorated with sugars that could be converted to human forms.
In the end, they were able to synthesize alpha-L-iduronidase, the enzyme used to treat the rare lysosomal storage disease mucopolysaccharidosis I.
Other plants are already being used to make biopharmaceuticals. In May, the US Food and Drug Administration approved the first ever drug produced in a genetically engineered plant cell: Elelyso for the lysosomal storage disorder Gaucher disease, produced in carrot cells. Drugs made in duckweed, safflower, and tobacco have progressed as far as clinical trials – but their sugar patterns have been problematic too.
If all goes well, however, maize may one day become the go-to way to make complex protein drugs.
The work was published in Nature Communications this week.
[Via Nature News]
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