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Blood component used in medicine can be grown in rice

You can’t get blood from a stone, but apparently you can get it from … rice? It may sound like a spooky Halloween story, but this is actual science coming out of labs in China (where scientists are collaborating with colleagues in Canada and the U.S.).

The thing they’re making isn’t blood itself but a particular component called human serum albumin, or HSA for short. This is a protein that helps transport certain hormones, steroids and fatty acids in the bloodstream.

People make it in their livers, but sometimes they need extra. HSA is used to treat people in hemorrhagic shock, patients with serious burns and other medical conditions. And there’s hope that the protein can be put to use in other ways, such as delivering drugs or oxygen within the body. All told, worldwide demand for HSA tops 500 tons per year.

That’s more than can be easily produced the old-fashioned way -- harvesting the protein from human plasma, the liquid component of blood. In China, demand for HSA was so high that some unscrupulous producers put fake albumin on the market. Hence the desire to make the protein another way.

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Scientists have tried to grow the protein in potato plants and tobacco leaves. Since other human proteins have been grown successfully in rice, the Chinese scientists tried to grow HSA in a species called Oryza sativa. They used a bacteria to deliver the gene for making HSA into the rice plants. After a few generations of breeding, the plants were making HSA pretty reliably, the researchers reported onlineMonday in Procedings of the National Academy of Science.

The research team (based mainly in Wuhan, China) ran several tests to compare the rice and human versions of HSA. Both types had the same molecular mass, amino acid sequence and overall shape, among other similarities. Both versions were able to bind to the blood-thinning drug warfarin and to the painkiller naproxen. In rats with liver cirrhosis, the rice-derived HSA helped the animals eliminate excess abdominal fluid, according to the PNAS report.

The researchers also said they were able to extract the protein from rice in an efficient manner. Their two-day purification process captured about 46% of the protein in the plant, resulting in a yield of 2.75 grams of HSA from every kilogram of brown rice. That’s way more than enough to make commercial production feasible, they said.


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