Blood proteins probably make you think of animals, not plants, but plant science has found a way to produce human serum albumin (HSA) in rice. A team lead by ASPB member Daichang Yang at Wuhan University in China has published their advance in the Proceedings of the National Academy of Sciences this week; the paper was also featured in a news article in The Scientist.

HSA is used in treating severe blood loss, burn injuries, and liver disease among other conditions as well as in commercial applications as an additive to cell culture media, a carrier for active compounds in medications, and in vaccine production. HSA is typically isolated from human plasma, the liquid portion of blood, where it is the most abundant protein. However, blood donors can be in short supply and there exists a theoretical risk of contracting bloodborne infectious diseases such as HIV/AIDS and hepatitis—a risk that can be eliminated by production of the protein in plants. Researchers are also able to circumvent several issues surrounding typical recombinant protein production schemes from microbial contamination to yield using rice to produce HSA in an economical manner. As the global demand for HSA exceeds 500 tons per year, an additional source of the pure protein would be welcomed.

Yang He and colleagues utilized a natural protein storage organ, the endosperm located within the rice grain, where they obtained approximately 10% of total soluble protein as HSA. Important for the future commercialization of rice HSA, the structure, function, and immunogenicity of the rice-produced protein are equivalent to plasma isolated HSA. While everything is on track for commercialization of rice HSA, several regulatory hurdles, from growing genetically engineered plants to clinical trials, must be cleared.

In the meantime, kudos to He and colleagues for blurring the boundaries between plant science and biomedical research.

Citation: Yang He, Tingting Ning, Tingting Xie, Qingchuan Qiu, Liping Zhang, Yunfang Sun, Daiming Jiang, Kai Fu, Fei Yin, Wenjing Zhang, Lang Shen, Hui Wang, Jianjun Li, Qishan Lin, Yunxia Sun, Hongzhen Li, Yingguo Zho, and Diachang Yang. (2011). Large-scale production of functional human serum albumin from transgenic rice seeds. Proceedings of the National Academy of Sciences, 10.1073/pnas.1109736108.

· Ruth Williams. "Blood Protein from Rice.” The Scientist, October 31, 2011.