Most human serum albumin (HSA) for medical applications is derived from human plasma due to the lack of suitable heterologous expression systems for recombinant HSA (rHSA).

To determine whether plant cell cultures could provide an alternative source, Dr. Sun Qiaoyang and his supervisor Prof. Xu Zengfu of Xishuangbanna Tropical Botanical Garden (XTBG) and other colleagues employed the hyper-translatable cowpea mosaic virus protein expression system (CPMV-HT) to stably express rHSA in tobacco Bright Yellow-2 (BY-2) cells.

In the study, a cowpea mosaic virus vector was used to express human serum albumin in plant cells. Recombinant human serum albumin (rHSA) was highly produced in tobacco BY-2 cells. Cultivation of BY-2 cells in pH 8.0 medium improved the yield of rHSA two-fold. A simple purification scheme was developed to purify the rHSA from culture medium. Detailed characterization showed plant cell-derived rHSA was identical to natural HSA.

The researchers have shown that rHSA, which is highly susceptible to protease degradation, can be successfully expressed and purified from the culture medium of tobacco BY-2 cells transformed with a pEAQ-based construct. Considering the fast growth rate of BY-2 cells and the ease of protein purification due to the secretion of recombinant proteins into the culture medium, the combination of the BY-2 cells and pEAQ vector system can be used as an excellent expression system for production of pharmaceutical proteins.

The study entitled “Improved expression and purification of recombinant human serum albumin from transgenic tobacco suspension culture” has been published online in Journal of Biotechnology, doi:10.1016/j.jbiotec.2011.06.033 .

Abstract http://www.sciencedirect.com/science/article/pii/S0168165611003324