Brussels, 29 Mar 2006
Human Serum Albumin (HSA) is a component of blood plasma essential for maintaining blood pressure and transporting minerals and hormones. Current worldwide demand for HSA exceeds 500 tons per year - almost all derived from blood donations - and is essential for surgery, dehydration, liver or kidney disease or haemorrhages. A new Spanish study suggests that a synthetic HSA could be manufactured from tobacco plants.
The new technique is the result of a PhD thesis by Alicia Fernàndez San Millàn from the Universidad Pública Navarra, and could provide a cheap GM alternative to HSA from blood plasma.
As commercial stocks of blood plasma do not generally meet demand, there has been a drive to manufacture HSA from yeast cells, mammal cells or vegetables. The costs to produce HSA from these sources is high -300 to 4,000 euro per gram, compared to 4 euro per gram from blood plasma.
The new technique, nuclear transformation, yields 14 times the HSA (this translates to 0.9 mg) per gram of fresh tobacco leaf. The reason why the level of albumin is so high is that the gene sequence is spliced to the chloroplast genome, effectively the plant's factory. This in turn causes the plant to churn out large quantities of albumin.
Another advantage to the process is that transmission of the GM crops will be limited, as the chloroplast genome is inherited maternally, so there would be no genetic escape through pollen.
Tobacco has been cultivated commercially for several hundred years, and is able to produce a large quantity of biomass. 'Given that the protein is produced in the chloroplasts, the more leaf biomass we have, the more albumin we can get,' said San Millàn. The next step will be to develop commercial trials of albumin-producing tobacco. While cheap synthetic albumin may be some years away, this process could be the route to it.