THE anti-smoking lobby will have to rethink its view of the tobacco plant. French researchers have brought about its rehabilitation by genetically engineering the plant to produce a workable form of artificial human blood.
Concerns about the safety of donated blood have spurred efforts to find an alternative that is guaranteed free of any infection but can still carry oxygen around the body. Work reported in the science journal Nature suggests that a safe replacement might be delivered by the plant that reformed smokers love to hate.
Tobacco is a scientist-friendly plant - despite what it can do if you set it alight - and is frequently used by researchers looking for a compliant subject for genetic modification.
Dr Michael C. Marden and colleagues from the Hospital de Bietre and from Biochem, based at the University of Cezeaux, took a tobacco plant, fused in copies of human DNA sequences and encouraged the plant to grow the blood substitute.
Haemoglobin is the blood protein that holds and carries oxygen and carbon dioxide in the bloodstream and there are two parts to the protein. The researchers took copies of the two DNA sequences that produce the protein and transferred them into tobacco by "piggy-backing" them on a common plant bacterium.
If you can transfer "foreign" DNA into a plant in this way, the plant takes it on as its own and begins producing the protein. The French team succeeded and pure haemoglobin was recovered from the seeds and roots of the plants pressed into human service. Tests showed that the haemoglobin bound oxygen just like the real thing.
While it will be some time before plant-produced haemoglobin is given as a substitute blood product the success is important because it shows that genetically engineered plants could be used to manufacture artificial blood.
Similar substitutes are being derived from out-of-date human or bovine blood, from engineered bacteria and yeasts and from engineered animals. All these, however, allow a risk of cross-infection.
The researchers point out that plant-derived haemoglobin is easily purified and sterilised, and there may be other plant species that can produce higher yields. Until others can be found, however, the tobacco plant has proved that it is not all bad.
