Few people associate tobacco with good health. But now a team of researchers at Pacific Northwest Laboratories (PNL), led by biochemical engineer Brian S. Hooker, are genetically modifying tobacco plants to produce a substance that could help save lives. It’s called factor VIII and it helps hemophiliacs’ blood to clot. Hooker is working with tobacco because it is a well-understood and easily manipulated plant.
Hemophilia is an hereditary life-threatening disease which affects blood’s ability to clot. The disease affects about 20,000 people in the United States. It’s caused by a missing or malfunctioning gene responsible for manufacturing blood factor VIII, a vital factor in the clotting mechanism. Without factor VIII, hemophiliacs can literally bleed to death from a bruise.
An historically famous hemophiliac was Tsarevitch Alexis, the only son of Tsar Nicholas II of Russia. He inherited the disease from his great-grandmother Queen Victoria of England.
|image: New York Blood Banks|
Before factor VIII was isolated, hemophiliacs led short, painful lives. With regular injections of this vital component, hemophiliacs can lead near-normal lives. Currently, the factor is either isolated from donated blood plasma, or produced in other animals such as hamsters using recombinant DNA technologies.
According to Brian Hooker of PNL, producing the factor using these methods costs up to $1 million per gram. But hope is high for another solution.
Safer and Cheaper
Hooker’s team, is producing factor VIII from tobacco leaves because it’s about 20 times cheaper and safer: unlike human blood, plants don’t harbor human viruses.
"Currently, 20 percent of all hemophiliacs in the United States are HIV positive because they receive blood products or clotting factors that have been tainted with the AIDS virus," Hooker says. Some organizations, such as the New York Blood Center, state that as many as 80 percent of hemophiliacs have contracted hepatitis B.
But don’t blood services screen out HIV-tainted blood? Hooker points out that "it’s approximately 22 days after somebody is infected with HIV before you can test, and test positive for HIV infection. So there is a window of time... where the virus will not ramify itself. There is always a risk of viral transmission."
With the advent of plant-produced factor VIII, the possibility of these viruses is eliminated. "I cannot get [a] tobacco virus from a tobacco plant and... if I have a cold or a flu or hepatitis B, and I breathe on that tobacco plant, that plant is not going to contract disease from me," Hooker says. Using transgenic plants there is no possibility of viral transmission because plants do not harbor human viruses.
The price of manufacturing the essential factor is much reduced when using the technique – about $5,000 per gram, Hooker says. Hooker also notes that a single greenhouse could supply "the entire world’s demand" for factor VIII.
Hooker also envisions producing a sutureless sealant from tobacco plants. "Say you had a surgery and it was time to close the surgical incision. This solution would be sprayed on just from a simple aerosol spray can then the wound sites would be healed up, actually adhere to [itself] and the clotting process would initiate."
Hooker starts with determining the genetic makeup of factor VIII. He then separates out the gene which is responsible for factor VIII and inserts it directly into the chromosomes of a tobacco leaf. The tobacco plant is fooled into believing the human gene is part of its normal chromosomal makeup.
After three days, the team takes pieces of the leaf, now expressing the blood factor gene, and cultures new plants, just as a house plant is rooted to grow a new one. After the plants mature, Hooker removes the leaves, squeezes out the extract, stabilizes the factor VIII, and purifies it. He says tobacco-based factor VIII could be ready to market in five to seven years.
He even envisions producing whole blood from tobacco plants one day -- but no time soon. "I see 99.9% of everything that is in whole blood within 50 years there will be some type of surrogate made through biotechnology."
Elsewhere on the Web
National Hemophilia Foundation
Hemophilia Information from NIH
World Federation of Hemophilia
Genetics Institutes "Hemophilia Village" site