Bioengineered fibrogen 'glue' a revolutionary 'bandage' for extreme bleeding cases

Imagine a type of glue that will reconstruct bone, stop extreme bleeding, or deliver chemotherapy drugs directly to cancer cells. This revolutionary material exists and it comes from the milk of a transgenic pig

William Velander, a Virginia Tech biochemical engineer, has collaborated with the American Red Cross (ARC) for 11 years to develop therapeutic proteins for these uses. The ARC is now forming new business relationships with biotechnology companies to bring this next generation of health care products and services to market.

Already, the non-profit ARC has announced an historic alliance with Pharming, a biopharmaceutical company based in the Netherlands. Working with Pharming, ARC will develop and market Factor VIII, or fibrinogen, and Factor IX, both produced in the milk of transgenic animals using technology pioneered by William Drohan at ARC’s Jerome Holland Laboratory, in conjunction with Velander’s work at Virginia Tech’s Pharmaceutical Engineering Institute.

Both Factor VIII and Factor IX serve as coagulants for the treatment of hemophilia. Fibrinogen is a protein in the blood plasma that is converted to fibrin and can form a fibrous network in the coagulation of blood. All of these proteins are present in human blood but in such small amounts that cost prohibits their use as pharmaceuticals. For example, fibrinogen from human blood, used to treat a hemophiliac, typically costs the patient tens of thousands of dollars per year.

The Virginia Tech-ARC collaboration began at a 1986 National Science Foundation workshop, "Look to the Future." The workshop’s sponsors were interested in the administration of blood-based therapies; at that time, the contamination of the blood supply with the HIV virus was having disastrous consequences. Some 50 percent of all hemophiliacs born before 1987 had HIV infection. A drastic change was necessary.

Enter Velander and Drohan, who decided to synthesize very complex proteins in a genetic engineering process that would provide a sterile environment. Velander says the results have made possible an "increase in the quality of the health care system while decreasing the cost."

The blood clotting proteins they wanted to manufacture included Protein C, Factor VIII, and Factor IX, and Factor VIII, or ‘fibrinogen’.

Fibrogen, "probably the most complex protein ever to be synthesized in any genetically engineered cell," is used for "traumatic wound healing, particularly for stopping the bleeding, and -- in the most novel and exciting applications -- the delivery of drugs and chemotherapies for treating cancer, as well as bone and vascular reconstruction," Velander says.

On a military battlefield, most casualties result from loss of blood. Fibrinogen, immobilized on a gauze and placed on a catastrophic wound, reacts with thrombin, an enzyme, to make a fibrin clot.

Administering tetracycline is an example of fibrinogen’s effectiveness as a drug delivery mechanism. If this antibiotic is delivered in a fibrin glue, it can retain an effective concentration for 42 days – that’s a 100-times higher concentration than if it is taken orally. "Many infections show a resistant behavior when they are not really resistant. They just need a higher dosage of an antibiotic," Velander explains.

Similarly, an application of fiber sealant placed exactly where cancer cells are located has shown in preliminary trials to have eliminated the normally highly invasive disease.

The third important application of fibrinogen is for bone reconstruction, which Velander labels "the most exciting application of drug delivery using fibrin glue." In one experiment, bone was excised from the skull of a mouse and replaced by a molded implant containing demineralized bone powder, bone growth factor, and fibrin. "It brought about a perfect regeneration of the bone in the skull of the animal," Velander reports.

In a human, the very complex proteins that Velander is using are normally made in the liver. He and Drohan wanted to produce them in mammary tissue so that they could be secreted. The advantage of producing proteins in milk is more proteins remain alive. In the liver, many die because they have no way to exit the body.

The researchers elected to use a pig as their transgenic bioreactor because this mammal is easy to clone, very trainable as a "milking machine," and produces about 300 liters of milk per year. Another consideration is that swine are resistant to mad cow disease.

Since she feeds her young every hour, a sow makes Protein C at about two tenths of a gram per liter per hour, which is about a 60-times higher concentration than is in human blood, and 500 times higher than scientists have produced with any cell culture system.

Velander explains the process for producing milk that specifically contains the human Protein C, or any other therapeutic protein: A gene is removed from a mouse milk protein normally found in the whey of its milk. The gene is cloned, and a copy of the human Protein C gene is inserted. The gene is then placed into the pig. As Velander explains, "I have a mouse milk gene that has a human gene that is now inside a pig...." The mouse gene instructs the pig’s DNA where to produce the attached human protein. Genie, Velander’s first transgenic pig to produce Protein C, made about one gram per liter of milk, 200 times the concentration of this protein in normal human blood plasma.

"In the future, we are going to have a portfolio of therapeutics that are made in the milk of different animals," the biochemical engineer believes. Scientists will be relying on different species because "there are species-specific effects" where cows may be the better choice than pigs for one protein, and sheep might be a better choice for yet another, Velander adds.

Contact for more information, William Velander, 540-231-7869