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Viruses that mimic supportive nerve tissue may someday help regenerate injured spinal cords. While other tissue-engineering materials must be synthesized and shaped in the lab, genetically engineered viruses have the advantage of being self-replicating and self-assembling. They can be designed to express cell-friendly proteins on their surfaces and, with a little coaxing, be made into complex tissuelike structures. Preliminary studies show that scaffolds made using a type of virus called a bacteriophage (or phage) that infects bacteria but cannot invade animal cells can support the growth and organization of nerve cells.
Researchers working on tissue engineering hope to eventually be able to use a patient’s own cells to grow replacement tissue for damaged hearts, livers, and nerves. But mimicking the structure and function of the body’s tissue has proved difficult. Matrices of supportive, fibrous proteins sustain the cells of the heart, lungs, and other tissues in the body. These scaffolds provide both structural support and chemical signals that enable an organ or nerve tissue to function properly.
Some biological engineers are using scaffolds made of polymers to try to mimic the supportive matrix of real tissue. Seung-Wuk Lee, a bioengineer at the University of California, Berkeley, has turned to viruses instead. “Viruses are smart materials,” he says. “Once you construct the genome, you can make billions of phages, and they’re self-replicating materials.” The phage that Lee is working with, called M13, is long and thin like the protein fibers that make up the cellular matrices inside the body.