Toward an artificial trachea
Tissue engineering is making great strides in many fields of medicine—and according to otolaryngology–head and neck surgery fellow Alexander Hillel, this one is no exception.
“There are few specialties,” he says, “where tissue engineering could be so versatile and make such a difference for our patients.”
For example, Hillel and his colleagues recently published research on combining synthetic and biologic materials into a material that could eventually act as a handy filler for restoring soft tissue. Current fillers include materials like combinations of collagen and hyaluronic acid. Though these work well for filling small defects, such as those in common cosmetic procedures, their lifetime before the body dissolves these materials is too short to use for more extensive facial plastic surgery, such as repairing the much larger defects introduced by surgeries to remove tumors.
The new material is a mix of a chemical called hyaluronic acid and a polymer called polyethylene glycol (PEG), a synthetic material so biologically friendly that it’s already being used in other biomedical applications, such as drug delivery. This combined material gets firmer following light exposure, Hillel explains, so that physicians who use this filler could have the chance to mold it before it takes its final shape. He adds that altering the proportion of PEG changes the firmness of the material, giving it versatility for a variety of uses, from filling nasolabial folds—the “parentheses marks” that frame your smile over time—to larger defects in the skull.
Hillel’s other recent successes have involved creating a variety of three-dimensional structures combining cells and scaffolding materials. For example, he and his colleagues recently published work showing the potential of growing engineered fat tissue and cartilage using cells and a PEG-based scaffold. These synthetic tissues could eventually replace those that patients lose from injury, disease, or aging.
Because his clinical interests focus more on the voice and airway, Hillel plans to combine what he’s learning through these experiments to construct an engineered trachea, work that could provide new options for patients with airway narrowing from a variety of causes, such as frequent placement of breathing tubes and a disease called Wegener’s granulomatosis. Starting with tracheas from cadavers, with all living cells removed, he’s currently working on finding the right stem cell types to place on these natural scaffolds to create something long sought in medicine—a substitute for damaged tracheas that enables full and effective breathing.
“We have some obstacles to overcome before we can translate this therapy,” Hillel says. However, he adds that he has no doubt it will eventually help a select group of patients with no alternative. “This field is progressing so quickly. For tissue engineering, the future is now.”
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