Insight
September 2015 
When a patient has a tumor removed, surgeons may fill the cavity using silicone implants, soft tissue from another part of the patient’s body—or use no filler at all. Each option has drawbacks, such as scar formation, the need for replacement, additional surgical procedures or concerns about appearance.
But now, Johns Hopkins plastic surgeons and biomedical engineers have invented a composite material that supports a surgical cavity while encouraging new tissue growth within it. The composite has performed well in small-animal tests.
Two years ago, plastic and reconstructive surgeon Justin Sacks and surgical resident Sashank Reddy approached materials engineer Hai-Quan Mao in the Translational Tissue Engineering Center with a new idea. They wanted to reconstruct new soft tissue for patients after breast cancer removal using a soft material that surgeons could custom fit to fill a cavity.
Mao suggested trying hydrogels because they are jellylike and have elastic properties that mimic the feel of soft tissue. Some hydrogels are already in use to fill small-volume defects for cosmetic reconstruction. However, it can be difficult to achieve both material strength that matches soft tissues and sufficient pore structure that encourages new tissue growth.
In the end, the team developed a new material that combined hydrogel and nanofibers made with the same polymer materials used in degradable sutures. “We bonded the nanofibers with the hydrogel and made a stronger composite that can hold its shape until new tissue grows in the pores of the composite,” says Mao.
As new cells and blood vessels grow in the framework, the composite slowly degrades.
Mao and the team have submitted a patent on the composite and recently received a Johns Hopkins-Coulter Translational Partnership grant for large-animal studies to prepare for the clinical translation to treat patients within the next few years.
