Hernia meshes: new answers to an old problem
According to the National Center for Health statistics, nearly 5 million Americans suffer from the most common types of hernias, which occur in the abdomen. Hernias are bulges caused by organs protruding though weak spots in the muscles that are intended to hold them in place and are sometimes quite dangerous.
Hernias are commonly repaired with the insertion of a mesh patch, which can be administered during laparoscopic surgery. However, these meshes, primarily made of polyester, polypropylene or Teflon, can experience approximately a 10 percent failure rate.
“In 2005, Bruce Ramshaw (former chief of surgery at the University of Missouri Medical Center), called to see if I could help with a mesh material study,” said Sheila Grant, MU associate professor of biological engineering. “Hernia meshes were shrinking; their properties were changing and patients were experiencing pain and infection,” she added, explaining that Ramshaw is a leader in laparoscopic surgery for hernia repair.
The pair joined forces with Sharon Bachman, MD, an assistant professor with the MU School of Medicine, to collect and characterize failed hernia meshes removed from patients. Besides determining changes in the engineering properties of the hernia mesh, the team also collects patient demographics. All this information is fed into a database that allows correlations to be performed. The group titled their organized program to study potential ways to address the problem Biomaterials Innovation Characterization and Analysis of Missouri, or BICAM.
“Medical device companies realize the importance of analyzing the meshes,” Grant said. “We received funds and/or equipment from Covidien – which actually gave $750,000 – MTF, Smith & Nephew and Atrium.”
BICAM has collected over 300 explants through an approved institutional review board (IRB).
Grant explains that by looking at the explants and the associated patient data, she and her research assistants are able to document factors that, in some cases, may have led to failure.
“Nicotine use causes enhanced inflammatory response, which can cause degradation,” she said. “Diabetes and a high body mass index are also factors that contribute to problems.”
Grant’s graduate and undergraduate bioengineering student assistants are perfecting cleaning techniques for the explanted meshes, a necessary first step before examining them to characterize their degradation.
“One of my biggest rewards is getting to work with undergrads,” said Grant. “Besides helping me to decipher what went wrong, this research helps students with their career goals.”
A student in Grant’s biomaterials class worked a co-op with Covidien and another landed a job with the company. MTF and Smith & Nephew also have hired her research assistants. She estimates that she has worked with 25 undergraduate students in her lab.
Graduate student Matt Cozad is looking at swine tissue as a potential “biologic” mesh material. Grant explains that these types of mesh would greatly reduce the risk of infection and promote tissue integration. “But biologics are much more expensive,” she said. “A 10 by 10 centimeter piece can cost $10,000. Synthetics are much less expensive.”
“You want to see tissue and cellular integration of hernia meshes, which will reduce the foreign body reaction, but a lot of those on the market aren’t doing that,” said Grant. “We’ve developed a new mesh that will enhance tissue integration and have applied for a patent.”
Grant said that because a strong patient advocacy group approached the Food and Drug Administration (FDA) with their problems, they are very interested in new ideas.
“Companies are starting to listen to us,” Grant said. “Our program is getting big enough that people are starting to recognize us.”