X-ray scan of a hip joint replacement orthopedic implant. (Getty Images)
X-ray scan of a hip joint replacement orthopedic implant. (Getty Images)

New NIH funding will support research into how the body responds to medical implants

A Virginia Commonwealth University engineering professor has received a $1.76 million grant to further his research on tissue healing and investigate how immune system cells control the body’s response to biomaterials such as a dental implant or hip replacement.

René Olivares-Navarrete, D.D.S., Ph.D., an assistant professor in the Department of Biomedical Engineering in the College of Engineering, will receive the grant from the National Institute of Dental and Craniofacial Research at the National Institutes of Health.

The body’s immune system is critical to the success of an implant, but how the inflammatory response is controlled is not known. Olivares-Navarrete’s research focuses on understanding the immune system’s role in biomaterial integration, tissue healing and regeneration. The long-term goal is to understand what factors promote faster recovery in patients with medical implants.

“We are interested in what happens immediately after surgery because that will dictate what happens later,” Olivares-Navarrete said.

Among the first cells to interact with an implant are immune system cells called macrophages, a type of white blood cell that stimulates other immune cells. Olivares-Navarrete’s previous experiments have identified the significant role of macrophages, which can promote healing by leading an anti-inflammatory response and recruiting additional stem cells to the site.

Olivares-Navarrete is investigating the process by which these cells and a type of protein they produce may orchestrate cells to respond to different kinds of surfaces on the implants, become pro-inflammatory or anti-inflammatory and recruit stem and immune cells. A greater understanding of how these proteins work also could lead to discoveries in other areas such as chronic inflammatory diseases and cancer.

Being able to control the duration of the inflammatory response is key to the healing process, he said. A lack of inflammation results in no healing. On the other hand, he said, “a chronic inflammatory response [also] translates to no healing.” The “sweet spot” may be acute, but brief, inflammation.

Olivares-Navarrete’s lab previously demonstrated that macrophages respond to the material surface properties of metallic implants. For instance, when the surface of an implant is rough and hydrophilic, or attracts water, the macrophages recruit more stem cells than when the surface is either smooth or rough and hydrophobic, or water-repellent.

“The overall idea is to understand which parameters the materials should have on their surface to improve and enhance the healing response,” Olivares-Navarrete said. “You can control the healing behavior with modifications in the surface materials.”

Barbara D. Boyan, Ph.D., the Alice T. and William H. Goodwin Jr. Dean of the College of Engineering, said, “Dr. Olivares-Navarrete and his team are one of the leading groups providing information about how the immune system is affected by biomaterials and why rough-hydrophilic surfaces cause a pro-healing inflammatory response.”

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