Implants like pacemakers and insulin pumps often fail because of immune attacks − stopping them could make...
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Biomedical implants – such as pacemakers, breast implants and orthopedic hardware like screws and plates to replace broken bones – have improved patient outcomes across a wide range of diseases. However, many implants fail because the body rejects them, and they need to be removed because they no lo...
nger function and can cause pain or discomfort. An immune reaction called the foreign body response – where the body encapsulates the implant in sometimes painful scar tissue – is a key driver of implant rejection. Developing treatments that target the mechanisms driving foreign body responses could improve the design and safety of biomedical implants. I am a biomedical engineer who studies why the body forms scar tissue around medical devices. Along with my colleagues Dharshan Sivaraj, Jagan Padmanabhan and Geoffrey Gurtner, we wanted to learn more about what causes foreign body responses. In our research, recently published in the journal Nature Biomedical Engineering, we identified a gene that appears to drive this reaction because of the increased stress implants put on the tissues surrounding them. Many implants need to be replaced because the immune system damages them over time. Mechanics of implant rejection Researchers hypothesize that foreign body responses are triggered by the chemical and material composition of the implant. Just as a person can tell the difference between touching something soft like a pillow versus something hard like a table, cells can tell when there are changes to the softness or stiffness of the tissues surrounding them as a result of an implant. The increased mechanical stress on those cells sends a signal to the immune system that there is a foreign body present. Immune cells activated by mechanical pressure respond by building a capsule made of scar tissue around the implant in an attempt to shield it off. The more severe the immune reaction, the thicker the capsule. This protects the body from getting an infection from injuries like a…