The immune system’s foreign body response is important for keeping us healthy – but it’s not so useful when that foreign body is a medical implant. Researchers at MIT have now developed a device that prevents scar tissue forming around implants by gently inflating and deflating every 12 hours.
When the immune system detects an object that doesn’t belong in the body, it mounts a response to prevent infection or other complications. Part of that response involves forming a thick layer of scar tissue around the object, to wall it off from blood vessels and tissues.
But that causes problems when said object is a vital medical implant. That scar tissue can block its function, whether that’s drug release or stimulating nerves or neurons, reducing the device's usefulness over time. In previous work, scientists have experimented with changing the size of implants, designing lubricated or drug-doped coatings, making implants out of soft hydrogels, or cloaking implants with a collagen gel containing blood vessels.
For the new study, the MIT team developed a novel technique to combat scar tissue formation – every 12 hours, the device is repeatedly inflated and deflated over five minutes. That has the effect of reducing the local concentration of neutrophils, the immune cells that kickstart the scar tissue formation process.
The device contains two chambers – one that holds the drug payload, while the other acts as the inflatable “actuation reservoir.” The drug will slowly seep out into the body over time, or can be released in a larger burst by the actuator.
The team says that although the actuated implant can’t completely prevent scar tissue formation, it was effective at slowing the process down. But more importantly, it changed the type of scar tissue that did form to a structure with highly aligned collagen fibers, which didn’t impede the release of drug molecules as much as regular scar tissue.
The team tested the device in mice, delivering insulin and measuring the blood glucose levels of the animals. Sure enough, the actuated version continued to release insulin effectively throughout the eight-week test period. That’s a much better performance than a standard non-actuating device, which began to lose effectiveness after just two weeks and was delivering almost no insulin at all by the eight-week mark.
Next, the researchers plan to scale up the device to human size, to help patients control diabetes or deliver other long-term drug regimens like chemotherapy.
The research was published in the journal Nature Communications.
Source: MIT
