Coatings & surface treatment
Advancements in medical adhesives are paving the way for more reliable and long-lasting implants by reducing scar tissue formation.
“This work really has identified a very general strategy, not only for one animal model, one organ or one application,” said MIT postdoc Jingjing Wu and lead author of the Nature paper in an accompanying press release. “Across all of these animal models, we have consistent, reproducible results without any observable fibrotic capsule.”
In another experiment, the researchers coated implants with the same hydrogel treated with a solution that neutralised its adhesive properties while preserving its overall chemical composition. Once implanted in the body and secured with sutures, these modified implants did trigger fibrotic scarring. According to the researchers, this finding suggests that the adhesive’s mechanical interaction with the tissue plays a critical role in preventing the immune system from initiating an inflammatory response. The team also tested a hydrogel adhesive that included chitosan, a naturally occurring sugar, which similarly eliminated fibrosis in animal studies. Two commercially available tissue adhesives were tested as well, but they failed to mount an antifibrotic effect, eventually detaching from the tissue and allowing the immune system to attack.
A universal approach Traditional approaches to mitigating fibrous capsule formation often rely on surface modifications or drug- eluting coatings, says Zhao. But this dependence on specific substances can be a limitation, given that we need solutions for a wide variety of medical devices that are made from diverse materials.
On the other hand, hydrogel adhesive can be used with any material and is drug free, meaning it can be
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applied to implants of any material – be it metal, plastic or silicone. This universality represents a significant leap forward, as it simplifies the process of creating and applying implant coatings. For instance, there’s no need for complex formulations or tailored approaches – you just use the adhesive. “I was so surprised to see the broad applicability of the adhesive non-fibrotic interface on diverse organs [and] in various animal models,” says Zhao. One potential application is as a coating for epicardial pacemakers, devices attached directly to the heart to regulate its rhythm. The wires connecting these to the heart often become encased in fibrotic tissue, which can impair their function. However, the MIT team demonstrated that when adhesive-coated wires were implanted in rats, they remained fully operational for at least three months without evidence of scar tissue formation. The adhesive has only been tested in animal models, so clinical research is needed before it can be deemed safe for humans. But Zhao’s team are working on it: they’re currently studying more detailed interactions between the hydrogel adhesive and the immune system, while exploring additional applications. To accelerate commercialisation, the MIT researchers founded SanaHeal, a startup pursuing clinical trials and FDA approval for products based on this bioadhesive technology. It’s the dream of many research groups and companies to create an implant that, over the long term, the body doesn’t ‘see’ yet that still does what it’s supposed to, whether that’s to diagnose or deliver therapy, says Zhao. “Now we have such an ‘invisibility cloak’... There’s no need for a drug, no need for a special polymer.” ●
Medical Device Developments /
www.medicaldevice-developments.com
Denis---S/
Shutterstock.com
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