Adhesive Hydrogel Prevents Scar Tissue Formation in Medical Implants

MIT’s new adhesive hydrogel coatings have significant potential to enhance implanted medical devices’ long-term performance and reliability.

Implanted medical devices often lose functionality over time due to foreign body reactions and fibrous capsule formation. To address this issue, researchers have explored various solutions, and one promising approach involves using adhesive hydrogel coatings. These coatings significantly reduce fibrosis and extend the lifespan of medical devices by minimizing inflammatory cell infiltration.

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In a series of rigorous experiments, MIT researchers thoroughly tested the adhesive implant in various animal models, ranging from rats and mice to humanized mice and pigs. The results of these tests demonstrate two key findings. Firstly, the adhesive securely bonds devices to the surrounding tissue. Secondly, it effectively shields them from immune attacks, thus eliminating the development of fibrosis.

Adhesive Hydrogel Interfaces

MIT Researchers explored the effects of the adhesive hydrogel interfaces with varying compositions and properties. Initially, they constructed a structure comprising interpenetrating networks. This structure amalgamated covalently crosslinked poly (acrylic acid) N-hydroxysuccinimide ester with physically crosslinked poly (vinyl alcohol). Subsequently, they replace the poly (vinyl alcohol) – based adhesive interface with chitosan. The findings yielded surprising results. Despite its distinctive composition and Young’s modulus, the chitosan-based adhesive interface demonstrated adhesion performance comparable to its poly (vinyl alcohol) counterpart.

Engineers also tested two commercially available tissue adhesives, but these did not exhibit the anti-fibrotic effect. The commercially available adhesives eventually detached from the tissue, allowing the immune system to attack.

Testing the Impact of Adhesive vs. Non-Adhesive Implants

Scientists conducted experiments with adhesive and non-adhesive implants across various organs in animal models over 84 days. Over time, the non-adhesive implants developed fibrosis, while the adhesive implants did not.

To analyze the foreign body reaction and fibrous capsule formation, researchers conducted histological analyses. These analyses confirmed the absence of fibrous capsules in organs with adhesive implants over 12 weeks. Additionally, they performed in vitro protein adsorption studies, multiplex Luminex assays, quantitative PCR, immunofluorescence analysis, and RNA sequencing to further investigate the effects.

Furthermore, they demonstrated sustained bidirectional electrical communication facilitated by implantable electrodes with an adhesive interface over 12 weeks in vivo. These compelling findings propose a promising strategy for developing long-term anti-fibrotic implant–tissue interfaces. The results showed that the conformal interfacial integration between the adhesive implant and the tissue surface reduces the infiltration of inflammatory cells. These cells include neutrophils, monocytes, and macrophages. This reduction in infiltration diminishes collagen deposition and long-term fibrous capsule formation.

Anti-fibrotic potential

Adhesive anti-fibrotic interfaces hold the potential to revolutionize medical implant technology. They offer new hope for enhancing the longevity and reliability of implanted medical devices across diverse organs. Therefore, after multiple years of research, the Senior authors of the MIT study launched a company called SanaHeal. This company dedicates itself to further developing tissue adhesives for medical applications. Their current focus extends beyond chemistry and biochemistry to investigate how mechanical cues affect the immune system.

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