(Nanowerk Spotlight) Millions of medical procedures every year rely on stents—small mesh-like tubes—to keep body channels open when diseases threaten to close them off. These stents help restore blood flow, keep airways open, and maintain the function of passages in the digestive and urinary systems. Yet, existing stent technologies, particularly metallic ones, often lead to unwanted side effects such as inflammation, rejection, and scarring.
Overcoming these issues has proven difficult because traditional stent coatings, often made from synthetic plastics or silicone, do not integrate well with the body’s tissues. These synthetic materials lack the capacity to promote natural cell growth and struggle to deliver medications directly to affected areas effectively.
Despite recent progress using advanced manufacturing techniques, such as electrospinning and 3D printing, significant challenges remain. Electrospun coatings often detach under repeated mechanical stress. Meanwhile, 3D-printed stents, though precise, typically fail to match the strength and flexibility required by metallic stents in dynamic body environments. The absence of a fully integrated and biologically friendly coating has severely limited stent effectiveness in clinical practice.
A recent research study (Advanced Functional Materials, “Stable and Integrated Nanocellulose-Covered Stents via In Situ Microbial Synthesis”) led by Nannan Yang and colleagues at Shanghai Jiaotong University proposes an innovative solution: harnessing bacteria to build integrated stent coverings from bacterial nanocellulose (BNC). Bacterial nanocellulose is a natural, flexible material produced by bacteria known as Komagataeibacter xylinus. These bacteria produce fine cellulose fibers under conditions rich in oxygen, creating a strong, porous mesh that closely mimics human tissue.
To develop this new approach, the researchers began by coating metallic stents with calcium peroxide nanoparticles encapsulated within a gelatin-based gel. Upon exposure to moisture in a specialized bioreactor, these calcium peroxide particles released a controlled stream of oxygen. This oxygen attracted the cellulose-producing bacteria, guiding them directly onto the metal stent’s surface. Over several days, the bacteria gradually produced a dense, fiber-based network that integrated naturally and securely around the metallic stent structure.
Schematic diagram. CaO2 nanoparticles were coated on the metal rod of the metal stent through the photocuring process of GelatinMethacryloyl (GelMA) hydrogel. Furthermore, during the cultivation process, CaO2 nanoparticles undergo hydrolysis to release oxygen, enabling the colonization of aerobic bacteria (Komagataeibacter xylinus) around the metal rod and the production of BNC. Ultimately, an integrated BNC-coated stent was constructed. Furthermore, the BNC-covered stents could be utilized for the loading of drugs such as paclitaxel (PTX). (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge)
What makes this method particularly valuable is its seamless integration. Unlike previous methods, where coatings simply adhere loosely to the stent, the bacteria-generated cellulose grows directly into the metal frame. This ensures extraordinary durability and mechanical stability. Rigorous mechanical testing showed that the BNC-covered stents remained intact after 10,000 repeated cycles of compression, far exceeding the stresses that stents typically encounter in clinical use.
Further testing revealed remarkable biocompatibility. When implanted into rabbits’ airways, the BNC-covered stents maintained perfect airway openness and showed no inflammation or tissue damage after two weeks. This is a significant improvement over traditional metal stents, which often trigger immune responses or scarring that can lead to complications or stent failure.
One of the most promising capabilities of this BNC-coated stent is its ability to precisely deliver drugs. In laboratory and animal studies, the researchers embedded paclitaxel, a chemotherapy drug, directly into the cellulose fibers. Their tests showed that paclitaxel was released slowly and consistently, effectively eliminating cancer cells while leaving surrounding healthy tissue largely unharmed. This targeted drug delivery is critical, particularly for treating tumors or localized inflammation in hollow organs such as airways, blood vessels, or the digestive tract.
In a demonstration using 3D-printed models from actual clinical data, the team also confirmed that their BNC-coated stent could be tailored precisely to match specific anatomical structures. They successfully created asymmetrically coated stents, delivering drugs only to targeted tumor sites, further enhancing their therapeutic precision. This adaptability opens the door to personalized medical treatments, allowing clinicians to craft stents specifically for individual patient anatomy and clinical needs.
Yet, the researchers acknowledge that several hurdles remain before widespread clinical use. While promising, bacterial cellulose production must be carefully controlled and standardized for clinical safety. Regulatory approval will require comprehensive evaluation of manufacturing consistency, safety protocols, and longer-term biocompatibility in larger patient populations. Cost and scalability also remain practical challenges that must be addressed to ensure broad accessibility in medical practice.
Despite these considerations, the potential of integrated bacterial nanocellulose-covered stents is significant. Beyond airway and cancer treatments, these stents could revolutionize procedures involving blood vessels, gastrointestinal obstructions, and urinary tract issues. With further refinement, this approach could represent a meaningful shift toward safer, more effective, and individually tailored medical interventions.
This study demonstrates how an integration of biology and engineering can result in highly effective medical technologies. By leveraging nature’s ability to construct precise and compatible structures, these scientists have developed a stent platform that offers new hope for improved outcomes across a wide range of medical applications.
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