Scientists Create Self-Deploying, 4D Printed Vascular Stent

Cardiovascular diseases are a major global health concern. Various complications that affect normal blood flow in arteries and veins, such as stroke, blood clot formation in veins, blood vessel rupture, and coronary artery disease, often require vascular treatments.

Existing vascular stent devices, however, often require complex, invasive deployment procedures. These procedures necessitate the search for novel materials and manufacturing technologies that could help vascular stents work more naturally with the body. Moreover, developing patient-specific, adaptively deployable vascular stents is key to further advancing minimally invasive cardiovascular therapies and making vascular treatments safe and less burdensome for both patients and healthcare providers.

Driven by the need for better vascular treatments, researchers from Japan and China—led by Professor Dr. Shinjiro Umezu from the Graduate School of Advanced Science and Engineering, Waseda University, (Japan)—has developed a new 4D-printed vascular stent that naturally expands at body temperature, thereby eliminating the need for external heating and potentially enabling safer and less invasive treatments.

The team comprised Yannan Li, Yifan Pan, Chaolun Xu, Jianxian He, Jingao Xu, Dr. Kewei Song, and Dr. Ze Zhang from Waseda University; Prof. Chikahiro Imashiro and Dr. Kayo Hirose from The University of Tokyo, Japan; Dr. Chen Gao from Southeast University, China; Dr. Junbo Jiang from South China University of Technology; and Prof. Runhuai Yang from Anhui Medical University, China. Their findings were published online earlier this year in Advanced Functional Materials (“Adaptive 4D-Printed Vascular Stents with Low-Temperature-Activated and Intelligent Deployment”).

In their study, the researchers leveraged a polycaprolactone-based shape-memory polymer composite to fabricate micro-architected coronary artery stents through projection micro-stereolithography 4D printing technology. This technology utilizes ultraviolet light to create micro-sized objects with high-resolution features. Scientists used this technology to create such micro-coronary artery stents. Notably, they precisely modulated the thermal transition temperature to approximately 37 °C by using diethyl phthalate as a plasticizer, facilitating quick and automatic shape recovery with no external heating.

Finite element simulations and a viscoelastic stress relaxation model confirmed the developed stents remarkably balance mechanical flexibility and radial strength, and demonstrate long-term biomechanical compliance. While in-vitro studies using human umbilical cells exhibited excellent cytocompatibility, in vivo implantation experiments in mice indicated the potential for clinical application.

“Our work provides a robust platform for next-generation adaptive vascular stents with programmable mechanics, intelligent deployment, smoother integration with the human body, and reduced need for complex procedures, offering significant potential for personalized treatment in anatomically complex vascular structures,” Dr. Umezu noted.

The researchers’ work may help address challenges in vascular treatments and could be used in other implantable medical devices. The coronary artery stents developed in this study highlight high operational feasibility and engineering controllability. These advantages also demonstrate highly tunable and personalized fabrication of stents for diverse patient groups.  The study findings showcase a generalized approach for developing vascular implants, with significant potential for clinical translation.

“Consequently, our research could contribute to future vascular stent technologies used in minimally invasive procedures, potentially simplifying deployment and reducing the need for additional equipment. The same approach may be applicable to other implantable medical devices that are designed to respond to the body’s natural environment,” Dr. Umezu said.

Dr. Umezu is a professor at Waseda University, Japan. He is affiliated with both the Graduate School of Advanced Science and Engineering, Department of Integrative Bioscience and Biomedical Engineering, as well as the Graduate School of Creative Science and Engineering, Department of Modern Mechanical Engineering. His research interests include mechanical engineering, mechanics and mechatronics, robotics and intelligent systems, green fabrication, biofabrication, and 3D printing. He has published about 300 research papers on these topics and received more than 2,000 citations. He is a member of Japanese Society of Mechanical Engineers and Society of Precision Engineering.

Study authors: Yannan Lia,^a Yifan Pan,^b Chikahiro Imashiro,^c Chaolun Xu,^b Jianxian He,^b Jingao Xu,^b Kewei Song,^b Ze Zhang,^b Chen Gao,^e Junbo Jiang,^f Runhuai Yang,^g Kayo Hirose,^d and Shinjiro Umezu.^a,b

Affiliations
^a Graduate School of Advanced Science and Engineering, Department of Integrative Bioscience and Biomedical Engineering, Waseda University, Japan
^b Graduate School of Creative Science and Engineering, Department of Modern Mechanical Engineering, Waseda University, Japan
^c Graduate School of Engineering, The University of Tokyo, Japan
^d Anesthesiology and Pain Relief Center, The University of Tokyo Hospital, Japan
^e School of Biological Science and Medical Engineering, Southeast University, China
^f Department of Rehabilitation Medicine, Guangzhou First People’s Hospital, School of Medicine, South China University of Technology, China
^g The Chaohu Hospital of Anhui Medical University, China