3D Printing Bioresorbable Stents
Stents were introduced to medicine in the mid-1980s for use in percutaneous coronary interventions and nephrological procedures. Since then, they have undergone significant evolutions but still present several problems such as restenosis in cardiac applications, related to the fact that they do not degrade, remaining in the patient's body forever [1]. As a solution to this problem, bioresorbable stents are being developed to replace conventional stents. They are composed of bioresorbable materials that can be absorbed by the human body. Thus, they would provide the necessary initial mechanical support and then degrade, avoiding long-term complications [2].
Currently, the scientific community has been directing efforts towards the development of non-permanent polymer-based bioresorbable stents. These stents would disintegrate over several months, thus minimizing the risk of restenosis without the need for surgical removal. In addition to providing significant benefits for pediatric cases, when a stent may not grow appropriately inside the patient. Polycaprolactone (PCL) has become an ideal candidate for this type of application due to its good ductility, processing properties, biodegradability, and biocompatibility [2].
Figure 1: 3D bioprinting strategy to print PCL stents [2].
To manufacture these polymer-based bioresorbable stents, 3D printing techniques have been extensively applied, as it delivers personalization, allowing patient specificity, which could improve the patency of the vessel. Several studies suggest that the 3D printing process is highly suitable for manufacturing composite stents, even though it is still in its initial stage, requiring more research to be developed in terms of quality and biocompatibility assessment for bioresorbable stents [2,3].
Guerra et al. (2018) developed PCL / PLA composite stents using a new tubular 3D printer based on Fused Deposition Modeling (FDM). According to the results of this study, the 3D printing process was approximately 85–95% accurate. PCL / PLA composite stents demonstrated great potential in tests of degradation, dynamic mechanics, and expansion for the proposed application. The outcomes of this work indicate that composite PCL / PLA stents are a promising solution to meet the stringent requirements for bioresorbable stents [4].
In addition to 3D stents targeted at cardiac applications, Paunovic et al. (2021) reported the fabrication of customized and bioresorbable airway stents using digital light 3D printing. The stents exhibited adjustable elastomeric properties and good biodegradability. Despite the advances in 3D printing absorbable stents, there are still several challenges that remain for future research to offer full functionality and make their clinical application possible [5].
Figure 2: A workflow for manufacturing and testing bioresorbable 3D printed airway stents [5].
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