Additive manufacturing of vascular stents.

Bioresorbable stents (BRS) hold great promise for the treatment of many life‐threatening luminal diseases. Tracking and monitoring of stents in vivo is critical for avoiding their malposition and inadequate expansion, which often leads to complications and stent failure. However, obtaining high X‐ray visibility of polymeric BRS has been challenging because of their intrinsic radiolucency. This study demonstrates the use of photopolymerization‐based 3D printing technique to fabricate radiopaque BRS by incorporating iodixanol, a clinical contrast agent, into a bioresorbable citrate‐based polymer ink. The successful volumetric dispersion of the iodixanol through the 3D‐printing process confers strong X‐ray visibility of the produced BRS. Following in vitro degradation, the 3D‐printed BRS embedded in chicken muscle maintains high X‐ray visibility for at least 4 weeks. Importantly, the 3D‐printed radiopaque BRS demonstrates good cytocompatibility and strong mechanical competence in crimping and expansion, which is essential for minimally invasive stent deployment. In addition, it is found that higher loading concentrations of iodixanol, e.g. 10 wt.%, results in more strut fractures in stent crimping and expansion. To conclude, this study introduces a facile strategy to fabricate radiopaque BRS through the incorporation of iodixanol in the 3D printing process, which could potentially increase the clinical success of BRS.

3D‐Printed Radiopaque Bioresorbable Stents to Improve Device Visualization

Chemical vs thermal accelerated hydrolytic degradation of 3D-printed PLLA/PLCL bioresorbable stents: Characterization and influence of sterilization

Hernia repair mesh is associated with a number of complications, including adhesions and limited mobility, due to insufficient mechanical strength and non-resorbability. Among them, visceral adhesions are one of the most serious complications of patch repair. In this study, a degradable patch with an anti-adhesive layer was prepared for hernia repair by 3D printing and electrospinning techniques using polycaprolactone (PCL), polyvinyl alcohol (PVA), and soybean peptide (SP). The study into the physicochemical properties of the patch was found that it had adequate mechanical strength requirements (16 N cm-1 ) and large elongation at break, which were superior than commercial polypropylene (PP) patches. In vivo and in vitro experiments showed that human umbilical vein endothelial cells (HUVECs) proliferated well on composite patches, and showed excellent biocompatibility with the host and little adhesion through a rat abdominal wall defect model. In conclusion, the results of this study show that composite patch can effectively reduce the occurrence of adhesions, while the addition of SP in the patch further enhances its biocompatibility. We believe that a regenerative biological patch with great potential in hernia repair provides a new strategy for the development of new biomimetic biodegradable patches. This article is protected by copyright. All rights reserved.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/mabi.202100510

Designing Double-Layer Multi-Material Composite Patch Scaffold with Adhesion Resistance for Hernia Repair.

Bioresorbable stents (BRS) are conceived to retain sufficient radial strength after implantation while releasing an antiproliferative drug in order to prevent vessel restenosis until complete resorption. Ongoing research trends involve the use of innovative manufacturing techniques to achieve thinner struts combined with optimized local drug delivery. This work presents a combination of solvent-cast direct-writing (SC-DW) and electrospinning (ES) using poly-l-lactic acid (PLLA) and poly(l-lactic-co-ɛ-caprolactone) (PLCL) as a new approach to generate everolimus-eluting BRS for cardiovascular applications. A Design of Experiment (DoE) was conducted to determine the optimal parameters to obtain a homogeneous coating with high specific surface. Manufactured stents were characterized by means of mechanical tests and scanning electron microscopy (SEM), with everolimus release in accelerated conditions quantified through High Performance Liquid Chromatography (HPLC). Drug loading was achieved either encapsulated in the struts of the stent or in an electrospun PLCL membrane covering the stent. In the former case, everolimus release was found to be insufficient, less than 3% of total drug loading after 8 weeks. In the latter, everolimus release considerably increased with respect to drug-loaded 3D-printed stents, with over 50% release in the first 6 hours of the test. In conclusion, everolimus release from PLCL-coated 3D-printed stents would match the dose and timeframe required for in vivo applications, while providing thinner struts than SC-DW drug-loaded stents. 

Solvent-cast direct-writing and electrospinning as a dual fabrication strategy for drug-eluting polymeric bioresorbable stents

Bioresorbable stents (BRS) potential in treating coronary heart disease is still to be further developed. Current trends include research with new polymeric materials, the need for thinner struts combined with appropriate mechanical properties, radiopacity and optimized local drug delivery. This work presents a novel solvent-cast direct-write (SC-DW) printing system to manufacture BRS onto a rotating cylinder with poly- l -lactic acid (PLLA) and poly( l -lactic-co- ɛ -caprolactone) (PLCL) inks. Printed stents were characterized in terms of mechanical, thermal and biological properties with human umbilical vein endothelial cells (HUVECs). Expansion assays showed that stents withstood pressures of at least 16 atm and the indirect cytotoxicity test indicated that stents were biocompatible. Polymeric inks were further modified with the addition of 3 radiopaque agents, namely iodine, triiodobenzoic acid (TIBA) and barium sulfate (BaSO 4 ) to render stents radiopaque. Subsequent characterization showed a general increase in strut thickness with respect to control PLLA or PLCL stents, which in turn resulted in higher resistance to compression. Microcomputed tomography was used to assess stents’ radiopacity, showing that TIBA and BaSO 4 -containing stents presented high X-ray attenuation values and maintained their radiopacity after 3 months incubation time.

Solvent-cast direct-writing as a fabrication strategy for radiopaque stents

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Solvent-cast direct-writing as a fabrication strategy for radiopaque stents