Session Overview |
Friday, May 24 |
13:30 |
The future of biodegradable metals for vascular implants : Overcoming key challenges and emerging directions
* Roger Guillory II, Joint Department of Biomedical Engineering, Medical College of Wisconsin, Marquette University , United States of America This talk will cover relevant topics surrounding the use of biodegradable metals for vascular stenting. Vascular stenting is a demanding application of biodegradable metals, and deeper understanding of material-stent performance in pre-clinical models and how they relate to current clinical performance would increase the rate of device translation to the clinic. The leading preclinical in vivo experimental models in vascular research will be covered, and hypothetical possibilities to apply large scale data analysis towards these techniques by using the critical clinical variables will be explored. Regarding clinically relevant variables and biodegradable metal performance, multiple vascular beds and their differences will be considered and compared. Work done by our research group will be shown which demonstrates how small animal vascular preclinical models can be used in parallel to current approaches, offering insight into the local inflammatory reaction and its participation in metal clearance. Current research trends will be critically evaluated in terms of clinical utility, which includes surface treatments, bioactive molecule elution, and degradation control. Finally, the application of biodegradable metals in pediatric stenting is reviewed from a research and clinical perspective, and the most important parameters surrounding engineering biodegradable metal stents for congenital heart disease will be presented. |
14:00 |
Biological Response Of Femtosecond Laser Texturing On Fe-Mn Alloys For Vascular Applications
Francesco Copes, Laboratory for Biomaterials and Bioengineering, Laval University, Canada Jacopo Fiocchi, National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy, Italy Sofia Gambaro, National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy, Italy * Sara Palladino, Laboratory for Biomaterials and Bioengineering, Laval University, Canada Chiara Bregoli, National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy, Italy Ausonio Tuissi, National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy, Italy Carlo Alberto Biffi, National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy, Italy Diego Mantovani, Laboratory for Biomaterials and Bioengineering, Laval University, Canada Femtosecond (fs) lasers (a technique that preserve the bulk properties of the treated materials) were applied on biodegradable metals to generate surface micro geometries, while avoiding the use of additional materials, chemicals and gases. Moreover, the hypothesis behind this work was that femtoseconds laser surface modifications improved cell adhesion, proliferation and migration, while impacting the metal degradation. Results show that the degradation rate of the treated Fe-Mn20 alloy decreased of approximately 50%, compared to the control. Biological analysis showed increased endothelial cells adhesion and viability on the laser-treated samples compared to the untreated ones. Finally, both hemolysis and clotting time were not affected by the fs-induced linear patterns on the surface, when compared to the polished alloy. |
14:45 |
The challenge of electropolishing biodegradable Fe-based alloys for blood-contact applications
Leticia Marin de Andrade, Lab Biomaterials & Bioengineering, Dpt Min-Met-Mat. Engineering, CR-CHU de Quebec, Laval University, Canada * Pascale Chevallier, Lab Biomaterials & Bioengineering, Dpt Min-Met-Mat. Engineering, CR-CHU de Quebec, Laval University, Canada Carlo Paternoster, Lab Biomaterials & Bioengineering, Dpt Min-Met-Mat. Engineering, CR-CHU de Quebec, Laval University, Canada Francesco Copes, Lab Biomaterials & Bioengineering, Dpt Min-Met-Mat. Engineering, CR-CHU de Quebec, Laval University, Canada Diego Mantovani, Lab Biomaterials & Bioengineering, Dpt Min-Met-Mat. Engineering, CR-CHU de Quebec, Laval University, Canada Surface finishing is essential to guarantee the clinical success of any device implanted in contact with blood. This represents a major challenge for biodegradable metals. Indeed, surface finishing processes initiate the corrosion process. Therefore, the influence of different electrolytes used for electropolishing (EP) processes was investigated, and compared to the mechanical polishing (MP) process in terms of surface composition, morphology, topography, wettability, and corrosion behavior. EP1 (ethanol, perchloric acid, and glycerol), EP2 (perchloric acid, acetic acid and glycerol), and EP3 (choline chloride and ethylene glycol) were selected as electrolytes representative for electropolishing processes. Results showed that EP2 condition displayed an overall promising electropolishing process among the other conditions tested. Indeed, it promoted a smooth, hydrophilic passivated surface with the highest O/Metal ratio, which further exhibited suitable corrosion behavior for metallic biodegradable devices. |
15:00 |
Assessing Thrombogenicity of Mg or Zn Alloyed Biometals
* Deirdre Anderson, Oregon Health & Science University, United States of America Cole Baker, Oregon Health & Science University, United States of America Jeremy Goldman, Michigan Technological University, United States of America Monica Hinds, Oregon Health & Science University, United States of America Current stent materials require extensive anticoagulant and antiplatelet therapies to prevent clotting after stent deployment. These essential medications prevent device failure, but also increase the patients’ bleeding risk and complications for future surgeries. Biodegradable metals present an opportunity for use in stents, and understanding the thrombotic potential of these materials is critical. Understanding the material’s risk of clotting will allow better prescription of anticoagulants and potentially reduce the long-term need for these medications that exist with current clinical standards. This work tested Mg alloys, Zn alloys, and a CoCr alloy in human platelet poor plasma. The metal wires were incubated with plasma for 1hr, during dynamic biological assays. For fibrin, plasma was recalcified and the generation of fibrin was measured based on an increase in turbidity. For FXIIa generation, plasma and the wire were incubated with a chromogenic substrate to observe the generation of FXIIa colorimetrically. Pure and alloyed Mg showed consistently low fibrin generation with fibrin clotting times that were slower than plasma alone. FXIIa generation was also lower in Mg samples than plasma alone. Pure and alloyed Zn wires had faster fibrin clotting times than plasma alone, but were comparable to CoCr. Additionally, Zn-0.8Cu had a significantly higher fibrin clotting time and lower FXIIa generation than pure Zn, suggesting a somewhat improved thrombogenicity than the other Zn metals. Overall, Mg and Zn alloys consistently performed better than the CoCr clinical control suggesting that both alloy types have the potential to perform equal to or better than existing biostable stents. Ongoing work is examining Fe alloys. Future work will explore thrombosis characteristics after surface modifications. |
15:15 |
In vivo urinary compatibility of Mg-Sr-Ag alloy
* Di Tie, Dongguan EONTEC. Co., Ltd., China (People's Republic of) Giyasov-Shukhrat Iskandarovich, Tashkent Medical Academy, Uzbekistan A biodegradable metallic ureteral stent with suitable mechanical properties and antibacterial activity remains a challenge. Here we reveal the scientific significance of a biodegradable Mg-Sr-Ag alloy with a favorable combination of balanced mechanical properties, adjustable indwelling time in urinary tract and evident antibacterial activity via in vivo experiments in a swine model. Both the in vitro and in vivo results demonstrated the satisfactory biocompatibility of the alloy. The stent also improved the post-operative bladder functions viewed from the urodynamic results. Our findings highlight the potential of this alloy as antibacterial biodegradable urinary implant material. |