Laser-Treated Surfaces for VADs: From Inert Titanium to Potential Biofunctional Materials

Abstract

Objective. Laser-treated surfaces for ventricular assist devices. Impact Statement. This work has scientific impact since it proposes a biofunctional surface created with laser processing in bioinert titanium. Introduction. Cardiovascular diseases are the world’s leading cause of death. An especially debilitating heart disease is congestive heart failure. Among the possible therapies, heart transplantation and mechanical circulatory assistance are the main treatments for its severe form at a more advanced stage. The development of biomaterials for ventricular assist devices is still being carried out. Although polished titanium is currently employed in several devices, its performance could be improved by enhancing the bioactivity of its surface. Methods. Aiming to improve the titanium without using coatings that can be detached, this work presents the formation of laser-induced periodic surface structures with a topology suitable for cell adhesion and neointimal tissue formation. The surface was modified by femtosecond laser ablation and cell adhesion was evaluated in vitro by using fibroblast cells. Results. The results indicate the formation of the desired topology, since the cells showed the appropriate adhesion compared to the control group. Scanning electron microscopy showed several positive characteristics in the cells shape and their surface distribution. The in vitro results obtained with different topologies point that the proposed LIPSS would provide enhanced cell adhesion and proliferation. Conclusion. The laser processes studied can create new interactions in biomaterials already known and improve the performance of biomaterials for use in ventricular assist devices.

Biofunctionalization of surfaces to minimize undesirable effects in cardiovascular assistance devices

“…6,7 Since 1980, researchers and manufacturers VAD have incentive the development of new biomaterials and surface treatments for circulatory assistance applications; no doubt the surface modification processes can minimize thrombogenic effects on the blood, increasing the durability of an implant and the patient's life expectancy. 4,[6][7][8] The literature contains several terms that describe the hematological response to sintered titanium, such as pseudoneointima, neointimal tissue, and pannus of endothelial origin, but are not precisely defined by histological verification. In general, investigators have reported the presence of these structures as a combination of endothelial cells, fibroblasts or myofibroblasts, platelets, red blood cells, macrophages, and extracellular matrix.…”

“…9 Since then, different modification processes have been tested, such as HeartMate® I with extruded polyurethane (PU), HeartMate II and III with sintered microspheres, Evaheart® with methacryloyphosphorylcholine (MPC) polymer, Carmeda® with heparin coating, and VentrAssist® with diamond-like carbon (DLC) coating. 8,[10][11][12][13][14] The properties of the DLC coating provide high mechanical resistance, high hardness, low coefficient of friction, chemical inertia, electrical insulating characteristic, and biocompatible substrate surface, among other characteristics capable of improving results of interaction with blood. 5 The incorporation of silver nanoparticles, for example, makes DLC bactericidal and ideal for a hospital surgical environment.…”

“…For components that perform a static function, the formation of a well-adhered and thromboresistant neointimal layer is preferable. 2,4,8 Both hypotheses are considered promising to improve the hemodynamic compatibility of a VAD under development at Dante Pazzanese Institute of Cardiology (IDPC). The surface modification able to minimize blood clotting, both by the absence of contact and through thromboresistant neointimal lining, was evaluated in vivo without the addition of anticoagulant drugs for a minimum and sufficient period to demonstrate the results of interaction hemodynamics.…”

“…Since 1980, researchers and manufacturers VAD have incentive the development of new biomaterials and surface treatments for circulatory assistance applications; no doubt the surface modification processes can minimize thrombogenic effects on the blood, increasing the durability of an implant and the patient's life expectancy 4,6–8 …”

“…Since then, different modification processes have been tested, such as HeartMate® I with extruded polyurethane (PU), HeartMate II and III with sintered microspheres, Evaheart® with methacryloyphosphorylcholine (MPC) polymer, Carmeda® with heparin coating, and VentrAssist® with diamond‐like carbon (DLC) coating 8,10–14 …”