Blood Cell Adhesion on a Polymeric Heart Valve Leaflet Processed Using Magnetic Abrasive Finishing

Abstract

Polymeric heart valves have the potential to improve hemodynamic function without the complications associated with bioprosthetic and mechanical heart valves, but they have exhibited issues that need to be addressed including calcification, hydrolysis, low durability, and the adhesion of blood cells on the valves. These issues are attributed to the valves' material properties and surface conditions in addition to the hemodynamics. To overcome these issues, a new stentless, single-component trileaflet polymeric heart valve with engineered leaflet surface texture was designed, and prototypes were fabricated from a simple polymeric tube. The single-component structure features a trileaflet polymeric valve and conduit that are made of a single tube component to eliminate complications possibly caused by the interaction of multiple materials and components. This paper focuses on the leaflet surface modification and the effects of leaflet surface texture on blood cell adhesion to the leaflet surface. Silicone rubber was chosen as the working material. A magnetic abrasive finishing (MAF) process was used to alter the inner surface of the tubular mold in contact with the silicone leaflets during the curing process. It was hypothesized that the maximum profile height Rz of the mold surface should be smaller than the minimum platelet size of 1 μm to prevent platelets (1–3 μm in diameter) from becoming lodged between the peaks. Cell adhesion studies using human whole blood flushed at low shear stresses over leaflet surfaces with six different textures showed that adhesion of the platelets and red blood cells is greatly influenced by both surface roughness and lay. Leaflets replicated from MAF-produced mold surfaces consisting of short asperities smaller than 1 μm reduced blood cell adhesion and aggregation. Cell adhesion studies also found that either mold or leaflet surface roughness can be used as a measure of cell adhesion.

Physical Characterization and Platelet Interactions under Shear Flows of a Novel Thermoset Polyisobutylene-based Co-polymer

“…The surface roughness reported here may be mitigated by refining the manufacturing process . Platelet adhesion on other valve polymer candidates (such as thermoplastic polyurethane, PCU, and silicone) has been reduced by surface smoothing of thermoplastic polyurethane with argon plasma treatment, transfer of a wave-like groove pattern to PCU tubes from a centrifugal casting mold, and magnetic abrasive finishing of silicone rubber . Optimization of xSIBS roughness using similar techniques will be explored in the future.…”

“…68 Platelet adhesion on other valve polymer candidates (such as thermoplastic polyurethane, PCU, and silicone) has been reduced by surface smoothing of thermoplastic polyurethane with argon plasma treatment, 69 transfer of a wave-like groove pattern to PCU tubes from a centrifugal casting mold, 70 and magnetic abrasive finishing of silicone rubber. 71 Optimization of xSIBS roughness using similar techniques will be explored in the future. The role of microstructured surfaces in mitigation of platelet adhesion has been demonstrated on poly(lactic-co-glycolic-acid) (PLGA) films, 72 and the generation of microstructures has been implemented via slow injection molding for poly(styreneblock-isoprene-block-styrene) (SIS30), which is structurally similar to SIBS.…”

Preliminary in-silico analysis of vascular graft implantation configuration and surface modification

“…The choice for silicon as a lining for the PTFE conduit was based on previous work done by Boggs et al Their work shows a significantly lower platelet adhesion to surface-finished silicon, using magnetic abrasive technique achieving sub micrometer peak to valley surface roughness with decreased thrombogenicity 27 . While the unlined surface, without silicon, shows higher platelet adhesion and activation 28 .…”

“…However, the activation will start after the platelet firmly adheres to the surface of the conduit releasing factors that will promote recruitment of further platelets and release factors that will activate the clotting cascade. We hypothesize that the smooth surface will decrease the irreversible adhesion of platelets to the surface and that curtails the starting of the clotting process 24 , 27 .…”

Magnetic field-assisted finishing processes: from bibliometric analysis to future trends

“…Magnetic field-assisted finishing can smooth surfaces [ 8 , 9 ], deburr workpiece edges [ 10 , 11 ], and alter surface hydrodynamic properties (e.g., wettability [ 12 ] and adhesion [ 13 ]), tribological properties (e.g., wear [ 14 , 15 ] and friction [ 16 ]), and optical properties [ 17 ]. It has been successfully applied in aerospace [ 18 , 19 ], electronics [ 20 ], textile [ 21 ], military [ 22 ], cosmetics [ 23 ], and the optics industry [ 24 ], improving product longevity and functionality.…”