Search for Electrospun Nanofiber Materials Matching The Mechanical Properties of Native Aortic Valve

Abstract

Abstract-Porous electrospun nanofiber materials are very promising as matrixes for heart valve tissue engineering. The perfect material for this purpose has to be both mechanically strong and deformable at the same time.Materials from gelatin, polyurethane (PUR), polylactic acid (PLA) and polycaprolactone (PCL) made in several density variants were analyzed using uniaxial tensile tests and compared to mechanical properties of porcine aortic valve (AV) leaflets in radial and circumferential directions.In circumferential direction modulus of elasticity (E) of AV is 9.7±1.3MPa and -1.0±0.2MPa in radial. Ultimate strain and stress is 44.8±5.9% and 2.3±0.6MPa in circumferential and 95.6±31.4% and 0.5±0.2MPa in radial direction for AV. Closest of the materials to native AV in circumferential direction was PUR with area density 6.2 g/m 2 showing E of 3.9±0.5 MPa, ultimate stress and strain -5.3±1.68MPa and 141.8±43.9% respectively. Closest to radial direction was gelatin with area density 5.7 g/m 2 showing E of 0.64±0.14 MPa, ultimate stress and strain -0.38±0.05MPa and 82.53±10.20% respectively.Native AV leaflets have a non-linear and anisotropic response to stress in uniaxial tensile tests. To model their mechanical properties we suggest using a combined material made of gelatin and PUR with their fibbers predominantly orientated in perpendicular directions.

Valve Tissue Engineering with Living Absorbable Threads

“…Since the authors of this article have previous experience with production and processing of PCL nanofibers (see Figure ), this will be used to illustrate general problems related to the fabrication of nanofibers. First of all, the nanofibers patches are much weaker in comparison to native tissues, for example, elasticity (E), ultimate stress (σ M), and ultimate strain (σ X) for PCL nanofibers patch (15.7 g m −2 ) are 1.3 ± 0.2 MPa, 0.3 ± 0.05 MPa, and 37.9% ± 2.46% respectively, while for porcine aortic valve the values reach 9.7 ± 1.3 MPa, 2.3 ± 0.6 MPa, 44.8% ± 5.9%, respectively . Additionally, for anisotropic PCL mats the elasticity can be significantly lower (even sometimes being a few folds lower in magnitude) on the direction perpendicular to the alignment direction.…”

“…The electrospun and jet‐sprayed fibers have already been proved to have the potential for engineering a functional heart‐valve, but the final goal of delivering functional structure for clinical applications has not been accomplished yet. Perhaps it is due to limitation of nanofibers materials and its fabrication process.…”

Optimal Mechanical Parameters for Structural Components of Heart Valve Bioprostheses and Selection of a Matching Substitute Material. Summary of the Doctoral Thesis

“…Flexion fatigue is thought to be one of the main causes of leaflet rupture [36,42]. Arcidiacono and colleague [1] with means of computer modeling have shown that even the slightest differences in rigidity of valve leaflets have an impact on the dynamics of valve opening and closure, stressing the importance of leaflet mechanical properties homogeneity within one valve. All these previous studies point out that increased leaflet rigidity characterized by higher modulus of elasticity values may have significant impact on bioprosthesis longevity and hemodynamic properties.…”