CONICET | Buscador de Institutos y Recursos Humanos

Small-diameter vascular grafts still present a challenger in biomaterials and tissue engineering industry. Their success lies in a biomimetic structure with size and properties in the range of the natural arteries to be replaced. Natural arteries present a complex structure, formed of three layers with collagen and elastin in different percentage and orientation. This gives the arteries their unique mechanical properties. Therefore, it is important to create a vascular graft that has layers with different materials composition and orientation. Electrospinning provides a way to design vascular grafts, with a nanofibrous extra cellular matrix-like morphology. Well-aligned nanofibers were obtained by electrospinning with different collectors. However, obtaining an aligned orientation of the fibers is not so trivial for small-diameter tubular structures. In this work, we used a novel setup that separate the electric field aiming the preparation of well-aligned superficial morphology. A grounded parallel-plate collector was placed under a stainless steel rotocollector. Poly(L-lactic acid) (PLLA) was selected as an elastic high-modulus biodegradable polymer, with a mechanical behavior similar to collagen. PLLA nanofibrous vascular grafts (5 mm internal diameter) were produced. The obtained morphology was characterized by scanning electron microscopy and micrographs were processed with image analysis software. Bead-free nanofibers displayed 383 ± 103 nm mean diameter and 66 ± 26º mean angle. Electric field was modeled by using finite element software which was able to predict the observed alignment. Regular electric field promoted in random nanofiber orientation. These results appear promising for the development of vascular grafts with improved biomechanical properties.

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