Biomimetic Electrospun Fibers for Peripheral Nervous System Repair.

Peripheral Nerve Regeneration;Tissue Scaffold;Electrospinning;Biomedical Engineering;Engineering;Biomedical Engineering

Leach, Michelle K.Stegemann, Jan Philip ;

University of Michigan

关键词: Peripheral Nerve Regeneration;    Tissue Scaffold;    Electrospinning;    Biomedical Engineering;    Engineering;    Biomedical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/97987/mkleach_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Endogenous peripheral nerve regeneration is a slow and error-prone process, and injury to the peripheral nervous system is a significant cause of permanent disability. One promising approach to improving these outcomes is the use of artificial nerve conduits. The primary goal of this dissertation was to develop an artificial nerve conduit that outperformed the current gold standard, the autograft. The design approach was to mimic the internal microenvironment of native nerve physically and chemically, using aligned electrospun fibers modified with polypeptides to accelerate growth of regenerating neurites. In order to evaluate this candidate material however, it was necessary to develop a sufficiently rigorous in vitro system to partially predict how nanofibers could influence regenerating neurons in vivo. Three steps to this system process include electrospinning nanofibers, culturing neurons nanofibers, and assessing neuronal behavior, the first and third of which remained inefficient and irreproducible.Critical variables of electrospinning poly-L-lactide (PLLA) nanofibers were systematically investigated.A protocol to electrospin highly aligned nanofibers reproducibly was developed.We found that the distance between the spinneret tip and collector, decreasing solvent volatility, and concentrating the electric field with an aluminum sheet on the spinneret greatly improved density and alignment of electrospun nanofibers. To quantify the developmental response of neurons to nanofiber topography, a process was developed to analyze microscopic images of neurons using MetaMorph software and a custom-designed algorithm developed in MATLAB.The system was verified against analysis by hand and increased the speed of morphological analysis of neurons from 2 weeks to less than a day, roughly 90%.The peptide fragment IKVAV, when bound to nanofibers, was found to increase the speed of neurite growth in vitro compared to unbound nanofibers.As a result, IKVAV-bound nanofibers were incorporated into conduits and implanted into a gap in the sciatic nerve of Lewis rats. IKVAV-modified fibers supported regeneration, producing detectable nerve conduction after only six weeks of implantation, but underperformed autografts. Together, these results show that electrospun fibers can be reproducibly aligned, covalently bound, and used to promote peripheral nerve regeneration in vivo.