Aligned Protein–Polymer Composite Fibers Enhance Nerve Regeneration: A Potential Tissue‐Engineering Platform

Sustained release of proteins from aligned polymeric fibers holds great potential in tissue-engineering applications. These protein-polymer composite fibers possess high surface-area-to-volume ratios for cell attachment, and can provide biochemical and topographic cues to enhance tissue regeneration. Aligned biodegradable polymeric fibers that encapsulate human glial cell-derived neurotrophic factor (GDNF, 0.13 wt%) were fabricated via electrospinning a copolymer of caprolactone and ethyl ethylene phosphate (PCLEEP) with GDNF. The protein was randomly dispersed throughout the polymer matrix in aggregate form, and released in a sustained manner for up to two months. The efficacy of these composite fibers was tested in a rat model for peripheral nerve-injury treatment. Rats were divided into four groups, receiving either empty PCLEEP tubes (control); tubes with plain PCLEEP electrospun fibers aligned longitudinally (EF-L) or circumferentially (EF-C); or tubes with aligned GDNF-PCLEEP fibers (EF-L-GDNF). After three months, bridging of a 15 mm critical defect gap by the regenerated nerve was observed in all the rats that received nerve conduits with electrospun fibers, as opposed to 50% in the control group. Electrophysiological recovery was seen in 20%, 33%, and 44% of the rats in the EF-C, EF-L, and EF-L-GDNF groups respectively, whilst none was observed in the controls. This study has demonstrated that, without further modification, plain electrospun fibers can help in peripheral nerve regeneration; however, the synergistic effect of an encapsulated growth factor facilitated a more significant recovery. This study also demonstrated the novel use of electrospinning to incorporate biochemical and topographical cues into a single implant for in vivo tissue-engineering applications.

[1]  Anthony Atala,et al.  Controlled fabrication of a biological vascular substitute. , 2006, Biomaterials.

[2]  G Lundborg,et al.  Bioartificial nerve graft for bridging extended nerve defects in rat sciatic nerve based on resorbable guiding filaments. , 2000, Scandinavian journal of plastic and reconstructive surgery and hand surgery.

[3]  T. Crawford,et al.  Glial Cell Line-Derived Neurotrophic Factor Alters Axon Schwann Cell Units and Promotes Myelination in Unmyelinated Nerve Fibers , 2003, The Journal of Neuroscience.

[4]  Giulio Cossu,et al.  Electrospun degradable polyesterurethane membranes: potential scaffolds for skeletal muscle tissue engineering. , 2005, Biomaterials.

[5]  S. Ramakrishna,et al.  Electrospinning of nano/micro scale poly(L-lactic acid) aligned fibers and their potential in neural tissue engineering. , 2005, Biomaterials.

[6]  H. Buettner,et al.  Oriented Schwann Cell Monolayers for Directed Neurite Outgrowth , 2004, Annals of Biomedical Engineering.

[7]  N. Déglon,et al.  Comparative study of GDNF delivery systems for the CNS: polymer rods, encapsulated cells, and lentiviral vectors. , 2003, Journal of controlled release : official journal of the Controlled Release Society.

[8]  R. Eberhart,et al.  Poly(L‐Lactide) microfilaments enhance peripheral nerve regeneration across extended nerve lesions , 2003, Journal of neuroscience research.

[9]  K. Conant,et al.  Transplanted neural stem cells promote axonal regeneration through chronically denervated peripheral nerves , 2004, Experimental Neurology.

[10]  Surya K Mallapragada,et al.  Synergistic effects of micropatterned biodegradable conduits and Schwann cells on sciatic nerve regeneration , 2004, Journal of neural engineering.

[11]  A. Grosberg,et al.  Rational Design of Contact Guiding, Neurotrophic Matrices for Peripheral Nerve Regeneration , 2003, Annals of Biomedical Engineering.

[12]  Kwangsok Kim,et al.  Incorporation and controlled release of a hydrophilic antibiotic using poly(lactide-co-glycolide)-based electrospun nanofibrous scaffolds. , 2004, Journal of controlled release : official journal of the Controlled Release Society.

[13]  R. Zhuo,et al.  Preparation and characterization of poly(D,L‐lactide‐co‐ethylene methyl phosphate) , 1998 .

[14]  Rajiv Midha,et al.  Peripheral nerve regeneration through a synthetic hydrogel nerve tube. , 2005, Restorative neurology and neuroscience.

[15]  M. Akagi,et al.  Nerve regeneration along collagen filament and the presence of distal nerve stump , 2004, Neurological research.

[16]  Lars Montelius,et al.  Axonal outgrowth on nano-imprinted patterns. , 2006, Biomaterials.

[17]  P. Francel,et al.  Regeneration of rat sciatic nerve across a LactoSorb bioresorbable conduit with interposed short-segment nerve grafts. , 2003, Journal of neurosurgery.

[18]  Micropatterned polymer substrates control alignment of proliferating Schwann cells to direct neuronal regeneration , 2005 .

[19]  G. Lundborg,et al.  Bridging defects in nerve continuity: influence of variations in synthetic fiber composition , 1999, Journal of materials science. Materials in medicine.

[20]  Lixin Yang,et al.  Biodegradable electrospun fibers for drug delivery. , 2003, Journal of controlled release : official journal of the Controlled Release Society.

[21]  Richard Tuli,et al.  Multilineage differentiation of human mesenchymal stem cells in a three-dimensional nanofibrous scaffold. , 2005, Biomaterials.

[22]  Jennifer S Wayne,et al.  Mechanical properties and cellular proliferation of electrospun collagen type II. , 2004, Tissue engineering.

[23]  Jianjun Guan,et al.  Microintegrating smooth muscle cells into a biodegradable, elastomeric fiber matrix. , 2006, Biomaterials.

[24]  David S. Jones,et al.  Chlorhexidine release from poly(ε-caprolactone) films prepared by solvent evaporation , 1996 .

[25]  B. Hsiao,et al.  Development of a nanostructured DNA delivery scaffold via electrospinning of PLGA and PLA-PEG block copolymers. , 2003, Journal of controlled release : official journal of the Controlled Release Society.

[26]  John Layman,et al.  Release of tetracycline hydrochloride from electrospun poly(ethylene-co-vinylacetate), poly(lactic acid), and a blend. , 2002, Journal of controlled release : official journal of the Controlled Release Society.

[27]  R. Eberhart,et al.  Laminin-coated poly(L-lactide) filaments induce robust neurite growth while providing directional orientation. , 2000, Journal of biomedical materials research.

[28]  G. Keilhoff,et al.  Tissue engineering of peripheral nerves: Epineurial grafts with application of cultured Schwann cells , 2003, Microsurgery.

[29]  R. Tuan,et al.  A three-dimensional nanofibrous scaffold for cartilage tissue engineering using human mesenchymal stem cells. , 2005, Biomaterials.

[30]  H. Sawada,et al.  Peripheral nerve regeneration by transplantation of bone marrow stromal cell-derived Schwann cells in adult rats. , 2004, Journal of neurosurgery.

[31]  Jianwei Hou,et al.  Acceleration effect of basic fibroblast growth factor on the regeneration of peripheral nerve through a 15-mm gap. , 2003, Journal of biomedical materials research. Part A.

[32]  Seeram Ramakrishna,et al.  Electrospun nanofiber fabrication as synthetic extracellular matrix and its potential for vascular tissue engineering. , 2004, Tissue engineering.

[33]  P. Aebischer,et al.  Simultaneous GDNF and BDNF application leads to increased motoneuron survival and improved functional outcome in an experimental model for obstetric brachial plexus lesions. , 2002, Plastic and reconstructive surgery.

[34]  David L Kaplan,et al.  Human bone marrow stromal cell responses on electrospun silk fibroin mats. , 2004, Biomaterials.

[35]  S. Frostick,et al.  Schwann cells, neurotrophic factors, and peripheral nerve regeneration , 1998, Microsurgery.

[36]  S. Deb,et al.  Bioresorbable Glass Fibres Facilitate Peripheral Nerve Regeneration , 2005, Journal of hand surgery.

[37]  Patrick Aebischer,et al.  Glial cell line‐derived neurotrophic factor released by synthetic guidance channels promotes facial nerve regeneration in the rat , 2002, Journal of neuroscience research.

[38]  Thomas Stieglitz,et al.  Morphologic and functional evaluation of peripheral nerve fibers regenerated through polyimide sieve electrodes over long-term implantation. , 2002, Journal of biomedical materials research.

[39]  F. Stang,et al.  Structural parameters of collagen nerve grafts influence peripheral nerve regeneration. , 2005, Biomaterials.

[40]  G. Terenghi,et al.  Peripheral nerve regeneration and neurotrophic factors , 1999, Journal of anatomy.

[41]  C. Booth,et al.  Preparation and characterization of poly(ε-caprolactone) polymer blends for the delivery of proteins , 1995 .

[42]  Hongliang Jiang,et al.  Preparation and characterization of ibuprofen-loaded poly(lactide-co-glycolide)/poly(ethylene glycol)-g-chitosan electrospun membranes , 2004, Journal of biomaterials science. Polymer edition.

[43]  F. Rodrı́guez,et al.  FK506 enhances regeneration of axons across long peripheral nerve gaps repaired with collagen guides seeded with allogeneic Schwann cells , 2004, Glia.

[44]  Xavier Navarro,et al.  Magnetically Aligned Collagen Gel Filling a Collagen Nerve Guide Improves Peripheral Nerve Regeneration , 1999, Experimental Neurology.

[45]  Kam W Leong,et al.  Sustained release of proteins from electrospun biodegradable fibers. , 2005, Biomacromolecules.

[46]  David J. Mooney,et al.  Polymeric Growth Factor Delivery Strategies for Tissue Engineering , 2003, Pharmaceutical Research.

[47]  I. Strömberg,et al.  Implantation of Bioactive Growth Factor-Secreting Rods Enhances Fetal Dopaminergic Graft Survival, Outgrowth Density, and Functional Recovery in a Rat Model of Parkinson's Disease , 2000, Experimental Neurology.

[48]  R. Eberhart,et al.  Synergistic improvements in cell and axonal migration across sciatic nerve lesion gaps using bioresorbable filaments and heregulin-beta1. , 2004, Journal of biomedical materials research. Part A.

[49]  Wan-Ju Li,et al.  Biological response of chondrocytes cultured in three-dimensional nanofibrous poly(ϵ-caprolactone) scaffolds† , 2003 .