A means for targeting therapeutics to peripheral nervous system neurons with axonal damage.
ABSTRACT Delivery of biological therapeutics to motor and dorsal root ganglion neurons remains a major hurdle in the development of treatments for a variety of neurological processes, including peripheral nerve injury, pain, and motor neuron diseases. Because nerve cell bodies are important in initiating and controlling axonal regeneration, targeted delivery is an appealing strategy to deliver therapeutic proteins after peripheral nerve injury.
Tet1 is a 12-aa peptide, isolated through phage display that is selected for tetanus toxin C fragment-like binding properties. In this study, we surveyed its uptake and retrograde transport using compartmented cultures and sciatic nerve injections. We then characterized the time course of this delivery. Finally, to confirm the retrograde transport involvement, a colchicine pretreatment was performed. We also performed competitive binding studies between Tet1 and a recombinant tetanus toxin C fragment using recombinant tetanus toxin C fragment enzyme-linked immunosorbent assay.
We were able to demonstrate efficient uptake and retrograde axonal transport of the Tet1 peptide in vitro and in vivo. Intraneural colchicine pretreatment partially blocked fluorescence detection in the spinal cord, revealing a retrograde axonal transport mechanism. Finally, a competitive enzyme-linked immunosorbent assay experiment revealed Tet1-specific binding to the recombinant tetanus toxin C fragment axon terminal trisialogangliosides receptor.
These properties of Tet1 can be applied to the development of therapeutic viral vectors and fusion proteins for neuronal targeting and enhanced spinal cord delivery in the treatment of nerve regeneration, neuroprotection, analgesia, and spasticity. Small peptides can be easily fused to larger proteins without significantly modifying their function and can be used to alter the binding and uptake properties of these proteins.
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ABSTRACT: ObjectThe purpose was to investigate the effects of local tetanus toxin (TeTx) application on sciatic nerve regeneration following a rat model of transection injury.Methods After both sciatic nerves were transected and repaired with three epineural sutures, 12 male Wistar albino rats were divided into two groups. 0.25 ml (2.5 flocculation units) TeTx was injected into a piece of absorbable gelatin sponge in TeTx group. In controls, 0.25 ml saline injected. Assessments were performed by using climbing degrees, compound muscle action potentials (CMAPs) and histological parameters (axon number and axonal diameter) 12th week.ResultsCMAPs amplitudes were 11.6 ± 4.7 mV and 1.4 ± 1.3 mV in gastrocnemius and interdigital muscles in TeTx group (5.8 ± 2.4 mV and 0.2 ± 0.1 mV, P < 0.05). Climbing degrees were significantly different (61.6 ± 1.7 vs. 38.3 ± 2.6, P < 0.05). Total axon numbers were higher (1341.1 ± 57.3 vs. 877.5 ± 34.9, P < 0.05) and the mean axon diameter was smaller (4.2 ± 2.1 vs. 2.5 ± 1.9, P < 0.05) in the TeTx group.Conclusion This preliminary study firstly demonstrated the effectiveness of TeTx on nerve repair in experimental sciatic rat model based on functional, electromyographic and histological parameters. © 2014 Wiley Periodicals, Inc. Microsurgery, 2014.Microsurgery 03/2014; 34(5). DOI:10.1002/micr.22249 · 1.62 Impact Factor
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ABSTRACT: The blood-brain barrier acts as a physical barrier that prevents free entry of blood-derived substances, including those intended for therapeutic applications. The development of molecular Trojan horses is a promising drug targeting technology that allows for non-invasive delivery of therapeutics into the brain. This concept relies on the application of natural or genetically engineered proteins or small peptides, capable of specifically ferrying a drug-payload that is either directly coupled or encapsulated in an appropriate nanocarrier, across the blood-brain barrier via receptor-mediated transcytosis. Specifically, in this process the nanocarrier-drug system ("Trojan horse complex") is transported transcellularly across the brain endothelium, from the blood to the brain interface, essentially trailed by a native receptor. Naturally, only certain properties would favor a receptor to serve as a transporter for nanocarriers, coated with appropriate ligands. Here we briefly discuss brain microvascular endothelial receptors that have been explored until now, highlighting molecular features that govern the efficiency of nanocarrier-mediated drug delivery into the brain.Pharmaceutics 12/2014; 6(4):557-583. DOI:10.3390/pharmaceutics6040557
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ABSTRACT: Objective: The aim of this study was to determine whether platelet-rich plasma has a regenerative effect on a sciatic nerve injury model in rats. Methods: A sciatic nerve cut model was created in 24 nerves of 12 rats. All nerves were repaired with epineural sutures by the same surgeon. Rats were randomly divided into two groups; platelet-rich plasma was applied to the injury site in the platelet-rich plasma group and saline only to the same area in the control group. Motor and electromyographic assessments were performed at the end of 12th postoperative week and all rats were euthanized for histological specimens. Results: Motor recovery was significantly better in the platelet-rich plasma group than the control group. The differences in electromyographic and histomorphometric findings between the groups were significant (p<0.05). Conclusion: Our experimental study demonstrated positive effects of platelet-rich plasma on nerve regeneration.acta orthopaedica et traumatologica turcica 01/2014; 48(4):449-454. · 0.55 Impact Factor