-
Experimental Neurology Sep 2016Compared to the central nervous system (CNS), peripheral nerves have a remarkable ability to regenerate and remyelinate. This regenerative capacity to a large extent is... (Review)
Review
Compared to the central nervous system (CNS), peripheral nerves have a remarkable ability to regenerate and remyelinate. This regenerative capacity to a large extent is dependent on and supported by Schwann cells, the myelin-forming glial cells of the peripheral nervous system (PNS). In a variety of paradigms, Schwann cells are critical in the removal of the degenerated tissue, which is followed by remyelination of newly-regenerated axons. This unique plasticity of Schwann cells has been the target of myelin repair strategies in acute injuries and chronic diseases, such as hereditary demyelinating neuropathies. In one approach, the endogenous regenerative capacity of Schwann cells is enhanced through interventions such as exercise, electrical stimulation or pharmacological means. Alternatively, Schwann cells derived from healthy nerves, or engineered from different tissue sources have been transplanted into the PNS to support remyelination. These transplant approaches can then be further enhanced by exercise and/or electrical stimulation, as well as by the inclusion of biomaterial engineered to support glial cell viability and neurite extension. Advances in our basic understanding of peripheral nerve biology, as well as biomaterial engineering, will further improve the functional repair of myelinated peripheral nerves.
Topics: Animals; Demyelinating Diseases; Humans; Myelin Sheath; Nerve Regeneration; Neuroglia; Peripheral Nerves
PubMed: 27079997
DOI: 10.1016/j.expneurol.2016.04.007 -
Journal of Neurophysiology Sep 2018In the first section, this historical review describes endeavors to develop the method for recording normal nerve impulse traffic in humans, designated microneurography.... (Review)
Review
In the first section, this historical review describes endeavors to develop the method for recording normal nerve impulse traffic in humans, designated microneurography. The method was developed at the Department of Clinical Neurophysiology of the Academic Hospital in Uppsala, Sweden. Microneurography involves the impalement of a peripheral nerve with a tungsten needle electrode. Electrode position is adjusted by hand until the activity of interest is discriminated. Nothing similar had previously been tried in animal preparations, and thus the large number of preceding studies that recorded afferent activity in other mammals did not offer pertinent methodological guidance. For 2 years, the two scientists involved in the research impaled their own nerves with electrodes to test various kinds of needles and explore different neural systems, all the while carefully watching for signs of nerve damage. Temporary paresthesiae were common, whereas enduring sequelae never followed. Single-unit impulse trains could be discriminated, even those originating from unmyelinated fibers. An explanation for the discrimination of unitary impulses using a coarse electrode is inferred based on the electrical characteristics of the electrode placed in the flesh and the impulse shapes, as discussed in the second section of this paper. Microneurography and the microstimulation of single afferents, combined with psychophysical methods and behavioral tests, have generated new knowledge particularly regarding four neural systems, namely the proprioceptive system, the cutaneous mechanoreceptive system, the cutaneous nociceptive system, and the sympathetic efferent system to skin structures and muscular blood vessels. Examples of achievements based on microneurography are presented in the final section.
Topics: Action Potentials; Electrophysiology; History, 20th Century; Humans; Microelectrodes; Nerve Fibers, Myelinated; Nerve Fibers, Unmyelinated; Peripheral Nerves
PubMed: 29924706
DOI: 10.1152/jn.00933.2017 -
Journal of Biomedical Optics May 2022Means for quantitation of myelinated fibers in peripheral nerve may guide diagnosis and clinical decision making in management of peripheral nerve disorders. Multiphoton...
SIGNIFICANCE
Means for quantitation of myelinated fibers in peripheral nerve may guide diagnosis and clinical decision making in management of peripheral nerve disorders. Multiphoton microscopy techniques such as the third-harmonic generation enable label-free in vivo imaging of peripheral nerves.
AIM
Develop a multiphoton microscope based on a custom high-power infrared fiber laser for label-free imaging of peripheral nerve.
APPROACH
A cost-effective multiphoton microscope employing a single fiber laser source at 1300 nm was designed and used for stain-free multicolor imaging of murine and human peripheral nerve.
RESULTS
Second-harmonic generation signal from collagen centered about 650-nm delineated neural connective tissue, whereas third-harmonic general signal centered about 433-nm delineated myelin and other lipids. In sciatic nerve from transgenic reporter mice expressing yellow fluorescent protein within peripheral neurons, three-photon-excitation with emission peak at 527-nm delineated axoplasm. The signal obtained from unlabeled axially sectioned samples was adequate for segmentation of myelinated fibers using commercial image processing software. In unlabeled whole mount specimens, imaging depths over 100-μm were achieved.
CONCLUSIONS
A multiphoton microscope powered by a fiber laser enables stain-free histomorphometry of mammalian peripheral nerve. The simplicity of the microscope design carries potential for clinical translation to inform decision making in peripheral nerve disorders.
Topics: Animals; Collagen; Coloring Agents; Mammals; Mice; Mice, Transgenic; Microscopy; Microscopy, Fluorescence, Multiphoton; Myelin Sheath; Sciatic Nerve
PubMed: 35568795
DOI: 10.1117/1.JBO.27.5.056501 -
International Journal of Molecular... Oct 2021Endothelial cells acquire different phenotypes to establish functional vascular networks. Vascular endothelial growth factor (VEGF) signaling induces endothelial... (Review)
Review
Endothelial cells acquire different phenotypes to establish functional vascular networks. Vascular endothelial growth factor (VEGF) signaling induces endothelial proliferation, migration, and survival to regulate vascular development, which leads to the construction of a vascular plexuses with a regular morphology. The spatiotemporal localization of angiogenic factors and the extracellular matrix play fundamental roles in ensuring the proper regulation of angiogenesis. This review article highlights how and what kinds of extracellular environmental molecules regulate angiogenesis. Close interactions between the vascular and neural systems involve shared molecular mechanisms to coordinate developmental and regenerative processes. This review article focuses on current knowledge about the roles of angiogenesis in peripheral nerve regeneration and the latest therapeutic strategies for the treatment of peripheral nerve injury.
Topics: Angiogenesis Inducing Agents; Animals; Cell Proliferation; Endothelial Cells; Extracellular Matrix; Humans; Neovascularization, Physiologic; Nerve Regeneration; Peripheral Nerve Injuries; Peripheral Nerves; Signal Transduction; Vascular Endothelial Growth Factors
PubMed: 34681829
DOI: 10.3390/ijms222011169 -
International Journal of Molecular... Jan 2017Peripheral nerve regeneration is a complicated process highlighted by Wallerian degeneration, axonal sprouting, and remyelination. Schwann cells play an integral role in... (Review)
Review
Peripheral nerve regeneration is a complicated process highlighted by Wallerian degeneration, axonal sprouting, and remyelination. Schwann cells play an integral role in multiple facets of nerve regeneration but obtaining Schwann cells for cell-based therapy is limited by the invasive nature of harvesting and donor site morbidity. Stem cell transplantation for peripheral nerve regeneration offers an alternative cell-based therapy with several regenerative benefits. Stem cells have the potential to differentiate into Schwann-like cells that recruit macrophages for removal of cellular debris. They also can secrete neurotrophic factors to promote axonal growth, and remyelination. Currently, various types of stem cell sources are being investigated for their application to peripheral nerve regeneration. This review highlights studies involving the stem cell types, the mechanisms of their action, methods of delivery to the injury site, and relevant pre-clinical or clinical data. The purpose of this article is to review the current point of view on the application of stem cell based strategy for peripheral nerve regeneration.
Topics: Animals; Cell Differentiation; Cell- and Tissue-Based Therapy; Humans; Nerve Regeneration; Peripheral Nerve Injuries; Peripheral Nerves; Schwann Cells; Stem Cell Transplantation; Stem Cells
PubMed: 28067783
DOI: 10.3390/ijms18010094 -
Seminars in Musculoskeletal Radiology Apr 2022Imaging evaluation of peripheral nerves (PNs) is challenging. Magnetic resonance imaging (MRI) and ultrasonography are the modalities of choice in the imaging assessment...
Imaging evaluation of peripheral nerves (PNs) is challenging. Magnetic resonance imaging (MRI) and ultrasonography are the modalities of choice in the imaging assessment of PNs. Both conventional MRI pulse sequences and advanced techniques have important roles. Routine MR sequences are the workhorse, with the main goal to provide superb anatomical definition and identify focal or diffuse nerve T2 signal abnormalities. Selective techniques, such as three-dimensional (3D) cranial nerve imaging (CRANI) or 3D NerveVIEW, allow for a more detailed evaluation of normal and pathologic states. These conventional pulse sequences have a limited role in the comprehensive assessment of pathophysiologic and ultrastructural abnormalities of PNs. Advanced functional MR neurography sequences, such as diffusion tensor imaging tractography or T2 mapping, provide useful and robust quantitative parameters that can be useful in the assessment of PNs on a microscopic level. This article offers an overview of various technical parameters, pulse sequences, and protocols available in the imaging of PNs and provides tips on avoiding potential pitfalls.
Topics: Cranial Nerves; Diffusion Tensor Imaging; Humans; Magnetic Resonance Imaging; Peripheral Nerves; Ultrasonography
PubMed: 35609571
DOI: 10.1055/s-0042-1742753 -
International Journal of Molecular... Aug 2020The peripheral nervous system controls the functions of sensation, movement and motor coordination of the body. Peripheral nerves can get damaged easily by trauma or... (Review)
Review
The peripheral nervous system controls the functions of sensation, movement and motor coordination of the body. Peripheral nerves can get damaged easily by trauma or neurodegenerative diseases. The injury can cause a devastating effect on the affected individual and his aides. Treatment modalities include anti-inflammatory medications, physiotherapy, surgery, nerve grafting and rehabilitation. 3D bioprinted peripheral nerve conduits serve as nerve grafts to fill the gaps of severed nerve bodies. The application of induced pluripotent stem cells, its derivatives and bioprinting are important techniques that come in handy while making living peripheral nerve conduits. The design of nerve conduits and bioprinting require comprehensive information on neural architecture, type of injury, neural supporting cells, scaffold materials to use, neural growth factors to add and to streamline the mechanical properties of the conduit. This paper gives a perspective on the factors to consider while bioprinting the peripheral nerve conduits.
Topics: Animals; Bioprinting; Humans; Induced Pluripotent Stem Cells; Peripheral Nerves; Printing, Three-Dimensional; Tissue Engineering; Tissue Scaffolds
PubMed: 32806758
DOI: 10.3390/ijms21165792 -
Trends in Cancer Dec 2020Over the past decade, several landmark reports have demonstrated that the nervous system plays an active role in cancer initiation and progression. These studies... (Review)
Review
Over the past decade, several landmark reports have demonstrated that the nervous system plays an active role in cancer initiation and progression. These studies demonstrate that ablation of specific nerve types (parasympathetic, sympathetic, or sensory) abrogates tumor growth in a tissue-specific manner. Further, many tumor types are more densely innervated than their normal tissues of origin. These striking results raise fundamental questions regarding tumor innervation, how it is initiated, and how it molecularly contributes to disease. In this review, we aim to address what is currently known about the origin of tumor-infiltrating nerves, how they may be recruited to tumors, and how their presence may give rise to aggressive disease.
Topics: Cell Transformation, Neoplastic; Cellular Reprogramming; Disease Progression; Extracellular Vesicles; Humans; Neoplasms; Neural Stem Cells; Peripheral Nerves
PubMed: 32807693
DOI: 10.1016/j.trecan.2020.07.005 -
Acta Bio-medica : Atenei Parmensis Apr 2021Muscle in vein (MIV ) conduits have gradually been employed in the last 20 years as a valuable technique in bridging peripheral nerve gaps after nerve lesions who cannot...
Muscle in vein (MIV ) conduits have gradually been employed in the last 20 years as a valuable technique in bridging peripheral nerve gaps after nerve lesions who cannot undergo a direct tension-free coaptation. The advantages of this procedure comparing to the actual benchmark (autograft) is the sparing of the donor site, and the huge availability of both components (i.e. muscle and veins). Here we present a case serie of four MIV performed at our hospital from 2018 to 2019. The results we obtained in our experi-ence confirmed its effectiveness both in nerve regeneration (as sensibility recovery) and in neuropathic pain eradication. Our positive outcomes encourage its use in selected cases of residual nerve gaps up to 30 mm.
Topics: Humans; Muscles; Nerve Regeneration; Peripheral Nerve Injuries; Peripheral Nerves; Veins
PubMed: 33944845
DOI: 10.23750/abm.v92iS1.9202 -
SLAS Technology Jun 2023Tissue-engineered nerve guidance conduits (NGCs) are a viable clinical alternative to autografts and allografts and have been widely used to treat peripheral nerve... (Review)
Review
Tissue-engineered nerve guidance conduits (NGCs) are a viable clinical alternative to autografts and allografts and have been widely used to treat peripheral nerve injuries (PNIs). Although these NGCs are successful to some extent, they cannot aid in native regeneration by improving native-equivalent neural innervation or regrowth. Further, NGCs exhibit longer recovery period and high cost limiting their clinical applications. Additive manufacturing (AM) could be an alternative to the existing drawbacks of the conventional NGCs fabrication methods. The emergence of the AM technique has offered ease for developing personalized three-dimensional (3D) neural constructs with intricate features and higher accuracy on a larger scale, replicating the native feature of nerve tissue. This review introduces the structural organization of peripheral nerves, the classification of PNI, and limitations in clinical and conventional nerve scaffold fabrication strategies. The principles and advantages of AM-based techniques, including the combinatorial approaches utilized for manufacturing 3D nerve conduits, are briefly summarized. This review also outlines the crucial parameters, such as the choice of printable biomaterials, 3D microstructural design/model, conductivity, permeability, degradation, mechanical property, and sterilization required to fabricate large-scale additive-manufactured NGCs successfully. Finally, the challenges and future directions toward fabricating the 3D-printed/bioprinted NGCs for clinical translation are also discussed.
Topics: Nerve Regeneration; Peripheral Nerves; Tissue Engineering; Biocompatible Materials
PubMed: 37028493
DOI: 10.1016/j.slast.2023.03.006