This work was supported by National Institutes of Health Grants K08 NS061039-01A2, the Program for Neurology Research &amp; Discovery, and The A. Alfred Taubman Medical Research Institute at the University of Michigan. This work used the Morphology and Image Analysis Core of the Michigan Diabetes Research and Training Center, funded by National Institutes of Health Grant 5P90 DK-20572 from the National Institute of Diabetes and Digestive and Kidney Diseases. The authors would like to thank Robinson Singleton and Gordon Smith (University of Utah) for their generous donation of human skin samples to support the initial development of the nociceptive biomarker immunohistochemistry technique.

Part A: Immunohistochemistry
Preparation of 96-well plate and prevention of background staining Punch skin biopsies are collected from human subjects and incubated for 12-24 hr in fixative solution (2% paraformaldehyde with 0.75 M L-Lysine solution (pH 7.4) and 0.05 mM sodium periodate) at 4 &deg;C as previously described 8. Samples are then cryoprotected in phosphate buffered saline (PBS) with 20% glycerol at 4 &deg;C for up to 1 week, embedded in mounting media optimal cutting temper...

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V., Sommer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnostic+validity+of+epidermal+nerve+fiber+densities+in+painful+sensory+neuropathies.">Diagnostic validity of epidermal nerve fiber densities in painful sensory neuropathies.</a> Muscle Nerve. 37 (1), 50-60 (2008).</li><li>Casanova-Molla, J., Morales, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Axonal+fluorescence+quantitation+provides+a+new+approach+to+assess+cutaneous+innervation.">Axonal fluorescence quantitation provides a new approach to assess cutaneous innervation.</a> J. Neurosci. 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Syst. 11 (3), 262-271 (2006).</li><li>Penna, G., Fibbi, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+benign+prostatic+hyperplasia+stromal+cells+as+inducers+and+targets+of+chronic+immuno-mediated+inflammation.">Human benign prostatic hyperplasia stromal cells as inducers and targets of chronic immuno-mediated inflammation.</a> J. Immunol. 182 (7), 4056-4064 (2009).</li><li>Lentz, S. I., Edwards, J. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitochondrial+DNA+(mtDNA)+Biogenesis:+Visualization+and+Duel+Incorporation+of+BrdU+and+EdU+Into+Newly+Synthesized+mtDNA+In+Vitro.">Mitochondrial DNA (mtDNA) Biogenesis: Visualization and Duel Incorporation of BrdU and EdU Into Newly Synthesized mtDNA In Vitro.</a> J. Histochem. Cytochem. 58 (2), 207-218 (2010).</li><li>Polydefkis, M., Hauer, P., Griffin, J. W., McArthur, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+biopsy+as+a+tool+to+assess+distal+small+fiber+innervation+in+diabetic+neuropathy.">Skin biopsy as a tool to assess distal small fiber innervation in diabetic neuropathy.</a> Diabetes Technol. Ther. 3 (1), 23-28 (2001).</li><li>Lauria, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+fibre+neuropathies.">Small fibre neuropathies.</a> Curr. Opin. Neurol. 18 (5), 591-597 (2005).</li><li>Sorensen, L., Molyneaux, L., Yue, D. 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P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidermal+nerve+fiber+density,+axonal+swellings+and+QST+as+predictors+of+HIV+distal+sensory+neuropathy.">Epidermal nerve fiber density, axonal swellings and QST as predictors of HIV distal sensory neuropathy.</a> Muscle Nerve. 29 (3), 420-427 (2004).</li><li>Navarro, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+27:+Neural+plasticity+after+nerve+injury+and+regeneration.">Chapter 27: Neural plasticity after nerve injury and regeneration.</a> Int. Rev. Neurobiol. 87, 483-505 (2009).</li></ol>

No conflicts of interest to declare.

Measurement of IENFD has been widely used to determine the degree of peripheral neuropathies 13,14. At present, the most commonly used protocol only measures the densities of nerve fibers that penetrate the basement membrane of the epidermis; it does not take into consideration axonal branching and/or morphological changes of the nerves. In addition, current IENFD analysis has not been shown to correlate IENFD with the presence of pain in PN 15.
We previously reported th...

At present, it is common practice for physicians to quantify intraepidermal nerve fiber densities, (IENFD) from skin punch biopsies, which can be used to diagnose small fiber neuropathies 3, 6-8. Biopsies are taken from the distal leg (DL), 10 cm above the lateral malleolus, and the proximal thigh (PT), 20 cm below the anterior iliac spine 9. All IENF are labeled using protein gene product 9.5 (PGP), a pan neuronal marker 10-12. At present, it is standard practice to diagnose small fiber neuropathies using IENFD determined by PGP staining with brightfield microscopy 6. Additionally, several research groups have used immunofluorescent protocols for PGP immunohistochemistry 7-9. Small fiber neuropathy is commonly associated with neuropathic pain. In order to further understand the role of IENF essential for pain processing, we developed a technique to co-label total IENF with fibers that generate pain. Nociceptive IENF, specifically A&delta; and C fibers, can be studied through the co-labeling of IENF with PGP and the nociceptive marker, tropomyosin-receptor-kinase A (Trk A) 5. Trk A is the high affinity receptor for nerve growth factor that is essential for the development of nociception. The Trk A-positive nociceptive nerve fibers are peptidergic fibers that express substance P (SP) and calcitonin gene related peptide (CGRP). Previously, Lauria and colleagues applied the double-labeling technique to study PN, co-labeling PGP-positive IENF with a nociceptive marker 10. In our previous study, we demonstrated that Trk A-positive IENF, but not Trk A-negative IENF, were upregulated in an animal model of painful diabetic neuropathy 5. This co-labeling technique provides the ability to compare quantification of nociceptive IENFD to total IENFD and the ability to study morphological changes associated with PN. The capability to visualize nociceptive IENF and compare quantification of total IENFD to nociceptive IENFD could provide objective evidence for the presence of pain, and possibly insight into the severity of pain associated with PN. This technique is also applicable to skin of animal models. In comparison to previous studies, the current protocol describes methods for 3D image analysis, creating the opportunity to avoid errors that could occur in 2D image analysis.

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		</tr>
		<tr>
			<td>10X PBS</td>
			<td>Fisher Scientific</td>
			<td>BP399-4</td>
			<td>To make up 1X PBS</td>
		</tr>
		<tr>
			<td>Image-IT FX Signal</td>
			<td>Invitrogen</td>
			<td>I36933</td>
			<td>Image-IT</td>
		</tr>
		<tr>
			<td>Protein Gene Product 9.5 (Polyclonal rabbit)</td>
			<td>AbD Serotec</td>
			<td>7863-0504</td>
			<td>PGP</td>
		</tr>
		<tr>
			<td>Tropomyosin Related-Kinase A (Polyclonal goat)</td>
			<td>R&amp;D Systems</td>
			<td>AF1056</td>
			<td>Trk A</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488 donkey &alpha;-rabbit</td>
			<td>Invitrogen</td>
			<td>A21206</td>
			<td>AF488 donkey &alpha;-goat</td>
		</tr>
		<tr>
			<td>Alexa Fluor 647 donkey &alpha;-goat</td>
			<td>Invitrogen</td>
			<td>A21447</td>
			<td>AF647 donkey &alpha;-goat</td>
		</tr>
		<tr>
			<td>Albumin, from Bovine Serum</td>
			<td>Sigma-Aldrich</td>
			<td>A7906-100</td>
			<td>BSA</td>
		</tr>
		<tr>
			<td>Triton X- 100</td>
			<td>Sigma-Aldrich</td>
			<td>T9284</td>
			<td>TX-100</td>
		</tr>
		<tr>
			<td>Non-calibrated Loop</td>
			<td>LeLoop</td>
			<td>MP 199025</td>
			<td>inoculating Loop</td>
		</tr>
		<tr>
			<td>96-well assay plate</td>
			<td>Corning Incorporated</td>
			<td>3603</td>
			<td>Well plate</td>
		</tr>
		<tr>
			<td>Prolong Gold antifade reagent with DAPI</td>
			<td>Invitrogen</td>
			<td>P36931</td>
			<td>DAPI</td>
		</tr>
		<tr>
			<td>Microscope Cover Glass 22x22 mm</td>
			<td>Fisher Scientific</td>
			<td>12-541-B</td>
			<td>Coverslips</td>
		</tr>
		<tr>
			<td>Superfrost Plus Microscope Slides</td>
			<td>Fisher Scientific</td>
			<td>12-550-15</td>
			<td>Microscope Slides</td>
		</tr>
		<tr>
			<td>Olympus Fluoview Laser Scanning Confocal Microscope</td>
			<td>Olympus</td>
			<td>FV500</td>
			<td>Confocal Microscope</td>
		</tr>
		<tr>
			<td>Optimum Cutting Temperature</td>
			<td>Sakura</td>
			<td>4583</td>
			<td>OCT</td>
		</tr>
		<tr>
			<td>Leica cryostat</td>
			<td>Leica</td>
			<td>CM1850</td>
			<td>Cryostat</td>
		</tr>
	</tbody>
</table>

three-dimensional imaging of nociceptive intraepidermal nerve fibers in human skin biopsies

A punch biopsy of the skin is commonly used to quantify intraepidermal nerve fiber densities (IENFD) for the diagnosis of peripheral polyneuropathy 1,2. At present, it is common practice to collect 3 mm skin biopsies from the distal leg (DL) and the proximal thigh (PT) for the evaluation of length-dependent polyneuropathies 3. However, due to the multidirectional nature of IENFs, it is challenging to examine overlapping nerve structures through the analysis of two-dimensional (2D) imaging. Alternatively, three-dimensional (3D) imaging could provide a better solution for this dilemma.
In the current report, we present methods for applying 3D imaging to study painful neuropathy (PN). In order to identify IENFs, skin samples are processed for immunofluorescent analysis of protein gene product 9.5 (PGP), a pan neuronal marker. At present, it is standard practice to diagnose small fiber neuropathies using IENFD determined by PGP immunohistochemistry using brightfield microscopy 4. In the current study, we applied double immunofluorescent analysis to identify total IENFD, using PGP, and nociceptive IENF, through the use of antibodies that recognize tropomyosin-receptor-kinase A (Trk A), the high affinity receptor for nerve growth factor 5. The advantages of co-staining IENF with PGP and Trk A antibodies benefits the study of PN by clearly staining PGP-positive, nociceptive fibers. These fluorescent signals can be quantified to determine nociceptive IENFD and morphological changes of IENF associated with PN. The fluorescent images are acquired by confocal microscopy and processed for 3D analysis. 3D-imaging provides rotational abilities to further analyze morphological changes associated with PN. Taken together, fluorescent co-staining, confocal imaging, and 3D analysis clearly benefit the study of PN.

We applied the current protocol to study the morphology of IENF in PT and DL skin biopsies from patients with PN. The skin, from three subjects, was collected at the University of Utah to demonstrate the pathomorphology associated with PN. The subjects include: Case 1: a 51-year-old male with a history of PN of type 2 diabetes (duration: 14 months; pain score: 51); Case 2: a 56-year-old male with a history of PN of type 2 diabetes (duration: 108 months; pain score: 47); and Case 3: a 66-year-old male with a history of PN...

Watch this Scientific Journal Video about Three-dimensional Imaging of Nociceptive Intraepidermal Nerve Fibers in Human Skin Biopsies at JoVE.com

Three-dimensional Imaging of Nociceptive Intraepidermal Nerve Fibers in Human Skin Biopsies

In order to study the changes of nociceptive intraepidermal nerve fibers (IENFs) in painful neuropathies (PN), we developed protocols that could directly examine three-dimensional morphological changes observed in nociceptive IENFs. Three-dimensional analysis of IENFs has the potential to evaluate the morphological changes of IENF in PN.

A punch biopsy of the skin is commonly used to quantify intraepidermal nerve fiber densities (IENFD) for the diagnosis of peripheral polyneuropathy 1,2. ...

three-dimensional-imaging-nociceptive-intraepidermal-nerve-fibers

Research

JoVE Journal

Medicine

13.0K Görüntüleme.  University of Michigan. Ağrılı nöropatiler (PN) olarak nosiseptif intraepidermal sinir lifleri (IENFs) değişiklikleri incelemek için, doğrudan nosiseptif IENFs gözlenen üç boyutlu morfolojik değişiklikleri incelemek olabilir protokolleri geliştirmiştir. IENFs üç boyutlu analiz PN İESL morfolojik değişiklikleri değerlendirmek için bir potansiyele sahiptir.