Impaired neurovascular repair in subjects with diabetes following experimental intracutaneous axotomy

Gigi Ebenezer, Ryan O'Donnell, Peter Hauer, Nicholas P. Cimino, Justin Charles McArthur, Michael J Polydefkis

Research output: Contribution to journalArticle

Abstract

Diabetic complications and vascular disease are closely intertwined. Diabetes mellitus is a well-established risk factor for both large and small vessel vascular changes, and conversely other vascular risk factors confer increased risk for diabetic complications such as peripheral neuropathy, nephropathy and retinopathy. Furthermore, axons and blood vessels share molecular signals for purposes of navigation, regeneration and terminal arborizations. We examined blood vessel, Schwann cell and axonal regeneration using validated axotomy models to study and compare patterns and the relationship of regeneration among these different structures. Ten subjects with diabetes mellitus complicated by neuropathy and 10 healthy controls underwent 3 mm distal thigh punch skin biopsies to create an intracutaneous excision axotomy followed by a concentric 4-mm overlapping biopsy at different time points. Serial sections were immunostained against a pan-axonal marker (PGP9.5), an axonal regenerative marker (GAP43), Schwann cells (p75) and blood vessels (CD31) to visualize regenerating structures in the dermis and epidermis. The regenerative and collateral axonal sprouting rates, blood vessel growth rate and Schwann cell density were quantified using established stereology techniques. Subjects also underwent a chemical 'axotomy' through the topical application of capsaicin, and regenerative sprouting was assessed by the return of intraepidermal nerve fibre density through regenerative regrowth. In the healed 3 mm biopsy sites, collateral and dermal regenerative axonal sprouts grew into the central denervated area in a stereotypic pattern with collateral sprouts growing along the dermal-epidermal junction while regenerative dermal axons, blood vessels and Schwann cells grew from their transected proximal stumps into the deep dermis. Vessel growth preceded axon and Schwann cell migration into the denervated region, perhaps acting as scaffolding for axon and Schwann cell growth. In control subjects, Schwann cell growth was more robust and extended into the superficial dermis, while among subjects with diabetes mellitus, Schwann tubes appeared atrophic and were limited to the mid-dermis. Rates of collateral (P = 0.0001), dermal axonal regenerative sprouting (P = 0.02), Schwann cell migration (P <0.05) and blood vessel growth (P = 0.002) were slower among subjects with diabetes mellitus compared with control subjects. Regenerative deficits are a common theme in diabetes mellitus and may underlie the development of neuropathy. We observed that blood vessel growth recapitulated the pattern seen in ontogeny and preceded regenerating nerve fibres, suggesting that enhancement of blood vessel growth might facilitate axonal regeneration. These models are useful tools for the efficient investigation of neurotrophic and regenerative drugs, and also to explore factors that may differentially affect axonal regeneration.

Original languageEnglish (US)
Pages (from-to)1853-1863
Number of pages11
JournalBrain
Volume134
Issue number6
DOIs
StatePublished - Jun 2011

Fingerprint

Axotomy
Schwann Cells
Blood Vessels
Regeneration
Dermis
Diabetes Mellitus
Growth
Axons
Skin
Diabetes Complications
Biopsy
Nerve Fibers
Cell Movement
Diabetic Angiopathies
Capsaicin
Peripheral Nervous System Diseases
Thigh
Epidermis
Blood Cells
Cell Count

Keywords

  • blood vessels
  • diabetic neuropathy
  • peripheral nerve regeneration
  • Schwann cells
  • stereology

ASJC Scopus subject areas

  • Clinical Neurology

Cite this

Impaired neurovascular repair in subjects with diabetes following experimental intracutaneous axotomy. / Ebenezer, Gigi; O'Donnell, Ryan; Hauer, Peter; Cimino, Nicholas P.; McArthur, Justin Charles; Polydefkis, Michael J.

In: Brain, Vol. 134, No. 6, 06.2011, p. 1853-1863.

Research output: Contribution to journalArticle

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