Initial upregulation of growth factors and inflammatory mediators during nerve regeneration in the presence of cell adhesive peptide‐incorporated collagen tubes

Abstract

Neurotrophic factors play an important modulatory role in axonal sprouting during nerve regeneration involving the proliferation of hematogenous and Schwann cells in damaged tissue. We have exposed lesioned sciatic nerves to a collagen prosthesis with covalently bonded small cell adhesive peptides Arg-Gly-Asp-Ser (RGDS), Lys-Arg-Asp-Ser (KRDS), and Gly-His-Lys (GHK) to study local production of growth factors and cytokines in the regenerating tissues. Western/enzyme-linked immunosorbent assay (ELISA) studies were performed after 10 days of regeneration, when the tubular prosthesis is filled with fibrous matrix infiltrated by hematogenous cells and proliferating Schwann cells with growth factors produced locally. Regeneration was also analyzed by morphometrical methods after 30 days. The quantification of growth factors and proteins by ELISA revealed that there was an enhanced expression of the neurotrophic factors nerve growth factor (NGF) and neurotrophins (NT-3 and NT-4) in the regenerating tissues. This was further established by Western blot to qualitatively analyze the presence of the antigens in the regenerating tissues. Schwann cells were localized in the regenerating tissues using antibodies against S-100 protein. Other growth factors including growth-associated protein 43 (GAP-43), apolipoprotein E (Apo E), and pro-inflammatory cytokine like interleukin-1alpha (IL-1alpha) expression in the peptide groups were evaluated by ELISA and confirmed by Western blotting. Cell adhesive integrins in the proliferating cells were localized using integrin-alpha V. The combined results suggest that the early phase of regeneration of peripheral nerves in the presence of peptide-incorporated collagen tubes results in the enhanced production of trophic factors by the recruited hematogenous cells and Schwann cells, which in turn help in the secretion of certain vital trophic and tropic factors essential for early regeneration. Furthermore, hematogenous cells recruited within the first 10 days of regeneration help in the production of inflammatory mediators like interleukins that in turn stimulate Schwann cells to produce NGF for axonal growth.

Scaffolds for Peripheral Nerve Regeneration, the Importance of In Vitro and In Vivo Studies for the Development of Cell-Based Therapies and Biomaterials: State of the Art

“…With that intend, new peptides have been engineered to mimic the active binding domains of various extracellular matrix molecules [177,178]. Coating with arginylglycylaspartic acid (RGD) sequences (the tripeptide Arg-Gly-Asp) also obtained very good results [117,[179][180][181][182]. Structure pore design is a great strategy to promote nerve regeneration.…”

Post-injury regeneration in rat sciatic nerve facilitated by neurotrophic factors secreted by amniotic fluid mesenchymal stem cells

“…26 Peripheral nerve regeneration involves Schwann cells, neurotrophic factors, and inflammatory cells working synergistically to promote and maintain axon sprouting and myelination of axons. 9,27,28 The supplementation of neurotrophic factors or cell therapy with cultured Schwann cells, ensheathing olfactory cells, neuronal stem cells or induced Schwann cells has been fully investigated. It seemed for a time that these strategies had great potential for clinical application.…”

The Human Tripeptide GHK-Cu in Prevention of Oxidative Stress and Degenerative Conditions of Aging: Implications for Cognitive Health

“…Ahmed et al established that nerve stubs placed in a collagen tube impregnated with GHK (used without copper) had an increased production of nerve growth factor and the neurotrophins NT-3 and NT-4 increased migration of cells into collagen tube and sped up the regeneration of nerve fibers. In addition, GHK also increased axon count and proliferation of the Schwann cells compared to the control group [50]. …”