Application of Human Epineural Conduit Supported with Human Mesenchymal Stem Cells as a Novel Therapy for Enhancement of Nerve Gap Regeneration

Abstract

Various therapeutic methods have been suggested to enhance nerve regeneration. In this study, we propose a novel approach for enhancement of nerve gap regeneration by applying human epineural conduit (hEC) supported with human mesenchymal stem cells (hMSC), as an alternative to autograft repair. Restoration of 20 mm sciatic nerve defect with hEC created from human sciatic nerve supported with hMSC was tested in 4 experimental groups (n = 6 each) in the athymic nude rat model (Crl:NIH-Foxn1rnu): 1 - No repair control, 2 - Autograft control, 3 - Matched diameter hEC filled with 1 mL saline, 4 - Matched diameter hEC supported with 3 × 106 hMSC. Assessments included: functional tests: toe-spread and pinprick, regeneration assessment by immunofluorescence staining: HLA-1, HLA-DR, NGF, GFAP, Laminin B, S-100, VEGF, vWF and PKH26 labeling; histomorphometric analysis of myelin thickness, axonal density, fiber diameter and myelinated nerve fibers percentage; Gastrocnemius Muscle Index (GMI) and muscle fiber area ratio. Best sensory and motor function recovery, as well as GMI and muscle fiber area ratio, were observed in the autograft group, and were comparable to the hEC with hMSC group (p = 0.038). Significant improvements of myelin thickness (p = 0.003), fiber diameter (p = 0.0296), and percentage of myelinated fibers (p < 0.0001) were detected in hEC group supported with hMSC compared to hEC with saline controls. At 12-weeks after nerve gap repair, hEC combined with hMSC revealed increased expression of neurotrophic and proangiogenic factors, which corresponded with improvement of function comparable with the autograft control. Application of our novel hEC supported with hMSC provides a potential alternative to the autograft nerve repair. Graphical Abstract

Assessment of Human Epineural Conduit of Different Size Diameters on Efficacy of Nerve Regeneration and Functional Outcomes

“…Muscle denervation atrophy was assessed by calculating the gastrocnemius muscle index (GMI) and muscle fiber area ratio as described previously. 7 Briefly at the 12 weeks study endpoint, under euthanasia gastrocnemius muscles were harvested from both limbs, and wet-muscle weight was taken with digital scale (Ohaus Precision Standard, Germany) and the wet weight of the ipsilateral r and contralateral gastrocnemius was used to calculate the GMI. The GMI represented the percentage of the muscle denervation atrophy recovery on the operated side.…”

“…We have previously reported encouraging results when using epineural conduits (ECs) of the rat and sheep origin. [4][5][6][7] ECs have been gaining interest in recent years, due to unlimited accessibility, acellular properties, and neuroregenerative potential. Moreover, the neural origin of the EC represents a potential advantage over the other types of the biological tubes.…”

Benefit of Adjuvant Mesenchymal Stem Cell Transplantation to Critical-Sized Peripheral Nerve Defect Repair: A Systematic Review and Meta-Analysis of Preclinical Studies

“…Mesenchymal stem cells (MSCs) are cells with the ability to self-renewal and differentiate into adult cells. MSCs are thought to be a viable new treatment for extended nerve defects because of their advantageous effects on promoting axonal regeneration [ 5 , 6 ]. The positive influence of MSCs on peripheral nerve regeneration is hypothesized to be rooted in multiple aspects of their biological characteristics, such as factor secretion, immunomodulation, and their ability for potential further differentiation into Schwann-like cells [ 5 , 6 , 7 ].…”

“…MSCs are thought to be a viable new treatment for extended nerve defects because of their advantageous effects on promoting axonal regeneration [ 5 , 6 ]. The positive influence of MSCs on peripheral nerve regeneration is hypothesized to be rooted in multiple aspects of their biological characteristics, such as factor secretion, immunomodulation, and their ability for potential further differentiation into Schwann-like cells [ 5 , 6 , 7 ]. MSCs can secrete a broad repertoire of bioactive factors, including cytokines, growth factors, microRNAs, proteasomes, and exosomes, which can enhance angiogenesis, stimulate axonal regeneration, and prevent nerve tissue from excessive inflammation by depressing overaggressive activation of T-lymphocytes and natural killer cells [ 8 ].…”

Comparison of three different strategies to treat sciatic nerve regeneration: an experimental study

“…The use of stem cells aims to increase nerve regeneration through cellular differentiation and proliferation in nerve and glial cells. Additionally, the paracrine effect of adipose tissue stem cells (ASC) promotes anti-inflammatory action [9][10][11][12] .…”