Application of Human Epineural Sheath Conduits Supported with Human Mesenchymal Stem Cells as a Novel Therapy for Enhancement of Nerve Gap Regeneration
Marcin Strojny, MD, University of Illinois at Chicago, Chicago, IL and Maria Siemionow, MD, PhD, DSc, Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL
INTRODUCTION: This study aimed to assess effect of human Epineural Sheath Conduit (hESC) supported with Human Mesenchymal Stem Cells (hMSC) on restoration of 20mm long nerve defect in a nude rat model.
MATERIALS AND METHODS: Restoration of 20mm sciatic nerve defect with hESC created from human sciatic nerve supported with hMSC was tested in 4 experimental groups: Group 1: no repair control (n=6), Group 2: autograft control (n=6), Group 3: hESC (n=6), Group 4: hESC+hMSC (n=6). Functional tests of toespread and pinprick were performed at 1, 3, 6, 9, 12 weeks after repair. At 12 weeks, immunofluorescence staining assessed presence of neurogenic, angiogenic and immunogenic markers. Toluidine blue staining and histomorphometric analysis assessed myelin thickness, axonal density, fiber diameter, and percentage of the myelinated nerve fibers. Gastrocnemius Muscle Index (GMI) and muscle fiber area ratio assessed muscle atrophy.
RESULTS: Macroscopic evaluation of epineural conduit repair site at 12 weeks confirmed preservation of a normal nerve shape without scar tissue, adhesions or local signs of inflammation and good vascularization in all groups. The best sensory and motor recovery was observed in Group 2, followed by Group 4, Group 3 and Group 1 (pinprick 3.0 vs. 2.33 vs. 2.0 vs. 0.5; toespread 1.83 vs. 1.5 vs. 1.0 vs. 0.13, respectively). GMI and muscle fiber area ratio was highest for Group 2 (0.322/0.414), followed by Group 4 (0.285/0.306), Group 3 (0.274/0.286) and Group 1 (0.167/0.098). The highest expression of VEGF, NGF and laminin B was found in Group 2, followed by Group 4, Group 3 and Group 1.
Group 4 confirmed HLADR expression. Myelin thickness reveled best values in Group 4 (0.65 ± 0.06 μm) followed by Group 2 (0.63 ± 0.10 μm) and Group 3 (0.47 ± 0.07 μm). Fiber diameter and percentage of myelinated nerve fibers significantly increased in Group 4 be (4.04. ± 0.31 μm /92 ± 3%) followed by Group 2 (3.79 ± 0.69 μm /83 ± 2 %) and Group 3 (3.35 ± 0.19 μm /74 ± 7%). Group 2 confirmed highest axonal density (322 ± 122), followed by Group 4 (167 ± 47) and Group 3 (133 ± 81).
CONCLUSIONS: We established feasibility of human ESC creation. Human ESC conduit efficacy in nerve regeneration at 12 weeks after nerve gap repair was comparable with autograft repair as confirmed by electron microscopy, immunofluorescence assays and functional tests. Our novel Human ESC introduces alternative technique to autograft nerve repair.
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