BackgroundAlthough autologous nerve grafting is the gold standard treatment of peripheral nerve injuries, several alternative methods have been developed, including nerve conduits that use supportive cells. However, the seeding efficacy and viability of supportive cells injected in nerve grafts remain unclear. Here, we focused on a novel completely biological, tissue-engineered, scaffold-free conduit.MethodsWe developed six scaffold-free conduits from human normal dermal fibroblasts using a Bio 3D Printer. Twelve adult male rats with immune deficiency underwent mid-thigh-level transection of the right sciatic nerve. The resulting 5-mm nerve gap was bridged using 8-mm Bio 3D conduits (Bio 3D group, n = 6) and silicone tube (silicone group, n = 6). Several assessments were conducted to examine nerve regeneration eight weeks post-surgery.ResultsKinematic analysis revealed that the toe angle to the metatarsal bone at the final segment of the swing phase was significantly higher in the Bio 3D group than the silicone group (-35.78 ± 10.68 versus -62.48 ± 6.15, respectively; p < 0.01). Electrophysiological studies revealed significantly higher compound muscle action potential in the Bio 3D group than the silicone group (53.60 ± 26.36% versus 2.93 ± 1.84%; p < 0.01). Histological and morphological studies revealed neural cell expression in all regions of the regenerated nerves and the presence of many well-myelinated axons in the Bio 3D group. The wet muscle weight of the tibialis anterior muscle was significantly higher in the Bio 3D group than the silicone group (0.544 ± 0.063 versus 0.396 ± 0.031, respectively; p < 0.01).ConclusionsWe confirmed that scaffold-free Bio 3D conduits composed entirely of fibroblast cells promote nerve regeneration in a rat sciatic nerve model.

Cells, scaffolds, growth factors, and vascularity are essential for nerve regeneration. Previously, we reported that the insertion of a vascular bundle and the implantation of bone marrow-derived mesenchymal stem cells (BM-MSCs) into a nerve conduit promoted peripheral nerve regeneration. In this study, the efficacy of nerve conduits containing a vascular bundle, BM-MSCs, and thermally decellularized allogenic nerve matrix (DANM) was investigated using a rat sciatic nerve model with a 20-mm defect. Lewis rats were used as the sciatic nerve model and for the preparation of BM-MSCs, and Dark Agouti rats were used for the preparation of the DANM. The revascularization and the immunogenicity of the DANM were investigated histologically. The regeneration of nerves through nerve conduits containing vessels, BM-MSCs, and DANM (VBD group) was evaluated based on electrophysiological, morphometric, and reinnervated muscle weight measurements and compared with that of vessel-containing conduits that were implanted with BM-MSCs (VB group). The DANM that was implanted into vessel-containing tubes (VCTs) was revascularized by neovascular vessels that originated from the inserted vascular bundle 5-7 days after surgery. The number of CD8 + cells found in the DANM in the VCT was significantly smaller than that detected in the untreated allogenic nerve segment. The regenerated nerve in the VBD group was significantly superior to that in the VB group with regard to the amplitude of the compound muscle action potential detected in the pedal adductor muscle; the number, diameter, and myelin thickness of the myelinated axons; and the tibialis anterior muscle weight at 12 and 24 weeks. The additional implantation of the DANM into the BM-MSC-implanted VCT optimized the axonal regeneration through the conduit. Nerve conduits constructed with vascularity, cells, and scaffolds could be an effective strategy for the treatment of peripheral nerve injuries with significant segmental defects.

Introduction Superior capsule reconstruction (SCR) has been used for the tendon grafting of massive rotator cuff tears when primary repair is difficult. We examined the postoperative outcomes of SCR for massive rotator cuff tears and the risk factors for postoperative retear. Materials and methods Through this retrospective comparative study, we evaluated 35 patients with an average age of 75.3 (57-90) years who underwent SCR using the technique developed by Mihata et al. Clinical outcomes were evaluated 1 year postoperatively using the Japan Orthopedic Association (JOA) score, University of California Los Angeles (UCLA) shoulder score, elevation angle and the Sugaya classification, which uses a 5-point scale evaluation on magnetic resonance imaging in which types 4 and 5 are considered retears. We also investigated the progression of fatty degeneration before and after surgery and the rupture site of the graft. Acromio-humeral distance (AHD), before and after surgery was measured through X-rays. Rotator cuff tear-related shoulder arthritis was evaluated on plain X-rays using the Hamada stage. Risks of retear were identified using multiple regression analyses for sex, age, Hamada stage and JOA score. Results The JOA score improved from 62.3 ± 9.49 (SD) preoperatively to 84.6 ± 5.66 (SD) postoperatively (P < 0.001). The UCLA score improved from 15.3 ± 3.77 (SD) preoperatively to 30.1 ± 3.11 (SD) postoperatively (P < 0.001). AHD increased from 4.03 mm preoperatively to 6.23 mm postoperatively (P < 0.001). Postoperative retear was observed in seven of the 35 patients. Moreover, retear was observed in five of nine patients with a Hamada stage ≥ 4. Multiple regression analysis revealed that age ≥ 80 years, male sex and Hamada stage ≥ 4 were risk factors for retear. Conclusions While the postoperative outcomes of SCR are favorable, age, sex and degree of arthropathic change should be considered for surgical indications of SCR.

Previously, we showed that undifferentiated bone marrow stromal cell (uBMSC) implantation and vessel insertion into a nerve conduit facilitated peripheral nerve regeneration in a rodent model. In this study, we investigated the efficacy of the uBMSC-laden vessel-containing conduit in repair of segmental nerve defects, using a canine model. Eight beagle dogs were used in this study. Thirty-millimeter ulnar nerve defects were repaired with the conduits (right forelimbs, n = 8) or autografts (left forelimbs, n = 7). In the conduit group, the ulnar artery was inserted into the l-lactide/ε-caprolactone tube, which was filled with autologous uBMSCs obtained from the ilium. In the autograft group, the reversed nerve segments were sutured in situ. At 8 weeks, one dog with only nerve repair with the conduit was sacrificed and the regenerated nerve in the conduit underwent immunohistochemistry for investigation of the differentiation capability of the implanted uBMSCs. In the remaining seven dogs, the repaired nerves underwent electrophysiological examination at 12 and 24 weeks and morphometric measurements at 24 weeks. The wet weight of hypothenar muscles was measured at 24 weeks. At 8 weeks, almost 35% of the implanted uBMSCs expressed glial markers. At 12 weeks, amplitude (0.4 ± 0.4mV) and conduction velocity (18.9 ± 14.3m/s) were significantly lower in the conduit group than in the autograft group (3.2 ± 2.5 mV, 34.9 ± 12.1 m/s, P < 0.05). Although the nerve regeneration in the conduit group was inferior when compared with the autograft group at 24 weeks, there were no significant differences between both groups, regarding amplitude (10.9 ± 7.3 vs. 25.3 ± 20.1 mV; P = 0.11), conduction velocity (23.5 ± 8.7 vs 31.6 ± 20.0m/s; P = 0.35), myelinated axon number (7032 ± 4188 vs 7165 ± 1814; P = 0.94), diameter (1.73 ± 0.31 vs 2.09 ± 0.39μm; P = 0.09), or muscle weight (1.02 ± 0.40 vs 1.19 ± 0.26g; P = 0.36). In conclusion, this study showed that vessel-containing tubes with uBMSC implantation may be an option for treatment of peripheral nerve injuries. However, further investigations are needed. © 2015 Wiley Periodicals, Inc. Microsurgery 36:316-324, 2016.

Autologous nerve grafting is widely accepted as the gold standard treatment for segmental nerve defects. To overcome the inevitable disadvantages of the original method, alternative methods such as the tubulization technique have been developed. Several studies have investigated the characteristics of an ideal nerve conduit in terms of supportive cells, scaffolds, growth factors, and vascularity. Previously, we confirmed that biological scaffold-free conduits fabricated from human dermal fibroblasts promote nerve regeneration in a rat sciatic nerve injury model. The purpose of this study is to evaluate the feasibility of biological scaffold-free conduits composed of autologous dermal fibroblasts using a large-animal model. Six male beagle dogs were used in this study. Eight weeks before surgery, dermal fibroblasts were harvested from their groin skin and grown in culture. Bio 3D conduits were assembled from proliferating dermal fibroblasts using a Bio 3D printer. The ulnar nerve in each dog’s forelimb was exposed under general anesthesia and sharply cut to create a 5 mm interstump gap, which was bridged by the prepared 8 mm Bio 3D conduit. Ten weeks after surgery, nerve regeneration was investigated. Electrophysiological studies detected compound muscle action potentials (CMAPs) of the hypothenar muscles and motor nerve conduction velocity (MNCV) in all animals. Macroscopic observation showed regenerated ulnar nerves. Low-level hypothenar muscle atrophy was confirmed. Immunohistochemical, histological, and morphometric studies confirmed the existence of many myelinated axons through the Bio 3D conduit. No severe adverse event was reported. Hypothenar muscles were re-innervated by regenerated nerve fibers through the Bio 3D conduit. The scaffold-free Bio 3D conduit fabricated from autologous dermal fibroblasts is effective for nerve regeneration in a canine ulnar nerve injury model. This technology was feasible as a treatment for peripheral nerve injury and segmental nerve defects in a preclinical setting.