Mechanism of Peripheral Nerve Regeneration Using a Bio 3D Conduit Derived from Normal Human Dermal Fibroblasts

BACKGROUND: We previously reported the development of a scaffold-free Bio three-dimensional (3D) nerve conduit from normal human dermal fibroblasts (NHDFs). The aim of this study was to investigate the regenerative mechanism of peripheral nerve cells using a Bio 3D conduit in a rat sciatic nerve defect model. METHODS: Bio 3D conduits composed of NHDFs were developed, and cell viability was evaluated using a LIVE/DEAD cell viability assay immediately before transplantation and 1-week post-surgery. Tracking analysis using PKH26-labeled NHDFs was performed to assess the distribution of NHDFs within the regenerated nerve and the differentiation of NHDFs into functional Schwann cells (SCs). RESULTS: The assessment of the viability of cells within the Bio 3D conduit showed high cell viability both immediately before transplantation and 1-week post-surgery (88.56 ± 1.70 and 87.58 ± 9.11, respectively). A modified Masson's trichrome staining of the Bio 3D conduit revealed the formation of a prominent extracellular matrix (ECM) in between the cells. We observed, via tracking analysis, that the tube-like distribution of the NHDFs remained stable, the majority of the regenerated axons had penetrated this structure and PKH26-labeled cells were also positive for S-100. CONCLUSION: Abundant ECM formation resulted in a stable tube-like structure of the Bio 3D conduit with high cell viability. NHDFs in the Bio 3D conduit have the potential to differentiate into SCs-like cells.