Morphology, Migration, and Transcriptome Analysis of Schwann Cell Culture on Butterfly Wings with Different Surface Architectures.

It has been shown that material surface topography greatly affects cell attachment, growth, proliferation, and differentiation. However, the underlying molecular mechanisms for cell-material interactions are still not understood well. Here, two kinds of butterfly wings with different surface architectures were employed for addressing such an issue. Papilio ulysses telegonus (P.u.t.) butterfly wing surface is composed of micro/nanoconcaves, whereas Morpho menelaus (M.m.) butterfly wings are decorated with grooves. RSC96 cells grown on M.m. wings showed a regular sorting pattern along with the grooves. On the contrary, the cells seeded on P.u.t. wings exhibited random arrangement. Transcriptome sequencing and bioinformatics analysis revealed that huntingtin (Htt)-regulated lysosome activity is a potential key factor for determining cell growth behavior on M.m. butterfly wings. Gene silence further confirmed this notion. In vivo experiments showed that the silicone tubes fabricated with M.m. wings markedly facilitate rat sciatic nerve regeneration after injury. Lysosome activity and Htt expression were greatly increased in the M.m. wing-fabricated graft-bridged nerves. Collectively, our data provide a theoretical basis for employing butterfly wings to construct biomimetic nerve grafts and establish Htt lysosome as a crucial regulator for cell-material interactions.

Electrospun silk fibroin-based neural scaffold for bridging a long sciatic nerve gap in dogs.

Silk fibroin (SF)-derived silkworms represent a type of highly biocompatible biomaterial for tissue engineering. We have previously investigated biocompatibility of SF with neural cells isolated from the central nervous system or peripheral nerve system in vitro, and also developed a SF-based nerve graft conduit or tissue-engineered nerve grafts by introducing bone marrow mesenchymal stem cells, as support cells, into SF-based scaffold and evaluated the outcomes of peripheral nerve repair in a rat model. As an extension of the previous study, the electrospun technique was performed here to fabricate SF-based neural scaffold inserted with silk fibres for bridging a 30-mm-long sciatic nerve gap in dogs. Assessments including functional, histological and morphometrical analyses were applied 12 months after surgery. All the results indicated that the SF-based neural scaffold group achieved satisfactory regenerative outcomes, which were close to those achieved by autologous nerve grafts as the golden-standard for peripheral nerve repair. Overall, our results raise a potential possibility for the translation of SF-based electrospun neural scaffolds as an alternative to nerve autografts into the clinic.

Bone marrow mesenchymal stem cell-derived acellular matrix-coated chitosan/silk scaffolds for neural tissue regeneration.

Extracellular/acellular matrix-containing neural scaffolds represent a promising design of a tissue engineered nerve graft (TENG) for peripheral nerve repair. In this study, we engineered a composite neural scaffold by culturing dog bone marrow mesenchymal stem cells (BMSCs) onto the surface of a chitosan/silk fibroin-based scaffold and then exposing the cell culture to decellularization to deposit acellular matrix (ACM) coatings on the scaffold. This natural biomaterial-based, cell-derived ACM-coated neural scaffold, as a novel nerve graft, was used to bridge a 60 mm long nerve gap in a dog sciatic nerve. At 12 months after grafting, behavioral, functional, and histological evaluation indicated that our developed neural scaffold achieved satisfactory regenerative outcomes, which were very close to those achieved by autologous nerve grafts, the accepted golden standard for peripheral nerve repair. Moreover, additional therapeutic benefits produced by the modification of a neural scaffold with BMSC-derived ACM may be associated with the unique neural activity of the ACM, as evidenced by in vitro experimental findings that the ACM significantly enhanced axonal regrowth and Schwann cell proliferation. Our results will provide a further experimental basis for the translation of ACM-containing neural scaffolds into the clinic.

Repair of Rat Sciatic Nerve Defects by Using Allogeneic Bone Marrow Mononuclear Cells Combined With Chitosan/Silk Fibroin Scaffold.

The therapeutic benefits of bone marrow mononuclear cells (BM-MNCs) in many diseases have been well established. To advance BM-MNC-based cell therapy into the clinic for peripheral nerve repair, in this study we developed a new design of tissue-engineered nerve grafts (TENGs), which consist of a chitosan/fibroin-based nerve scaffold and BM-MNCs serving as support cells. These TENGs were used for interpositional nerve grafting to bridge a 10-mm-long sciatic nerve defect in rats. Histological and functional assessments after nerve grafting showed that regenerative outcomes achieved by our developed TENGs were better than those achieved by chitosan/silk fibroin scaffolds and were close to those achieved by autologous nerve grafts. In addition, we used green fluorescent protein-labeled BM-MNCs to track the cell location within the chitosan/fibroin-based nerve scaffold and trace the cell fate at an early stage of sciatic nerve regeneration. The result suggested that BM-MNCs could survive at least 2 weeks after nerve grafting, thus helping to gain a preliminary mechanistic insight into the favorable effects of BM-MNCs on axonal regrowth.