Nerve conduits constructed by electrospun P(LLA-CL) nanofibers and PLLA nanofiber yarns.

Injuries of the peripheral nerve occur commonly in various people of different ages and backgrounds. Generally, surgical repairing, such as suturing the transected nerve stumps and transplanting an autologous nerve graft, is the only choice. However, tissue engineering provides an alternative strategy for regeneration of neural context. Functional nerve conduits with three dimensional (3D) support and guidance structure are badly in need. Herein, a uniform PLLA nanofiber yarn constructed by unidirectionally aligned nanofibers was fabricated via a dual spinneret system, which was subsequently incorporated into a hollow poly(l-lactide-co-caprolactone) (P(LLA-CL)) tube to form a nerve conduit with inner aligned texture. The biocompatibility of the poly(l-lactic acid) (PLLA) yarn was assessed by in vitro experiments. Schwann cells (SCs) presented a better proliferation rate and spread morphology of the PLLA yarn than that of PLLA film. Confocal images indicated that the axon spreads along the length of the yarn. SCs were also cultured in the conduit. The data indicated that SCs proliferated well in the conduit and distributed dispersedly throughout the entire lumen. These results demonstrated the potential of the PLLA nanofiber yarn conduit in nerve regeneration.

Dexamethasone loaded core-shell SF/PEO nanofibers via green electrospinning reduced endothelial cells inflammatory damage.

Silk fibroin (SF)/PEO nanofibers prepared by green electrospinning is safe, non-toxic and environment friendly, it is a potential drug delivery carrier for tissue engineering. In this study, a core-shell nanofibers named as Dex@SF/PEO were obtained by green electrospinning with SF/PEO as the shell and dexamethasone (Dex) in the core. The nanofiber morphology and core-shell structure were studied by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The Dex release behavior from the nanofibers was tested by High Performance liquid (HPLC) method. The protective effect of drug loaded nanofibers mats on Porcine hip artery endothelial cells (PIECs) against LPS-induced inflammatory damage were determined by MTT assay. TEM result showed the distinct core-shell structure of nanofibers. In vitro drug release studies demonstrated that dexamethasone can sustain release over 192 h and core-shell nanofibers showed more slow release of Dex compared with the blending electrospinning nanofibers. Anti-inflammatory activity in vitro showed that released Dex can reduce the PIECs inflammatory damage and apoptosis which induced by lipopolysaccharide (LPS). Dex@SF/PEO nanofibers are safe and non-toxic because of no harmful organic solvents used in the preparation, it is a promising environment friendly drug carrier for tissue engineering.

Three-dimensional polycaprolactone scaffold via needleless electrospinning promotes cell proliferation and infiltration.

Electrospinning has been widely used in fabrication of tissue engineering scaffolds. Currently, most of the electrospun nanofibers performed like a conventional two-dimensional (2D) membrane, which hindered their further applications. Moreover, the low production rate of the traditional needle-electrospinning (NE) also limited the commercialization. In this article, disc-electrospinning (DE) was utilized to fabricate a three-dimensional (3D) scaffold consisting of porous macro/nanoscale fibers. The morphology of the porous structure was investigated by scanning electron microscopy images, which showed irregular pores of nanoscale spreading on the surface of DE polycaprolactone (PCL) fibers. Protein adsorption assessment illustrated the porous structure could significantly enhance proteins pickup, which was 55% higher than that of solid fiber scaffolds. Fibroblasts were cultured on the scaffold. The results demonstrated that DE fiber scaffold could enhance initial cell attachment. In the 7 days of culture, fibroblasts grew faster on DE fiber scaffold in comparison with solid fiber, solvent cast (SC) film and TCP. Fibroblasts on DE fibers showed a stretched shape and integrated with the porous surface tightly. Cells were also found to migrate into the DE scaffold up to 800µm. Results supported the use of DE PCL fibers as a 3D tissue engineering scaffold in soft tissue regeneration.

Fabrication of cell penetration enhanced poly (l-lactic acid-co-ɛ-caprolactone)/silk vascular scaffolds utilizing air-impedance electrospinning.

In the vascular prosthetic field, the prevailing thought is that for clinical, long-term success, especially bioresorbable grafts, cellular migration and penetration into the prosthetic structure is required to promote neointima formation and vascular wall development. In this study, we fabricated poly (l-lactic acid-co-ɛ-caprolactone) P(LLA-CL)/silk fibroin (SF) vascular scaffolds through electrospinning using both perforated mandrel subjected to various intraluminal air pressures (0-300kPa), and solid mandrel. The scaffolds were evaluated the cellular infiltration in vitro and mechanical properties. Vascular scaffolds were seeded with smooth muscle cells (SMCs) to evaluate cellular infiltration at 1, 7, and 14 days. The results revealed that air-impedance scaffolds allowed significantly more cell infiltration as compared to the scaffolds fabricated with solid mandrel. Meanwhile, results showed that both mandrel model and applied air pressure determined the interfiber distance and the alignment of fibers in the enhanced porosity regions of the structure which influenced cell infiltration. Uniaxial tensile testing indicated that the air-impedance scaffolds have sufficient ultimate strength, suture retention strength, and burst pressure as well as compliance approximating a native artery. In conclusion, the air-impedance scaffolds improved cellular infiltration without compromising overall biomechanical properties. These results support the scaffold's potential for vascular grafting and in situ regeneration.