Wenfang Li

Three-dimensional dynamic fabrication of engineered cartilage based on chitosan/gelatin hybrid hydrogel scaffold in a spinner flask with a special designed steel frame

Cartilage transplantation using in vitro tissue engineered cartilage is considered a promising treatment for articular cartilage defects. In this study, we assessed the advantages of adipose derived stem cells (ADSCs) combined with chitosan/gelatin hybrid hydrogel scaffolds, which acted as a cartilage biomimetic scaffold, to fabricate a tissue engineered cartilage dynamically in vitro and compared this with traditional static culture. Physical properties of the hydrogel scaffolds were evaluated and ADSCs were inoculated into the hydrogel at a density of 1×10(7) cells/mL and cultured in a spinner flask with a special designed steel framework and feed with chondrogenic inductive media for two weeks. The results showed that the average pore size, porosity, swelling rate and elasticity modulus of hybrid scaffolds with good biocompatibility were 118.25±19.51 μm, 82.60±2.34%, 361.28±0.47% and 61.2±0.16 kPa, respectively. ADSCs grew well in chitosan/gelatin hybrid scaffold and successfully differentiated into chondrocytes, showing that the scaffolds were suitable for tissue engineering applications in cartilage regeneration. Induced cells cultivated in a dynamic spinner flask with a special designed steel frame expressed more proteoglycans and the cell distribution was much more uniform with the scaffold being filled mostly with extracellular matrix produced by cells. A spinner flask with framework promoted proliferation and chondrogenic differentiation of ADSCs within chitosan/gelatin hybrid scaffolds and accelerated dynamic fabrication of cell-hydrogel constructs, which could be a selective and good method to construct tissue engineered cartilage in vitro.

Chitosan/gelatin porous scaffolds assembled with conductive poly(3,4-ethylenedioxythiophene) nanoparticles for neural tissue engineering

Electroactive biomaterials are widely explored as scaffolds for nerve tissue regeneration. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a conductive polymer that has been chosen to construct tissue engineered scaffolds because of its excellent conductivity and non-cytotoxicity. In the present study, an electrically conductive scaffold was prepared by assembling PEDOT on a chitosan/gelatin (Cs/Gel) porous scaffold surface via in situ interfacial polymerization. The hydrophilic Cs/Gel hydrogel was used as a template, and PEDOT nanoparticles were uniformly assembled on the scaffold surface. The static polymerization of the 3,4-ethylenedioxythiophene (EDOT) monomer at the interface between the aqueous phase and the organic phase was accompanied by the formation of the PEDOT-assembled Cs/Gel scaffolds. PEDOT/Cs/Gel scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The results confirmed the deposition of PEDOT nanoparticles with the mean diameter of 50 nm on the Cs/Gel scaffold channel surface. Compared to the Cs/Gel scaffold, the incorporation of PEDOT on the scaffold increased the electrical conductivity, hydrophilicity, mechanical properties and thermal stability, whereas decreased the water absorption and biodegradation. For biocompatibility, PEDOT/Cs/Gel scaffolds, especially the 2PEDOT/Cs/Gel scaffold group, significantly promoted neuron-like rat pheochromocytoma (PC12) cell adhesion and proliferation. The results of both the gene expression and protein level assessments suggested that the PEDOT-assembled Cs/Gel scaffold enhanced the PC12 cellular neurite growth with higher protein and gene expression levels. This is the first report on the construction of a conductive PEDOT/Cs/Gel porous scaffold via an in situ interfacial polymerization method, and the results demonstrate that it may be a promising conductive scaffold for neural tissue engineering.

Development and fabrication of a two-layer tissue engineered osteochondral composite using hybrid hydrogel-cancellous bone scaffolds in a spinner flask.

Biological treatment using engineered osteochondral composites has received growing attention for the repair of cartilage defects. Osteochondral composites combined with a dynamic culture provide great potential for improving the quality of constructs and cartilage regeneration as dynamic conditions mimic the in vivo condition where cells were constantly subjected to mechanical and chemical stimulation. In the present study, biophasic composites were produced in vitro consisting of cell-hydrogel (CH) and cell-cancellous bone (CB) constructs, followed by culturing in a dynamic system in a spinner flask. The aim of this study was to investigate cell behaviors (i.e. cell growth, differentiation, distribution and matrix deposition) cultured in different constructs under static and dynamic circumstances. As a result, we found that mechanical stimulation promoted osteogenic and chondrogenic differentiation of cells as indicated by the increased expression of ALP and glycosaminoglycan (GAG) in either bone or cartilage substitute materials. Dynamic culture yielded a preferable extracellular matrix production, particularly in hydrogel scaffolds. In addition, the enhanced mass transfer contributed to the interface formation, cells infiltration and distribution in the osteochondral composites. This study demonstrates that osteochondral composites incorporated with a dynamic culture improved the performance of the constructs, providing the basis for a promising tool and a better strategy for the rapid fabrication of osteochondral substitutes and regeneration of injured cartilage.

3D culture of neural stem cells within conductive PEDOT layer-assembled chitosan/gelatin scaffolds for neural tissue engineering

Neural stem cells (NSCs), as a self-renewing and multipotent cell population, have been widely studied for never regeneration. Engineering scaffold is one of the important factors to regulate NSCs proliferation and differentiation towards the formation of the desired cells and tissues. Because neural cells are electro-active ones, a conductive scaffold is required to provide three-dimensional cell growth microenvironments and appropriate synergistic cell guidance cues. In this study, a poly (3,4‑ethylenedioxythiophene)/chitosan/gelatin (PEDOT/Cs/Gel) scaffold was prepared via in situ interfacial polymerization, with a nanostructured layer of PEDOT assembling on the channel surface of porous Cs/Gel scaffold. This electrically conductive, three-dimensional, porous and biodegradable PEDOT/Cs/Gel scaffold was used as a novel scaffold for NSCs three-dimension (3D) culture in vitro. It was found that the layer of PEDOT on the channel surface of Cs/Gel scaffolds could greatly promote NSCs adhesion and proliferation. Additionally, under the differentiation condition, the protein and gene analysis suggested that PEDOT/Cs/Gel scaffolds could significantly enhance the NSCs differentiation towards neurons and astrocytes with the up-regulation of β tubulin-III and GFAP expression. In conclusion, these results demonstrated that the PEDOT/Cs/Gel scaffolds as an electrically conductive scaffold could not only promote NSCs adhesion and proliferation but also enhance NSCs differentiation into neurons and astrocytes with higher protein and gene expression. PEDOT-assembled Cs/Gel scaffold will be a promising conductive substrate for NSCs research and neural tissue engineering.