Simple fabrication method for a porous poly(vinyl alcohol) matrix by multisolvent mixtures for an air-exposed model of the lung epithelial system.

We introduce a simple and easy method for fabricating a thin and porous matrix that can be used as an extracellular matrix (ECM). A porous poly(vinyl alcohol) (PVA) matrix was created through recrystallization by multiple solvents under distilled water (DW), isopropyl alcohol (IPA), and a combination of DW and IPA. The crysatllization was driven by precipitating and dissolving a solute in a solution of a solvent and a nonsolvent, which induced the formation of microspheres in the IPA. The crystal structure depended on the ratio of the solvent/nonsolvent and the concentration of the PVA aqueous solution; these properties were used to tune the thickness, size, and porosity of the matrices. The resulting PVA matrix was chemically stabilized through a reaction with glutaraldehyde in the IPA solution. We demonstrated that a very thin and porous PVA matrix provided an effective functional model of the lung epithelial system. Lung epithelial cells (A549) displayed a high affinity for this matrix, which was permeable to the culture medium. These properties facilitated culturing under the air environment.

Oil droplet generation in PDMS microchannel using an amphiphilic continuous phase.

This paper reports an amphiphilic solution can be used as a new continuous phase to generate double droplet emulsions (water/oil/IPA) with neither surface treatment nor surfactant in PDMS microfluidic chip. The affinity of various amphiphilic solutions in the microchannel was influenced by the polarity ratio and the size of molecules. The polarity ratio of isopropyl alcohol (IPA) was closest to that of the recovered PDMS surface and the chain length of IPA was also suitable for high affinity. IPA showed the highest affinity for the recovered PDMS and was selected as the continuous phase to form oil droplets in a PDMS microchannel. With this new continuous phase solution, IPA, we could successfully generate not only oil droplets but also double emulsions in the PDMS microfluidic chips.

Microfluidic spinning of flat alginate fibers with grooves for cell-aligning scaffolds.

Alginate microribbons with longitudinally grooved microstructures are continuously fabricated by means of a microfluidic system. The number and dimensions of the microgroovesare successfully controlled by regulation of the slit-shaped channel (yellow in figure). This method opens up the possibility of mass production of scaffolds for tissue engineering purposes, as it is proved that the grooved flat fibers can be used to align other types of cells in culture.

Using the chorions of fertilized zebrafish eggs as a biomaterial for the attachment and differentiation of mouse stem cells.

The development of proper biomaterials is critical for the success of cell therapy and modern tissue engineering. Here, we extruded the yolk and remaining inner mass from fertilized zebrafish eggs and used the resulting chorions as a biomaterial for the differentiation and attachment of mouse P19 embryonic carcinoma (EC) cells. Cells inserted into the chorion showed the spontaneous formation of embryoid body due to the repulsive cell adhesion of the chorion and differentiated specifically into neural cells and cardiomyocytes. In contrast, dissolved chorion extracellular matrix (ECM) conferred enhanced cell attachment on it, suggesting that a unique property of the zebrafish chorion with nanoporous structure appears to be responsible for the simple and controllable embryoid formation for stem cell differentiation. These results indicate that chorions from fertilized zebrafish eggs may be used as an extracellular matrix alternative and applied for stem cell differentiation to specific cell lineages.