Yuki Hikichi

Creation of cell micropatterns using a newly developed gel micromachining technique

Creation of cell micropatterns comprising heterogeneous cell populations is an important technique for tissue engineering, medical transplantation, drug discovery, and regenerative medicine. This paper presents a novel gel patterning technique similar to general micromachining for creating cell micropatterns using alginate gel to inhibit cell adhesion. The alginate thin-film micropattern was formed on a glass plate by photolithography and wet etching. Cell micropatterns were subsequently created along the alginate micropattern on the glass plate. This technique permits the creation of cell micropatterns with arbitrary geometry because hydrogel materials promoting or inhibiting cell adhesion can be patterned precisely. Moreover, this technique permits processing of the culture surface during cultivation because none of the materials used such as hydrogels and hydrogel-etching solutions exhibit cytotoxicity. A cell micropattern comprising different cell types was successfully created using the presented technique. This technique will be conducive to further improvement of the fabrication of artificial tissues formed by heterogeneous cells.

Measurement of cell mechanical properties by cell compression microdevice

This paper presents a measurement method for Youngs modulus of cells using fabricated microdevice. This presented method is based on two processes. A first step is cell compressive experiment using fabricated microdevice. The second step is a theoretical calculation for comparing with the experimental results. Cell compression microdevice was designed for controlling the magnitude of pressure to cells. The device consists of microchannels, cell culture chambers, and a diaphragm on the culture chamber for applying pressure to cells. The cells are directly compressed from the diaphragm above the cell culture chamber. The cell strain amount to the applied pressure was measured in the cell compressive experiment. Based on the experimental results, the Youngs modulus of cell was determined. The results obtained on Youngs modulus measurement of cells are comparatively similar to previously measured values by other researchers.

Fabrication of a microwell array having convertible cell culture surface and observation of cellular behavior

This paper presents a microwell array that can convert cell-non-adhesiveness of the culture surface to cell-adhesiveness. This microwell array is used to evaluate cellular differentiation behavior by converting cell culture surface. The alginate thin film is used as a material that inhibits adhesion of cells. First, the coating method of alginate gel was developed. It is formed on a cell culture surface by spin-coating of sodium alginate solution and dipping into calcium chloride (CaCl2) solution. Also, it can be removed by alginate lyase at arbitrary timing during cell culture. We demonstrated the effect of the thickness of the alginate thin film on cell adhesion. As a result, the alginate thin film completely inhibited the adhesion of myoblasts to the culture surface regardless of the thickness. Also, the experiment of myoblasts differentiation was carried out using fabricated microwell array. The myoblasts making up the spheroids spread out onto the culture surface and cells concurrently proceeded to fuse by adhering culture surface with many adjacent cells. The fused and spread myoblasts differentiated and formed myotube cells by 244h of culture. In addition, myoblasts cultured on the fabricated microwell array fused more effectively than cultured on the bare glass surface.