When the temperature responsive polymer (PIPAAm) is fixed to the cell culturing plastic plate utilizing Bionano interface technology, the surface of the plate changes reversible hydrophilic-hydrophobic in response to temperature change across LCST of 32°C. The surface becomes hydrophobic over 32°C which enables cells to attach surface and grow.

However, when the temperature is reduced as low as 20°C, the polymer surface becomes hydrophilic and the hydrated polymer chains cause cultured cells to detach easily. Cells detach because the hydrophobic surface they were attaching to disappears under the LCST of 32°C.

Cell detachment

The key feature and advantages of using cell culturing plates/dishes coated with temperature responsive polymer (UpCell® and RepCell®) can be summarized as follows.

•Key features
Cultured cells can be collected by mere reduction of temperature.
Traditional methods of such detachment involving enzymatic means such as using trypsin or the like is no longer required when this dishes/plates are used for cell culture. It is a well known fact that using trypsin severly damages cells. (Click here to see how damaging the trypsin is.)

•Advantages
No suture required at all
Cells retaining the function of fibronectin are collected since detaching cells by temperature change does not damage cells. This leads to the advantage that no suture is required when the cultured cells/tissues are transplanted to the patients.

Cultured cells can be collected as a "sheet"
Since cell damaging enzyme is not required, cells can detach maintaining the cell-cell junction. This enables the collection of cultured cells as a single "sheet". Cell-sheet is highly effective when transplanted to patients due to tight communication between cells and cells. Our currently undergoing regenerative cornea project whose stage is at the clinical studies in a small scale proves this fact.

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Regenerative cornea cell sheet cultured by UpCell is detaching as a sheet.

The only technology that allows the construction of organs
The cultured cell sheet can be easily moved and piled up to the other cultured cell sheet to implement 3 dimensional cell culture. Since fibronectin is functioning, multiple layered cell sheet is easily constructed by just laying one cell sheet to the other. The technology is ultimately applicable to the construction of organs by laying different types of cell sheets.

Three dimensional cell culture was carried out with rat's cardiac cells. Active and completely unified, both in terms of structure and function, cardiac multiple layered cell sheet was constructed. The mulptile layered cardiac cell sheet was transplanted to nude mouse, and we have observed the vascularization around the patch and the blood vessels pulled into the cell sheet. The significant improvement of the function of the heart was also observed for a long period of time.

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Beating cardiac patch. Cardiac cell sheet was cultured on UpCell and 4 sheets were piled up.

This technology is referred to as "Cell-sheet engineering".