Toyoshige Kobayashi

Corneal regeneration by transplantation of corneal epithelial cell sheets fabricated with automated cell culture system in rabbit model

We have performed clinical applications of cell sheet-based regenerative medicine with human patients in several fields. In order to achieve the mass production of transplantable cell sheets, we have developed automated cell culture systems. Here, we report an automated robotic system utilizing a cell culture vessel, cell cartridge. The cell cartridge had two rooms for epithelial cells and feeder layer cells separating by porous membrane on which a temperature-responsive polymer was covalently immobilized. After pouring cells into this robotic system, cell seeding, medium change, and microscopic examination during culture were automatically performed according to the computer program. Transplantable corneal epithelial cell sheets were successfully fabricated in cell cartridges with this robotic system. Then, fabricated cell sheets were transplanted onto ocular surfaces of rabbit limbal epithelial stem cell deficiency model after 6-h transportation using a portable homothermal container to keep inner temperature at 36 °C. Within one week after transplantation, normal corneal epithelium was successfully regenerated. This automatic cell culture system would be useful for industrialization of tissue-engineered products for regenerative medicine.

Fabrication of transplantable corneal epithelial and oral mucosal epithelial cell sheets using a novel temperature-responsive closed culture device

Temperature‐responsive culture surfaces make it possible to harvest transplantable carrier‐free cell sheets. Here, we applied temperature‐responsive polymer for polycarbonate surfaces with previously developed closed culture devices for an automated culture system in order to fabricate transplantable stratified epithelial cell sheets. Histological and immunohistochemical analyses and colony‐forming assays revealed that corneal epithelial and oral mucosal epithelial cell sheets could be harvested with the temperature‐responsive closed culture devices. The results were similar to those obtained using temperature‐responsive culture inserts. These results indicate that the novel temperature‐responsive closed culture device is useful for fabricating transplantable stratified epithelial cell sheets. Copyright

A novel closed cell culture device for fabrication of corneal epithelial cell sheets

Automation technology for cell sheet‐based tissue engineering would need to optimize the cell sheet fabrication process, stabilize cell sheet quality and reduce biological contamination risks. Biological contamination must be avoided in clinical settings. A closed culture system provides a solution for this. In the present study, we developed a closed culture device called a cell cartridge, to be used in a closed cell culture system for fabricating corneal epithelial cell sheets. Rabbit limbal epithelial cells were cultured on the surface of a porous membrane with 3T3 feeder cells, which are separate from the epithelial cells in the cell cartridges and in the cell‐culture inserts as a control. To fabricate the stratified cell sheets, five different thicknesses of the membranes which were welded to the cell cartridge, were examined. Multilayered corneal epithelial cell sheets were fabricated in cell cartridges that were welded to a 25 µm‐thick gas‐permeable membrane, which was similar to the results with the cell‐culture inserts. However, stratification of corneal epithelial cell sheets did not occur with cell cartridges that were welded to 100–300 µm‐thick gas‐permeable membranes. The fabricated cell sheets were evaluated by histological analyses to examine the expression of corneal epithelial‐specific markers. Immunohistochemical analyses showed that a putative stem cell marker, p63, a corneal epithelial differentiation maker, CK3, and a barrier function marker, Claudin‐1, were expressed in the appropriate position in the cell sheets. These results suggest that the cell cartridge is effective for fabricating corneal epithelial cell sheets. Copyright

A novel, flexible and automated manufacturing facility for cell-based health care products: Tissue Factory

Introduction Current production facilities for Cell-Based Health care Products (CBHPs), also referred as Advanced-Therapy Medicinal Products or Regenerative Medicine Products, are still dependent on manual work performed by skilled workers. A more robust, safer and efficient manufacturing system will be necessary to meet the expected expansion of this industrial field in the future. Thus, the ‘flexible Modular Platform (fMP)’ was newly designed to be a true “factory” utilizing the state-of-the-art technology to replace conventional “laboratory-like” manufacturing methods. Then, we built the Tissue Factory as the first actual entity of the fMP. Methods The Tissue Factory was designed based on the fMP in which several automated modules are combined to perform various culture processes. Each module has a biologically sealed chamber that can be decontaminated by hydrogen peroxide. The asepticity of the processing environment was tested according to a pharmaceutical sterility method. Then, three procedures, production of multi-layered skeletal myoblast sheets, expansion of human articular chondrocytes and passage culture of human induced pluripotent stem cells, were conducted by the system to confirm its ability to manufacture CHBPs. Results Falling or adhered microorganisms were not detected either just after decontamination or during the cell culture processes. In cell culture tests, multi-layered skeletal myoblast sheets were successfully manufactured using the method optimized for automatic processing. In addition, human articular chondrocytes and human induced-pluripotent stem cells could be propagated through three passages by the system at a yield comparable to manual operations. Conclusions The Tissue Factory, based on the fMP, successfully reproduced three tentative manufacturing processes of CBHPs without any microbial contamination. The platform will improve the manufacturability in terms of lower production cost, improved quality variance and reduced contamination risks. Moreover, its flexibility has the potential to adapt to the modern challenges in the business environment including employment issues, low operational rates, and relocation of facilities. The fMP is expected to become the standard design basis of future manufacturing facilities for CBHPs.