Viable cryopreserving tissue-engineered cell-biomaterial for cell banking therapy in an effective cryoprotectant

The application of cell-biomaterial systems in tissue engineering and regenerative medicine is an important challenge in biomedicine, which preserves not only cells, but also tissue-engineered constructs. In this study, the constructs and cryoprotectant parameters were optimized, and it was evaluated whether the characteristics of dental pulp stem cells (DPSCs), which have high proliferation ability as stem cells, were maintained during encapsulation and cryopreservation. The optimal cell-biomaterial gel constructs with the gelation rate of 2% alginate: 100  mM CaCO(3): 200  mM glucono-δ-lactone (GDL)=4:1:1 and suitable cryoprotectants (CPAs) used for cryopreservation were Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% ethylene glycol (EG), 1.0  M sucrose and 0.00075  M polyvinylpyrrolidone (PVP). Optimality was confirmed by cell viability (trypan blue, live/dead analysis), the proliferation of DPSCs, and the microstructure using scanning electron microscopy (SEM) in the constructs, and surface epitope by flow cytometric analysis before and after cryopreservation. There were no visible differences in the structure. In conclusion, this study indicates that the optimal cell-biomaterial gel constructs and the cryoprotectant are promising biomaterials. The defined encapsulation/thawing system offers an excellent option for cell-banking therapy to be developed with ready-to-use viable biomaterials and patient-specific products as drug delivery systems.