In-situ encapsulation of post-cryopreserved cells using alginate polymers and zwitterionic betaine

Currently, the state-of-the-art cryoprotectants for cell cryopreservation have bottleneck problems (such as cytotoxicity), which place enormous logistical limitations to the development of regenerative medicine. In this work, the first alginate polymer-based approach for human chondrocyte cryopreservation is reported. Combined with zwitterionic betaine, a natural osmoprotectant to offer intracellular protection, this alginate polymer-based approach can achieve ~90% cryopreservation efficiency. Owing to the biocompatibility of alginate polymers and betaine, this approach can easily retrieve the post-thaw cells without traditional multistep cryoprotectant washing procedures, which is highly favorable to cell therapy. Meanwhile, owing to the feasible and mild gelation process of alginate polymers, this approach can also directly encapsulate the post-thaw cells into hydrogels without cryoprotectant removal, which is highly useful to tissue engineering. Moreover, these hydrogels exhibit tunable mechanical prop...