An Antifreezing Scaffold-Based Cryopreservation Platform of Stem Cells for Convenient Application in Wound Repair.

Efficient cryopreservation of stem cells is crucial to fabricating off-the-shelf cell products for tissue engineering and regeneration medicine. However, it remains challenging due to utilization of toxic cryoprotectants for reducing ice-related cryodamages to stem cells during freeze-thaw cycle, stringent post-thaw washing process, and further integration of stem cells with scaffolds to form tissue engineering constructs for downstream applications. Herein, a novel cryopreservation platform of stem cells based on an antifreezing polyvinylpyrrolidone/gellan gum/gelatin (PGG) scaffold together is reported with an L-proline assisted cell pre-dehydration strategy. Results show that this platform is capable of inhibiting extra-/intracellular ice, thus can achieve high cryoprotection efficacy to stem cells (≈95%) without using any toxic cryoprotectants and eliminate traditional washing process. Meanwhile, the post-thawed stem cells can maintain their proliferation, differentiation, and paracrine functionalities. More importantly, due to the biocompatibility and three dimensional structure of the PGG scaffold, the post-thawed stem cell-laden PGG scaffold can be directly used as tissue engineering constructs for wound repair by mitigating inflammation and promoting collagen deposition at regenerating tissue sites. This present work demonstrates the feasibility of antifreezing scaffold-based cryopreservation platform of stem cells, which may advance the off-the-shelf stem cell-laden tissue engineering constructs for clinical translation.