Effect of cryopreservation on the integrity of coaxial alginate capsules

Encapsulation of clinically relevant cells, such as multipotent stromal cells (MSCs), in three-dimensional (3D) core-shell alginate structures is a promising method for the treatment of various diseases as well as drug testing and development. By utilizing the alginate capsules, drugs and active substances can be delivered specifically to the desired place within the patients’ body. The aim of this work was to investigate the effect of cryopreservation on the integrity of cell-free coaxial alginate capsules after thawing using slow freezing to ensure their long-term storage. Alginate capsules were produced by electro-spraying and cryopreserved using different cryoprotective agents (CPAs), incubation time and thawing temperature. The results suggest that the capsules loaded with 10% (v/v) dimethyl sulfoxide (DMSO) and 0.3 M sucrose and using high thawing rates demonstrated a beneficial effect on the integrity of capsules, as compared to 10% (v/v) DMSO alone and applying low thawing rates. This study is a further development towards the application of cryopreservation for long-term storage and the emerging cell-based medicine.