Cell encapsulation within PVA-based hydrogels via freeze-thawing: a one-step scaffold formation and cell storage technique

Cryogelation is a physical hydrogel formation method for certain polymers, notably polyvinyl alcohol (PVA). The hypothesis of this study is that a PVA-based solution with the necessary intracellular cryoprotectant and nutrient supply can be used, first for storage of vascular smooth muscle cells, and subsequently to form a suitable tissue-engineering scaffold during the thawing process. Bovine arterial smooth muscle cells were encapsulated within PVA-gelatin hydrogels over a wide range of serum, DMSO and cell culture medium concentrations. Several parameters expected to affect gelation and cell viability (PVA viscosity, DMSO concentration, serum presence) were assessed with experimental designs and the optimal conditions for cell survival were determined. Cell viability can be improved by increasing concentration of DMSO and serum without compromising the gelation process. An additional crosslinking step using a coagulation bath was beneficial for hydrogel stability but caused peripheral accumulation of cells. In conclusion, a freeze-thaw process can be utilized to prepare and store cell-laden hydrogels with adjustable mechanical properties.