Abstract
Decellularized heart valve tissues are receiving increased attention as matrix implants. Storage of these biological matrices in a dry state has clear economic and practical advantages compared to frozen storage. Long-term storage becomes available at room temperature without the need of liquid nitrogen or expensive freezer systems. We have investigated the effects of drying on heart valve scaffolds using sucrose as a protectant. First, the diffusion kinetics of sucrose in the scaffolds was studied using attenuated total reflection infrared spectroscopy. These studies indicated that the scaffolds can be homogeneously loaded with sucrose within several hours at 37 °C. After loading with sucrose, the scaffolds were either freeze- or vacuum-dried, and the structure was evaluated by histology staining. Freeze-drying in the absence of sucrose caused an overall disintegrated appearance of the histological architecture. Sucrose (5% w/v) protects during drying, but freeze-dried scaffolds were found to have a more porous structure, likely due to ice crystal formation. Rapid freezing, which reduces ice crystal size, was found to reduce the pore size. No pores were observed when samples were incubated in high concentrations of sucrose (80% w/v) and the overall architecture closely resembled that of fresh tissue. Vacuum drying, which lacks a freezing step, has the advantage that drying times are much shorter. Vacuum-dried tissue displayed an intact histological architecture similar to freeze-dried tissue. In conclusion, both freeze-drying and vacuum-drying hold promise for preservation of decellularized heart valve tissues and could possibly replace vitrification or cryopreservation approaches in the near future.
Published Version
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