Beneficial effect of intracellular trehalose on the membrane integrity of dried mammalian cells

Recently, there has been much interest in using trehalose and other small carbohydrates to preserve mammalian cells in the dried state as an alternative to cryopreservation. Here, we report on the successful preservation of plasma membrane integrity after drying, as a first step toward full preservation of mammalian cells. Trehalose was introduced into cells using a genetically engineered version of α-hemolysin, a pore-forming protein; the cells were then dried and stored for weeks at different temperatures with ∼90% recovery of the intact plasma membrane. We show that protection of the plasma membrane by internal trehalose is dose dependent and estimate the amount of internal trehalose required for adequate protection to be ∼10¹⁰ molecules/cell. In addition, a minimal amount of water (∼15 wt%) appears to be necessary. These results show that a key component of mammalian cells can be preserved in a dried state for weeks under mild conditions (-20°C and 5% relative humidity) and thereby suggest new approaches to preserving mammalian cells.