Protection of CANARY cells after drying and rehydration correlates with decrease in apoptotic cell death

CANARY cells are genetically engineered murine B cells that serve as a rapid detection system for various infectious pathogens. We are attempting to produce a stable dehydrated cellular product to make this system practical. A major source of damage to these cells during drying was identified as apoptosis. Trehalose, which protects mammalian cells during drying, was investigated with regard to its effect on apoptosis. B cells were loaded with trehalose and vacuum-dried. Trehalose reduced apoptosis during drying and rehydration, and when used in combination with a pan-caspase inhibitor OPH-109, the degree of apoptotic cell loss was further diminished. In this case, viability following rehydration reached 70%-80%. Surprisingly, trehalose alone blocked apoptotic cell death better than OPH-109 alone (45% versus 70% total apoptotic cells for trehalose- or OPH-109-treated samples, respectively, after drying to 0.3 g H₂O/g dry weight). Nevertheless, optimal viability was achieved when the cells were loaded and dried in the presence of both compounds. Only cells dried in the presence of trehalose responded to the CANARY bioassay. Trehalose did not decrease apoptosis in cells treated with high temperature or camptothecin. Thus, the inhibition of apoptosis during drying seems to be a specialized effect, and may be a secondary result of the other protective properties of trehalose.