Tardigrades, also called water bears, are famous for their ability to survive nearly anything. They protect themselves in extreme environments using proteins that researchers have now developed into an efficient and effective strategy to preserve human red blood cells.
Blood cells are typically treated with glycerol to stop ice crystal formation during freezing. But glycerol must be removed before a transfusion, which causes cell damage. The tardigrade offers a simpler option: they have a protein called CAHS (cytosolic abundant heat-soluble), that it uses to keep itself going in extreme conditions. These proteins uniquely interact with trehalose, a sugar that stabilizes cell membranes and proteins.
Researchers at Northwestern Polytechnical University wanted to explore whether combining CAHS proteins and trehalose could protect red blood cells in mice better than glycerol could alone.
Rather than using the full-length CAHS protein, the researchers determined that a section provided the desired protective effect. When combined with trehalose at a low temperature and then frozen in liquid nitrogen, the two components changed the way ice formed and melted, shielding cells from damage. And after thawing the cells, the CAHS-trehalose can easily be washed away by centrifugation. Up to 89% of the mouse red blood cells preserved with the new method recovered fully, compared to about 82% of the cells frozen using glycerol.
When the team tested the new cryopreservation approach, they confirmed that the blood cells were biocompatible after being frozen, thawed and washed. In anemic mice, a transfusion with cryopreserved blood significantly improved their blood cell counts and hemoglobin levels without causing an inflammatory response.
The researchers hope that this work can help design better strategies for cryopreservation and even lead to protective strategies for blood that can function at room temperature.
Data from American Chemical Society