A collaborative project between The University of Cambridge, the European Union ITN project SNAL and the independent research and consultancy division of the Biopharma group has used biomimetic calcium phosphate apatites to improve the freeze-drying and rehydration of red blood cells.
The development of blood transfusion techniques was a major boon to medicine, but depends on the successful preservation of blood products.
Refrigerated red blood cells (rbcs) may have a shorter shelf life than first thought, making freeze-drying (lyophilising) an interesting preservation alternative, especially for disaster zones lacking refrigeration. However, rbcs seem particularly prone to the structural, chemical and osmotic damage caused by ice crystal growth and the concentration of solutes.
Cryoprotectants can help protect cells during freezing and rehydration and a study carried out by the independent research and consultancy division of the Biopharma group, in collaboration with the University of Cambridge, using the disaccharide cryoprotectant trehalose, has achieved a cell survival rate of 96%.
However, haemoglobin oxidation levels were only at 60%. Altering the preservation formulation could produce better oxidation levels but at the expense of cell survival.
They hypothesised that poor trehalose cell penetration could be limiting cryoprotectant effectiveness and another series of experiments were undertaken with the European Union ITN project SNAL incorporating synthetic biomimetic calcium phosphate apatites, which have intrinsic biocompatibility and nanometer dimensions. The thought being that apatites would interact with cell membranes to allow greater trehalose penetration and more effective cryoprotection.
Three test groups were run comparing rbcs freeze-thawed in a trehalose-apatite-saline solution with cells freeze-thawed in PBS-trehalose and apatite-trehalose. The survival rate was significantly improved in the trehalose-apatite-saline suggesting that the apatite is augmenting the trehalose cryoprotectant action, potentially by increasing cell permeability.
Further studies are underway to test this, but hopes are that this will improve the freeze-drying of rbcs, making this a viable preservation method for medical purposes.