The Effect of HSA and Hematocrit on the Cake Collapse Temperature of Lyophilized Red Blood Cells by

approved: ____________________________________________________________ Adam Z. Higgins Freeze-drying, or lyophilization, has shown great promise in addressing many of the logistical challenges of storing and preserving red blood cells (RBCs). A crucial part of any future RBC lyophilization protocol is the primary drying temperature, which affects the sample drying rate and the dried cake’s ability to form a stable glassy solid which is critical to long-term RBC survival. The optimal temperature for primary drying is just below the temperature at which the porous structure of the cake begins to collapse, known as the cake collapse temperature. Therefore, this study utilized Freeze-Dry Microscopy of intracellular Trehalose-loaded RBC suspended in a buffer solution containing Human Serum Albumin (HSA) to determine the effect of both RBC and HSA concentration on the measured cake collapse temperature. It was found that increasing RBC concentration from 5% to 20% hematocrit raised the cake collapse temperature from -36.4°C ± 0.3 to -34.8°C ± 0.2, while increasing HSA concentration from 0 to 5% (w/v) raised the cake collapse temperature from -34.8°C ± 0.2 to -20.4°C ± 1.5. This data provides a basis for future study of the relationship between cake collapse and overall cell survival, with the object of building a clinically-viable RBC lyophilization protocol.