| There has been significant interest in the literature on the possibility of using red blood cells (RBCs) derived from umbilical cord blood (cord RBCs) for neonatal transfusions. Low stability of cord RBCs during hypothermic storage necessitates the development of a cryopreservation method to prevent fast deterioration of these cells and create a stable supply for clinical transfusions.;The goal of this work was to understand the physiology of cord RBCs from a cryobiological perspective. Investigations were conducted on several levels, from assessing the initial quality of cord RBCs after their isolation from cord blood, to the determining the cryobiological parameters of the cord RBC membrane.;Results indicated that whole cord blood can be stored at room temperature for up to 65 hours without significant decrease in cord RBC quality. Cord blood:anticoagulant volume ratio was found to be a major determinant of cord RBC quality. I developed a new method to measure rapid osmotically-induced changes in RBC volume, which is based on the direct relationship between RBC volume and the intensity of autofluorescence of intracellular hemoglobin. This method was used to determine osmotic parameters of cord RBCs, such as the osmotically inactive fraction of cell volume, osmotic permeability to water and the cryoprotectant glycerol, the Arrhenius activation energies for water and glycerol permeabilities, and osmotic tolerance limits were determined. The permeability of cord RBCs varied, in comparison to adult RBCs, depending on temperature and osmolality. Cord RBCs appeared to be more osmotically resistant to swelling than adult RBCs. When cryopreserved using standard high glycerol – slow cooling method designed for adult RBCs, cord RBCs showed lower recovery compared to adult RBCs.;This thesis provides all pieces of a puzzle required to create the cryopreservation technique for cord RBCs in future, starting from their initial quality upon isolation from umbilical cord blood and ending with cryobiological parameters of cord RBC membrane. If a successful cryopreservation technique for cord RBCs is created, these cells can be turned from a waste product into a superior blood product for intrauterine and neonatal transfusions that will significantly improve prenatal and postnatal medical care. |
