| The objective of this dissertation was to develop processes for the stabilization and lyophilization of two highly thermolabile biopharmaceuticals: human hematopoietic stem and progenitor cells (HPCs) and live attenuated viral vaccines.; As a first step toward preserving HPCs, we focus our efforts on overcoming the impermeability of cell membranes to trehalose followed by freeze-thawing. Permeabilization of cell membranes was accomplished by employing pore-forming proteins. We developed processes using a model CD34+ cell line (TF-1), which were later applied to human HPC derived from either bone marrow or umbilical cord blood (UCB). Colony forming units (CFU) generated from cells frozen and thawed with intra- and extracellular trehalose were essentially equivalent in size, morphology, and number to those generated by unfrozen cells. Additionally, there were no observable alterations in phenotypic markers of differentiation.; Cells containing trehalose were loaded into a freeze-dryer and removed during each step of the cycle to assess viability, as determined by a CFU assay. Lyophilized cells processed at 15 and 20 °C were stored at 25 °C for 4 wk or 5 mos at ambient conditions (temperature and light) without significant loss in clonogenic activity. Optimal parameters obtained with our model were used to lyophilize HPC derived from umbilical cord blood.; We also investigate the lyophilization of a live-attenuated enterovirus vaccine. These types of vaccines are a particular challenge because of the complexity of intact viruses. The objective of this study was to lyophilize a model enterovirus, designated AVP-704. Samples were loaded into a freeze-dryer and removed during each step of the cycle to identify where vaccine potency is lost. Vaccine potency was measured by a tissue culture infection dose 50 (TCID50) assay. In this study we demonstrate that AVP-704 liter following freeze-drying resulted in an acceptable processing loss (log 10 0.37 TCID50/mL).; These studies document that human HPCs loaded with trehalose not only survive lyophilization and reconstitution, but clonogenic activity is preserved after storage at 25°C or ambient temperature and light in a desiccated state. This type of flexible storage stability would allow HPCs to be shipped long distances and stored without refrigeration. Furthermore, we also demonstrate that thermolabile enteroviruses can be successfully lyophilized. |
