With increased activity of global terrorist organizations and a rise in illicit trafficking of radioactive materials, the threat of nuclear or radiological attacks has quickly grown. Bone marrow hematopoietic stem cells (HSCs) are easily damaged by radiation (HSCs are cells which can self-renew and differentiate to produce all mature blood cell types). Bone marrow (BM) failure (especially damage of HSCs and associated immunosuppression) is one of the major causes of death of victims after high-dose total body nuclear or radiological irradiation. HSCs transplantation, as one of countermeasures against radiation, is a potentially effective approach to re-constitute victim’s hematopoietic and immue system. Cryopreservation of HSCs and cultured/expanded hemapoietic progenitor cells (HPCs, committed to various cell lineages) are critical and indispensable for storage and banking of a large quantity of these cells for MHC matching to ensure the successful HSC transplantation (engraftment), therapy, as well as for transient protection from radiation-induced hematopoietic syndrome. The goal of this research is to develop novel technology (currently does not exist) to increase the quality and reduced the cost of cryopreservation of HSCs and cultured HPCs. Two specific aims were proposed to achieve this goal. Specific Aim 1 is to develop and validate a reliable, and low-cost “bax-in-box” (BIB) cooling system to achieve the optimal cooling rates for HSCs. A novel mini-module dialysis washing system will be used to remove cryoprotective agent, DMSO, from HSCs (DMSO is toxic to HSCs and human body. For many years, scientists and doctors have tried to remove DMSO from the stem cells using a procedure involving centrifugation but failed because the centrifugation procedure introduces mechanical forces and the osmotic stress causing cell packing/clumping, cell loss, and osmotic injury). Specific Aim 2 is to evaluate if the optimal cryopreservation technology developed (for human HSCs) from Specific Aim 1 can be used and applied for cryopreservation of cultured human and canine hematopoietic progenitor cells to support planned animal studies in the FHCRC/UW Center for Medical Countermeasures Against Radiation.