High dose chemotherapy followed by peripheral blood hematopoietic stem cell (PBSC) transplantation is frequently used for treating various hematologic malignancies. To facilitate this process, autologous PBSC are typically collected, cryopreserved and stored for some period of time. Current PBSC cryopreservation requires the use of molar concentrations of the cryoprotectant additive dimethyl sulfoxide (DMSO). Typically, frozen-thawed cells are transplanted back into patients along with DMSO. However, reinfusion of DMSO has long been associated with various adverse events, ranging from skin flushing, headache, fever, dyspnea, abdominal cramping, nausea, and diarrhea to more sever effects such as, hemolysis, cardiovascular symptoms and cerebrovascular ischemia leading to neurological events. These can result in increased morbidity, prolonged hospitalization, and increased treatment-related costs. Currently, when removal of DMSO is attempted, the procedures typically involve cell """"""""washing"""""""" using centrifugation. These methods introduce mechanical forces and osmotic stress causing cell packing/clumping and potential significant cell loss. They also require additional laboratory staff as well, and take between 3 and 4 hours of work per patient, which makes the procedure more expensive and practically difficult for many institutions. Finally, it is difficult to keep the cells in a """"""""closed"""""""" system during cell washing, which may lead to contamination. It is the goal of this proposal to refine and optimize an automated, portable, closed-system diffusion-driven washing device for use in clearance of DMSO from PBSC, to prevent infusion of DMSO into patients during clinical transplant without loss of cell numbers or cell functionality. In this Phase I research, the device will be optimized for effective clearance of DMSO from cell suspension solutions while allowing high cell recovery with maintenance of cell functional viability as assessed by in vitro clonogenic ability as well as engraftment in a NOD/SCID mouse model. ? ?