The ability to expand hematopoietic stem cell populations in vitro would be of obvious advantage in both autologous and allogeneic bone marrow transplantation. Stem cell propagation requires interaction with adherent stromal support cells and can be performed in conventional tissue culture and on floating nylon mesh screens. The perfusion-based bioreactors currently available are capable of supporting cell growth at extremely high density and greatly improve cell performance but do not lend themselves to recovery of viable cells. The system is based on an array of flat membranes which can both support growth of purified stromal cell lines, and allow harvesting of viable non-adherent cells. The system will not only provide a means for progenitor cell growth and differentiation, but will also provide a model for studying other questions of hematological interest.Awardee's statement of the potential commercial applications of the research:Commercial applications include the production of stem cells for bone marrow transplantation, stand alone bioreactor systems for production and viable recovery of various types of adherent and non-adherent cells.National Heart, Lung and Blood Institute (NHLBI)