Cells present in processed lipoaspirate tissue are used to treat patients. Methods of treating patients include processing adipose tissue to deliver a concentrated amount of stem cells obtained from the adipose tissue to a patient. The methods may be practiced in a closed system so that the stem cells are not exposed to an external environment prior to being administered to a patient. The system comprises a first filter adapted to retain adipose-derived stem cells and a cell concentrator comprising a centrifuge or a spinning membrane.
