A method of preparing a concentrated population of fresh adipose tissue-derived cells comprising stem cells and endothelial precursor cells for reintroduction into a patient, comprising: a) introducing adipose tissue comprising adipose-derived stem cells and endothelial precursor cells removed from a patient into a system configured to maintain a closed sterile fluid/tissue pathway by use of a pre-assembled, linked set of closed, sterile containers and tubing; b) processing said adipose tissue within said closed system by i. separating a cell population that comprises adipose-derived stem cells and endothelial precursor cells from mature adipocytes and connective tissue present in the adipose tissue that was removed from said patient within said system while maintaining said closed pathway such that there is depletion of the mature fat-laden adipocyte component of adipose tissue in said cell population that comprises adipose-derived stem cells and endothelial precursor cells; and ii. concentrating said adipose tissue-derived cells that comprise adipose-derived stem cells and endothelial precursor cells within said system while maintaining said closed pathway to obtain said concentrated population of fresh adipose tissue-derived cells, wherein the system is configured for processing the population of fresh adipose tissue derived cells comprising stem cells and endothelial precursor cells without removal from the system. a) introducing adipose tissue comprising adipose-derived stem cells and endothelial precursor cells removed from a patient into a system configured to maintain a closed sterile fluid/tissue pathway by use of a pre-assembled, linked set of closed, sterile containers and tubing; b) processing said adipose tissue within said closed system by i. separating a cell population that comprises adipose-derived stem cells and endothelial precursor cells from mature adipocytes and connective tissue present in the adipose tissue that was removed from said patient within said system while maintaining said closed pathway such that there is depletion of the mature fat-laden adipocyte component of adipose tissue in said cell population that comprises adipose-derived stem cells and endothelial precursor cells; and ii. concentrating said adipose tissue-derived cells that comprise adipose-derived stem cells and endothelial precursor cells within said system while maintaining said closed pathway to obtain said concentrated population of fresh adipose tissue-derived cells, i. separating a cell population that comprises adipose-derived stem cells and endothelial precursor cells from mature adipocytes and connective tissue present in the adipose tissue that was removed from said patient within said system while maintaining said closed pathway such that there is depletion of the mature fat-laden adipocyte component of adipose tissue in said cell population that comprises adipose-derived stem cells and endothelial precursor cells; and ii. concentrating said adipose tissue-derived cells that comprise adipose-derived stem cells and endothelial precursor cells within said system while maintaining said closed pathway to obtain said concentrated population of fresh adipose tissue-derived cells,