The Effect of Storage Time on Adipose-Derived Stem Cell Recovery from Human Lipoaspirates

Multipotent adipose-derived stromal/stem cells (ASCs) can be isolated with high yield from human subcutaneous lipoaspirates. This study reports our experience isolating, expanding, differentiating and immunophenotypically characterizing ASCs over a period of 4 days after having surgically obtained the lipoaspirate samples. The ultimate goal is to understand how to optimize the consistent isolation of ASCs from lipoaspirates. The length of time between adipose tissue harvest and processing will need to be systematically evaluated with respect to cell yield, viability, and function since some distance is likely to exist between the plastic surgeon's office where lipoaspiration is performed and the current Good Manufacturing Practices (cGMP) laboratory where the ASCs are isolated. The objective of this study was to determine the effect of time delays on the yield and function of ASCs after collagenase digestion. We were able to isolate ASCs from lipoaspirates up to 72 h after the surgical procedure. The ASCs isolated on sequential days after the original tissue harvest proliferated, differentiated and maintained cell surface markers. We found that the initial 24-hour period is optimal for isolating ASCs with respect to cell yield and that there was no significant difference between ASC cell proliferation and differentiation ability within this period of time. In contrast, each of these parameters declined significantly for tissues maintained at room temperature for 48 or 72 h prior to isolation. These findings should be considered in the future development of standard operating procedures for cGMP processing of clinical-grade human ASCs.