A New Ball for an Old Trick: Paramagnetic Cell Sorting of Human Mesenchymal Stem Cells from Adipose Tissue

Adipose tissue-derived mesenchymal stem cells (ASCs) may be isolated in clinically useful quantities without in vitro expansion. The purpose of this study is to validate a novel method for the enrichment of primary ASCs using paramagnetic beads. Primary rabbit anti-mouse antibodies were bound to paramagnetic microbeads. Secondary antibodies, selective for ASCs, were then bound to the primary antibodies to construct so-called paramagnetic immunobeads (PIBs). PIBs were then added to fresh human lipoaspirate to create ASC-PIB conjugates (aPIBS) over 10 minutes. A hand-held magnet was then placed adjacent to the lipoaspirate-aPIBs mixture, and over the next 10 minutes, the aPIBs were precipitated. Live cell count per mL of lipoaspirate was 9.6 x 104. Scanning electron microscopy revealed precipitates consistent with aPIBs. Flow cytometry identified cell-bound markers for CD90 and CD105 while culture confirmed tri-lineage differentiation, all attributes diagnostic of ASCs. This study validates that functional ASCs may be isolated from lipoaspirate by magnetic enrichment in 20 minutes. As both the harvest of adipose tissue by liposuction and this ASC enrichment technique do not require electricity, fresh primary therapeutic ASCs may be isolated in any point-of-care setting, even in developing countries.