Prospectively isolated mesenchymal stem/stromal cells are enriched in the CD73+ population and exhibit efficacy after transplantation.

Mesenchymal stem/stromal cells (MSCs), which reside in the bone marrow (BM) and various other tissues, can self-renew and differentiate into mesenchymal lineages. Many groups have harvested rat MSCs (rMSCs) from rat BM (rBM) by using a flush-out procedure and have evaluated surface marker expression after long-term culture. However, MSCs gradually differentiate during expansion and exhibit altered proliferation rates, morphological features and functions in vitro. Variations in MSC isolation methods may alter the effectiveness of therapeutic applications. Here, on the basis of CD29 (Itgb1) and CD54 (Icam1) expression, we prospectively isolated a population with a high colony-forming ability and multi-lineage potential from the rBM, and we demonstrated that most of these cells expressed CD73. Successful engraftment of rMSCs was achieved by using a fluorescence-conjugated anti-CD73 antibody. In humans and mice, MSCs were also purified by CD73, thus suggesting that CD73 may serve as a universal marker for prospective isolation of MSCs. Our results may facilitate investigations of MSC properties and function.