Figure 1.

Immunophenotypic identification and characterization of BM stromal cells. Panels (A–H) illustrate the immunophenotypic pattern of expression of classical stromal cell-associated markers on mesenchymal stem cells (MSC) and endothelial cells (EC). MSC (blue dots) and EC (red dots) shown in all panels were identified as CD81^hi, (CD73^hi), and CD45⁻ cells (B–D), which typically co-expressed MSCA1⁺, CD271⁺, and CD10^hi in the absence of CD34 (MSC), or they were CD34⁺ in the absence of MSCA1, CD271, and CD10 expression (EC), respectively. Other BM cells are depicted as grey events. Panels (I–P) illustrate how BM stromal cells (EC and MSC) were specifically identified and classified after staining with the EuroFlow BCP-ALL MRD antibody panel (Tube 2).