LRCs redistribute to rEnd. (A) Mononuclear cells from MBA (n = 3 patients) were treated with melphalan (“Preclinical drug treatment studies”) and grown in rBM for 21 days, and the extent of the malignant outgrowth was measured by RQ-PCR. MBA generated MM progeny and LRCs comparable with those from BM; the majority of MBAs also generated stromal layers. Preculture ex vivo BMCs and MBA cells were used as controls. Horizontal lines represent medians. (B,C) BMCs were labeled with CFSE (green) and cultured for 21 days. (B) rBM was stained with DAPI (blue inset) to detect total cells in the cultures, and the position of the brightly staining CFSE⁺ LRCs was analyzed by confocal microscopy (original magnification 100×) as indicated in “Microscopy.” Representative images from 8 individually analyzed patient samples. (C) The rBM layer was removed, and the cells at rEnd were fixed and stained with N-cadherin. CFSE⁺ LRCs (green) shown in contact with an N-cadherin⁺ stromal cell (red), DAPI stained nuclei (blue). Representative 10 images from 3 individually analyzed patients.