*2.2. Cell Isolation (Single and Dual Method)*

Mononuclear cells (MNC) were isolated by density gradient centrifugation using Lymphocyte Separation Medium (LSM; 1.077 g/L, PAA Laboratories GmbH, Pasching, Austria). CD133<sup>+</sup> and CD271<sup>+</sup> stem cells were enriched by positive magnetic selection using the magnet activated cell sorting (MACS) system (Miltenyi Biotec, Bergisch Gladbach, Germany). In case of CD133<sup>+</sup> direct labeling was applied and indirect labeling for CD271<sup>+</sup> cells (CD271-APC/anti-APC-microbeads; all Miltenyi Biotec). Purified stem cells were appropriately employed in further in vitro and in vivo experiments. For the dual method, the CD133<sup>+</sup> population was isolated from the CD271– fraction and vice versa.
