Isolation and Co-culture of Cord Blood Stem Cells

CD34⁺ cells were isolated from fresh umbilical cord blood after written consent. Isolation of CD34⁺ cells and the study were specifically approved by the Ethic Committee of RWTH Aachen University (Permit Number: EK187/08). For antagomiR experiments we used CD133⁺ cells, which were isolated from cord blood from DKMS Nabelschnurblutbank (Dresden, Germany). Isolation of CD133⁺ cells from fresh cord blood (DKMS Nabelschnurblutbank, Dresden, Germany) and the study were specifically approved by the local Ethics Committee of the Ärztekammer Nordrhein (Permit Number: EK103/2011). In brief, mononuclear cells were separated by density gradient centrifugation and CD34⁺ or CD133⁺ cells were enriched using MicroBead Kits according to the manufacturer’s instructions (Miltenyi Biotec GmbH, Bergisch Gladbach, Germany) [27 (link)]. For co-culture conditions, MSCs were isolated from the caput femoris after the patient’s written consent and cultivated as described before [4 (link),28 ]. Isolation of MSCs from bone marrow and the study were specifically approved by the Ethic Committee of RWTH Aachen University (Permit Number: EK128/09). MSCs were seeded as feeder cells between passages 3 to 6 (10 to 15 population doublings).