Mesenchymal Stromal Cells Induce Ex Vivo Proliferation and Erythroid Commitment of Cord Blood Haematopoietic Stem Cells

A human bone marrow-derived mesenchymal stromal cell (MSCs) and cord blood-derived CD34+ stem cell co-culture system was set up in order to evaluate the proliferative and differentiative effects induced by MSCs on CD34+ stem cells, and the reciprocal influences on gene expression profiles Bone marrow-derived mesenchymal stromal cells (BM-MSCs) were seeded on a plastic support. Upon reaching 80% of confluence, previously isolated CD34+ cord blood-derived hematopoietic stem cells (CB-CD34+) were plated onto a MSCs layer. After 10 days of culture, cells grown in suspension were collected in plastic tubes, while adherent cells were harvested by trypsinization. Two different fractions of HSCs were obtained: the SN-fraction, representing the HSCs grown in the supernatant of the co-cultures, and the AD-fraction, representing the HSCs grown directly in contact with the stromal layer (co-coltured MSCs). Single cultures of BM-MSCs and CB-CD34+ cells served as controls, namely MSCs-alone and CB-alone