Genetically modified CD34+ cells do not contribute to the mesenchymal compartment after autologous transplantation in the baboon

BackgroundThere is ongoing controversy about the transdifferentiation of hematopoietic stem cells (HSC) into different tissues such as mesenchymal cells. This transdifferentiation or ‘plasticity’ would be an appealing concept for many therapeutic strategies. While studies in the murine model show encouraging results, reports from clinical allogeneic stem cell transplantations do not support the concept of HSC plasticity. Our aim was to determine whether transplantation of transduced autologous marrow CD34+ cells leads to long-term engraftment of gene-marked cells with mesenchymal characteristics in the baboon.MethodsWe analyzed marrow of two baboons that had received green fluorescence protein (GFP)-marked CD34+ autologous marrow cells after myeloablative conditioning. Marrow was obtained 1 and 2.5 years after transplantation and adherent CD11a– (pan-leukocyte Ab) cells were cultured for 3 weeks. Cultures were then analyzed by flow cytometry and fluorescence microscopy for the presence of GFP+ cells. For ...