Graft clonogenicity and intensity of pre-treatment: factors affecting outcome of autologous peripheral hematopoietic cell transplantation in patients with acute myeloid leukemia in first remission

Direct conversion of human fibroblasts to multilineage blood progenitors

As is the case for embryo-derived stem cells, application of reprogrammed human induced pluripotent stem cells is limited by our understanding of lineage specification. Here we demonstrate the ability to generate progenitors and mature cells of the haematopoietic fate directly from human dermal fibroblasts without establishing pluripotency. Ectopic expression of OCT4 (also called POU5F1)-activated haematopoietic transcription factors, together with specific cytokine treatment, allowed generation of cells expressing the pan-leukocyte marker CD45. These unique fibroblast-derived cells gave rise to granulocytic, monocytic, megakaryocytic and erythroid lineages, and demonstrated in vivo engraftment capacity. We note that adult haematopoietic programs are activated, consistent with bypassing the pluripotent state to generate blood fate: this is distinct from haematopoiesis involving pluripotent stem cells, where embryonic programs are activated. These findings demonstrate restoration of multipotency from human fibroblasts, and suggest an alternative approach to cellular reprogramming for autologous cell-replacement therapies that avoids complications associated with the use of human pluripotent stem cells.

Factors affecting neutrophil recovery after autologous bone marrow-derived stem cell transplantation in patients with acute myeloid leukemia

Bone marrow is currently regarded as the most appropriate source of stem cells for patients with acute myeloid leukemia (AML) undergoing autologous transplants. A total of 55 adult patients with AML in first complete remission receiving autologous bone marrow-derived stem cell (BMSC) transplantation (BMSCT) were analyzed to determine factors affecting the rate of neutrophil recovery. All patients were treated with standard induction and three to four courses of consolidation chemotherapy and, after collection of BMSC, conditioned with BuCy2. The median time to neutrophil reconstitution was 30 (10-62) days and was delayed in 24 patients. Neutrophil recovery was faster in patients who had received granulocyte-macrophage progenitors (CFU-GM) dose >23.5 x 10(4)/kg, CD34(+) cells >3.2 x 10(6)/kg, and mononuclear cells (MNCs) >3 x 10(8)/kg. The speed of neutrophil recovery correlated with the number of transplanted CFU-GM progenitors (P = .0077) and MNCs (P = .0015). CFU-GM progenitors dose was the only factor close to significance in univariate analysis of neutrophil engraftment. Probability for neutrophil recovery was higher in patients transplanted with a higher dose of MNCs. These data suggested that the content of CFU-GM progenitors and MNCs within the bone marrow graft was the most important factor for the quality of neutrophil recovery after autologous BMSCT in AML patients.