Abstract
Abstract 4815
Background and Aims:
We reported that acute myelogenous leukemia blasts and chronic myelogenous leukemia cells converted to stromal myofibroblasts to create an environment for the proliferation of leukemic cells in vitro and also in a non-obese diabetes/ severe combined immunodeficiency (NOD/SCID) murine bone-marrow in vivo. In normal hematopoiesis, hematopoietic stem cell (HSC) and stromal immature mesenchymal stem cell (MSC) are speculated to have a cross-talk, and some reports indicate that the HSC generates MSC, and also a specific fraction of MSC shares similar molecular expressions to that of HSC. We made a hypothesis that HSC might be generated from MSC. To make clear this issue, expression cloning was performed to isolate a molecule that stimulated bone-marrow stromal myofibroblasts to express hematopoietic stem cell marker, CD34. And, we also observed the effect of the isolated molecule to an adult human dermal fibroblast (HDF).
Materials and Methods:
cDNA-expression library was constructed using PHA-P-stimulated normal human blood lymphocytes, and the prepared plasmids were transfected to COS7 cells. After 3 days of culture, supernatants were added to the normal human bone-marrow-derived myofibroblasts (final 10%), and cells were further cultured for one week. RNA was extracted from the cultured myofibroblasts, and cDNA was synthesized. Positive clones were selected on CD34-expression with reverse transcription-polymerase chain reaction, and a single clone was isolated. The purified protein from the isolated single clone was added to HDF-culture, and the morphological changes and the expression of specific hematopoiesis-related proteins were analyzed.
Results and Discussion:
Isolated single clone was human interleukin 1β (IL-1β). When the purified IL-1β protein was added to the bone-marrow-derived myofibroblast cultures, cell growth was increased, and up-regulation of the expression of several hematopoietic specific proteins, including cytokine receptors and transcription factor SCL, was observed. Based on these observations, we determined the effect of IL-1β to HDF. When HDFs were cultured with human IL-1β for 3 weeks, the expression of granulocyte colony-stimulating factor (G-CSF)-receptor, and SCL was increased. When these IL-1β-stimulated cells were cultured in a non-coated dish, cells were floating, and budding of the cells was also observed. When HDF were cultured with IL-1β for 3 weeks, and then G-CSF and erythropoietin were added to the cultures, expression of transcription factor GATA-1 and CEBPA was significantly increased after one week. These observations indicate that IL-1β can stimulate to induce HDF toward hematopoietic cells. Now we determine the precise actions of human IL-1β to HDF using NOD/SCID transplantation model in vivo.
Disclosures:
No relevant conflicts of interest to declare.
Enhanced thrombopoietin but not G-CSF receptor stimulation induces self-renewing hematopoietic stem cell divisions in vivo