Abstract
Abstract 4815
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).
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.
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.
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
