Exposure to a MRI-type high-strength static magnetic field stimulates megakaryocytic/erythroid hematopoiesis in CD34+ cells from human placental and umbilical cord blood.

The biological response after exposure to a high-strength static magnetic field (SMF) has recently been widely discussed from the perspective of possible health benefits as well as potential adverse effects. To clarify this issue, CD34+ cells from human placental and umbilical cord blood were exposed under conditions of high-strength SMF in vitro. The high-strength SMF exposure system was comprised of a magnetic field generator with a helium-free superconducting magnet with built-in CO2 incubator. Freshly prepared CD34 cells were exposed to a 5 tesla (T) SMF with the strongest magnetic field gradient (41.7 T/m) or a 10 T SMF without magnetic field gradient for 4 or 16 h. In the harvested cells after exposure to 10 T SMF for 16 h, a significant increase of hematopoietic progenitors in the total burst-forming unit erythroid- and megakaryocytic progenitor cells-derived colony formation was observed, thus producing 1.72- and 1.77-fold higher than the control, respectively. Furthermore, early hematopoiesis-related and cell cycle-related genes were found to be significantly up-regulated by exposure to SMF. These results suggest that the 10 T SMF exposure may change gene expressions and result in the specific enhancement of megakaryocytic/erythroid progenitor (MEP) differentiation from pluripotent hematopoietic stem cells and/or the proliferation of bipotent MEP. Copyright 2009 Wiley-Liss, Inc.