Radiation Sensitivity of Megakaryocyte Colony-Forming Cells in Human Placental and Umbilical Cord Blood

Abstract

The in vitro radiation sensitivity of CFU-Meg isolated from human placental and umbilical cord blood was evaluated in plasma clot cultures stimulated by recombinant human cytokines, including thrombopoietin, the FLT3 ligand (FLT3LG), interleukin-3, interleukin-11 and stem cell factor. The CD34(+) cells were irradiated with X rays at a dose rate of 73 cGy/ min. The megakaryocyte colonies were identified by using an FITC-conjugated antibody to glycoprotein IIbIIIa and were classified into two groups based on colony size: large colonies (immature CFU-Meg) and small colonies (mature CFU-Meg). Treatment with thrombopoietin alone or in combination with FLT3LG and/or interleukin-11 gave exponential radiation survival curves (D(0) for immature CFU-Meg = 56-77 cGy, D(0) for mature CFU-Meg = 86 cGy-1.12 Gy), while marked shoulders were observed on the survival curves for colonies supported by the combination of thrombopoietin, interleukin-3 and stem cell factor (D(0) for immature CFU-Meg = 89- 98 cGy; D(0) for mature CFU-Meg = 1. 25-1.31 Gy). Our results showed that the immature CFU-Meg were more radiosensitive than the mature CFU-Meg and that the combination of cytokines, including thrombopoietin, interleukin-3 and stem cell factor, affected the radiation sensitivity of CFU-Meg to the same extent as with thrombopoietin alone or in combination with FLT3LG and/or interleukin-11.

Maternal and Neonatal Factors Associated with the High Yield of Mononuclear Low-Density/CD34+ Cells from Placental/Umbilical Cord Blood

“…Meanwhile, in order to overcome the limitations of hematopoietic stem/ progenitor cells contained in a CB unit, there has been ongoing research including the ex vivo expansion of hematopoietic stem/progenitor cells using a combination of cytokines (DiGiusto et al 1996;Shpall et al 2002) and clinical trials involving the combined transplantation of multiple CB units (Barker et al 2005). CB hematopoietic stem/progenitor cells are also used for research in various fields of biological science, such as drug sensitivity (Gribaldo et al 1999) or radiation sensitivity (Kashiwakura et al 2000(Kashiwakura et al , 2002(Kashiwakura et al , 2006aMonzen et al 2006). Furthermore, mesenchymal stem cells and somatic stem cells contained in CB have already been applied for bio-medical therapies and research in regenerative medicine (Kögler et al 2004;McNiece et al 2004;Hirata et al 2005;Ma et al 2005;Pozzi et al 2006).…”

Regulation of DNA damage response and cell cycle in radiation-resistant HL60 myeloid leukemia cells

“…During X-ray exposure, the dose intensity was evaluated using the probe with ionization chamber. Irradiated cells were cultured using the plasma clot technique described in a previous report (10) at 37˚C in a humidified atmosphere containing 5% CO 2 . On the eighth day from the start of irradiation, colonies consisting of >50 cells were counted using an inversion microscope.…”

The Promoting Activity on Human Megakaryocytopoiesis and Thrombopoiesis by Liquid Crystal-Related Compounds

“…14) This culture was plated onto 24-well cell culture plates at 0.3 ml/well, and then it was incubated at 37°C in a humidified atmosphere containing 5% CO 2 . On day 12, each well was fixed twice for 15 min with acetone and methanol (2 : 1).…”