Changes of Hematopoietic Stem Cells due to the Local Irradiation of the Maxilla in Mice

—A study of CD34⁺ cells and CD71⁺ cells—

Abstract

This study was to investigate the difference in influence on hematopoietic stem cells between the local irradiation (10Gy) to a portion of the maxilla and whole body irradiation (0.5, 1, 4 Gy, respectively) , in particular focusing on the CD34⁺ cells (hematopoietic stem cells) and CD71⁺ cells (cell that express transferrin receptor) in mice. We analyzed the absolute number of the lymphocytes, T cells, B cells, CD34⁺ cells and CD71⁺ cells in the spleen by using flow cytometry after the irradiation.
The following results were obtained: 1. In each whole-body irradiation group, B cells showed decrease at the early stage after irradiation. However, B cell recovered earlier than T cell, and showed increase compared with non-irradiation groups thereafter. CD34⁺ cells showed decrease at the early stage after irradiation. However CD34⁺ cells showed increase compared with non-irradiation groups thereafter. Moreover, CD71⁺ cells showed a similar result with CD34⁺ cells. 2. In the local irradiation groups, B cells recovered at the early stage after irradiation compared with T cells. B cells did not show any significant changes after irradiation, and CD71⁺ cells showed decrease at the early stage after irradiation. These results indicated that the number of lymphocytes recovers because of an increase of CD34⁺ cells (hematopoietic stem Cell) and CD71⁺ cells in whole-body irradiation group. On the other hand, it was suggested that the number of lymphocytes recovered even if neither CD34⁺ cells nor CD71⁺ cells increased in the local irradiation groups.