Splenectomy Influences Homing of Transplanted Stem Cells in Bone Marrow–Ablated Mice

Cell mobilization, a process that influences circulation, margination, and finally, homing play key roles in the regeneration processes mediated by stem cells. Recent studies as well as prior studies from our group indicate an important role of the spleen in hematopoietic reconstitution, but to date the role of the spleen in hematopoietic reconstitution has been unclear and it has not been precisely documented in ablated animals. Therefore, we undertook the present study to define more closely the role of the spleen in hematopoietic reconstitution in lethally irradiated mice. After transplantation of irradiated mice with lacZ+-marked lin−/CD117+ bone marrow cells, we compared splenectomized mice (TS, splenectomy performed prior to irradiation) to nonsplenectomized, irradiated mice (TN) as well as to normal (unirradiated) mice. Impaired hematopoietic reconstitution was observed in TS mice. Splenectomy markedly altered the distribution of hematopoietic stem cells, as demonstrated by fluorescence-activated c...