Bone Marrow Stromal Cells and Hematopoiesis

Abstract

Five clonal stromal cell lines were established from 6-week-old human long-term bone marrow cultures (KM-101-105). They expressed none of the cell surface antigens characteristic of hematopoietic cells and endothelial cells, and showed different radiosensitivity at a low dose rate of irradiation. These cell lines produce hematopoietic growth factors (IL-6, G-CSF, M-CSF, GM-CSF, and EPA) and adhere to the hematopoietic cells from established cell lines and primary bone marrow cultures. Transfer of Lucifer Yellow CH was observed between the primary or established stromal cells, and their neighboring cells. The dye injected into the stromal cells sometimes moved into the attached round hematopoietic cells in primary bone marrow culture, and even in coculture of KM cells, and established hematopoietic cells. These results suggest that marrow stromal cells modulate hematopoiesis through the secretion of hematopoietic diffusible factors, direct stromal cell-hematopoietic cell contact, and intercellular gap junctions.