Stage-specific culture of preB cells in porous hydroxyapatite ceramics

B cells differentiate in bone marrow from hematopoietic stem cells to immature B cells under the influence of bone marrow microenvironment. In in-vitro culture of B lineage cells, the stromal cell line can substitute for bone marrow microenvironment, supporting preB cells in the presence of interleukin 7 (IL-7). Because we consider that stromal cell culture on the flat plate is not enough to modify the bone structure, porous hydroxyapatite ceramics (HA) on that osteogenic differentiation occurred by bone marrow stromal cells were utilized for mimicking bone marrow microenvironment. Bone marrow cells and spleen cells were cultured on porous HA coated with a stromal cell line in the presence of IL-7. After 7 days culture, new population of preB cells were appeared, which are characteristic for next 3 items. 1). B220 low, BP1⁺ and CD43⁺ preB cells. 2) The surrogate light chain (VpreB and Lambda 5) positive preB cells were present. 3). PreB cells from spleen cells of a 7 weeks old adult mouse were populated. It is extremely interesting to note that this is the first demonstration of the presence of preB cells derived from adult spleen. All established preB cells can differentiate into IgM⁺ immature B cells. We speculate that porous HA coated with stromal cells can stabilize fragile cells specifically responding IL-7, demonstrating that porous HA provides different circumstances compared with flat plates.