Application of ex vivo expanded hematopoietic stem cells stimulated with human umbilical venous endothelial cells for transplantation in children

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The aim of this study was to establish the ex vivo expansion of hematopoietic stem cells by co-culture system with human umbilical venous endothelial cells(HUVEC). After the establishment of the co-culture system with HUVEC, hematopoietic stem cells continuously grew and proliferated. However, several problems including how to maintain the function of endothelial cells for a long time, or how to make an attachment of stem cells effectively with endothelial cells via membrane filter.The aim of the next study was to clarify effects of INF-γ on monocytes and macrophages, using U937 monocytic cells. We investigated expressions of inflammation-related proteins such as MCP-1 (Monocyte chemoattractant protein-1,COX-2 (Cyclooxyganase-2), iNOS (inducible nitric oxide synthetase), Ferritin, CRP(C-reactive protein), AngiotensinII receptor-1(AT1R), Scavenger receptor type A(SRA) and Oxidized LDL receptor-1(LOX-1) with fluorescent immnocytochemical staining. Stimulation with INF-γ for 24 hours caused upregulation of all these proteins in U937 cells strongly. The fluorescent intensity of these proteins was increased by more than 150% of that in unstimulated cells. In comparison with TNF-α, which is one of proinflammatory cytokines, TNF-α did not give such striking effect on U937 cells. Moreover, INF-γ seemed to accelerate uptake of Dil labeled oxidized LDL and induced morphological changes like foam cells in some cells. These results demonstrate that IFN-γ could activate monocytes strongly and variously, and that effects of FN-γ could play important roles in disease such as hemophagocytic syndrome, macrophage activating syndrome and atherosclerosis.