Global gene expression pattern difference between the high density and the regular density cultured rat bone marrow cells

In vitro expansion of endothelial progenitor cells (EPCs) remains a challenge in stem cell research and its application. We hypothesize that high density culture is able to expansion EPCs from bone marrow by mimicking cell-cell interactions of the bone marrow niche. To test the hypothesis, rat bone marrow cells were either cultured in high density by seeding or cultured in regular density. Flow cytometric analyses of the cells cultured for 15 days showed that high density cells exhibited smaller cell size and higher levels of marker expression related to EPCs when compared to regular density cultured cells. Global gene expression pattern difference between the high density and the regular density cultured cells was analyzed by a microarray assay.