Endocrine Abstracts

Human embryonic stem (ES) cells are pluripotent cells derived from in vitro fertilized human blastocysts. These cells are a unique scientific and medical resource as they could help us understand early human development, and serve as a source of cells for transplantation medicine. It is estimated that in the USA alone 3,000 patients die every day from diseases that are potentially treatable with embryonic stem cell-derived tissues. We show that in culture human ES cells can reproducibly differentiate into embryoid bodies comprising the three embryonic germ layers. Some of these embryoid bodies were pulsating in rhythm and express myocardium markers. In addition, we examined the potential of eight growth factors to affect the differentiation of human ES cells. Differentiation of the cells was assayed by expression of various cell specific molecular markers that cover all embryonic germ layers and a dozen different tissues. Each growth factor has a unique effect that may result from directed differentiation and/or cell selection. In order to expand our study we have also used DNA micro-arrays. Our analysis allows us to point out the genes and tissues mostly affected by the different growth factors, and to compare the effects of the different factors in a genomic scale. Recently, we were able to genetically modify human ES cells and thus to label and sort out cells at different stages of their differentiation. In addition, using genetically labeled human ES cells we have examined the differentiation of human ES cells in the developing chick. The human cells were shown to proliferate, differentiate and migrate into the chick tissues. This analysis sets the stage for differentiation of human ES cells and isolation of specific cell types for cellular transplantation.