Derivation and Characterization of human Induced Pluripotent Stem Cells

Abstract

Cell biology is one of the most rapidly developing branches in modern biology. The most interesting stages in early embryonic development for cell biology are those when a large number of cells are pluripotent. Inner-cell mass of blastocyst can be cultivated in vitro, and these cells are called embryonic stem cells. They are able to differentiate into different types of cells and tissues. But the greatest interest for practical application is the return (reprogramming) of adult cells into the pluripotent state. In our study for the first time induced pluripotent cells were derived from human umbilical vein endothelial cells by genetic reprogramming. We showed that these cells are similar to embryonic stem cells in their morphology, function, and molecular level. We are the first to show that reprogramming sufficiently changes X-chromosome chromatin state, which is normally inactive in female endothelial cells, towards its activation, providing evidence that endothelial cells are reprogrammed at an epigenetic level.

Full Text

A multicellular organism develops from a single cell, a zygote, and becomes a complex of mutually supported tissue types during its individual development. The totipotent zygote cell and the terminally differentiated cell contain the same set of genetic information, but this information is achieved differently. Cellular programs of differentiation happen at the genetic and epigenetic levels. The zygote achieves a specified program and divides, and at a certain stage, cells begin to specialize. A blastocyst (about 3.5 days in mouse and 5.5 days in humans) has two types of cells and is a future embryo which has no physical connection with its mother’s organism. The inner cells will develop into the organism and all its tissues, and the outer layer of cells will develop into trophectogerm, which will interact with the mother’s organism. In vitro (in laboratory conditions) cultivated blastocyst inner-cell mass were called embryonic stem cells (ESC). In vitro ESC under appropriate conditions do not continue their program further; they stay in a pluripotent state for an unlimited time [1], but one can induce their controlled differentiation into the tissues of all three germ layers just by changing the culture’s conditions [2]. However, in the case of using these type of cells in therapy, the immunologic compatibility between the derived tissues and the recipient remains to be defined. Reprogramming individual somatic cells to a pluripotent state will be a perfect solution to this problem. For this purpose, the technologies of somatic cell nuclear transfer into the oocyte and fusion of the somatic cell with the pluripotent one were developed [3–5]. However, in 2006, S. Yamanaka [6] put forward a method of somatic cell genetic reprogramming to the pluripotent state.