Directed differentiation of embryonic stem cells: Genetic and epigenetic methods

Abstract

Embryonic stem cells are derived from the inner cell mass of the pre-implantation blastocyst, and can both self-renew and differentiate into all the cells and tissues of the body. The embryonic stem cell is an unsurpassed starting material to begin to understand a critical, largely inaccessible, period of development, as well as an important source of cells for transplantation and gene therapy. Despite their potential, attempts to obtain specific cell types from embryonic stem cells have been only partially successful because many of the growth factor combinations and developmental control genes involved in cell type restricted differentiation are unknown. This article summarizes some of the recent advances in promoting lineage restricted differentiation of embryonic stem cells, focusing on growth factor manipulation, or genetically altering embryonic stem cells to produce a desired phenotype. The two approaches epitomize current scientific concerns regarding the therapeutic use of these cells; genetic alterations will produce more pure cells with the risk of increasing the likelihood of malignant transformation; epigenetic methods for the manipulation of stem cell phenotype are often incomplete and remaining pluripotent cells are likely to form teratomas. As more is known about lineage specification during development, it will be possible to more precisely control cell type specification.

Retinoic acid inhibits leukemia inhibitory factor signaling pathways in mouse embryonic stem cells

“…Cultured ES cells can generate extra-embryonic cell types and derivatives of the three primary germ layers, ectoderm, mesoderm, and endoderm (Dushnik-Levinson and Benvenisty, 1995;Niwa et al, 2000;O'Shea, 2001;Fujikura et al, 2002). We (Chen and Gudas, 1996) have shown that RA induces differentiation into an extraembryonic epithelial cell type called primitive endoderm and causes growth arrest of ES cells in the presence of LIF, thereby overriding the LIF-induced signaling pathways which otherwise maintain selfrenewal of ES cells.…”

Cell-based Therapeutic Approaches for Parkinson's Disease: Progress and Perspectives

“…Numerous research .groups are currently involved with improving and modifying the existing basic in vitro differentiation protocols, and the results achieved are encouraging II4, 116,2837. Regarding the protocols based on manipulations of the hESC genome, these provide interesting scientific possibilities 79,142,209,2707 (see also 7947). However, from the clinical perspective, manipulations of this nature raise important ethical and safety concerns.…”

Concise Review: The Potential of Stem Cells for Auditory Neuron Generation and Replacement

“…Furthermore, the differentiation of a homogeneous population of cells has been problematic due to the routine production of multiple cell types using differentiation protocols [85]. For cell transplantation studies to be successful, it will be important to establish robust protocols for the production of pure populations of cells [16, 47, 85, 86].…”