Screening ethnically diverse human embryonic stem cells identifies a chromosome 20 minimal amplicon conferring growth advantage

The International Stem Cell Initiative analyzed 125 human embryonic stem (ES) cell lines and 11 induced pluripotent stem (iPS) cell lines, from 38 laboratories worldwide, for genetic changes occurring during culture. Most lines were analyzed at an early and late passage. Single-nucleotide polymorphism (SNP) analysis revealed that they included representatives of most major ethnic groups. Most lines remained karyotypically normal, but there was a progressive tendency to acquire changes on prolonged culture, commonly affecting chromosomes 1, 12, 17 and 20. DNA methylation patterns changed haphazardly with no link to time in culture. Structural variants, determined from the SNP arrays, also appeared sporadically. No common variants related to culture were observed on chromosomes 1, 12 and 17, but a minimal amplicon in chromosome 20q11.21, including three genes expressed in human ES cells, ID1, BCL2L1 and HM13, occurred in >20% of the lines. Of these genes, BCL2L1 is a strong candidate for driving culture adaptation of ES cells

Efficient differentiation of human embryonic stem cells into a homogeneous population of osteoprogenitor-like cells

The use of human embryonic stem cells (hESC) in both research and therapeutic applications requires relatively large homogeneous populations of differentiated cells. The differentiation of three hESC lines into highly homogeneous populations of osteoprogenitor-like (hESC-OPL) cells is reported here. These cells could be expanded in a defined culture system for more than 18 passages, and showed a fibroblast-like morphology and a normal stable karyotype. The cells were strongly positive for the same antigenic markers as mesenchymal stem cells but negative for markers of haematopoetic stem cells. The hESC-OPL cells were able to differentiate into the osteogenic, but not into the chondrogenic or adipogenic, lineage and were positive for markers of early stages of osteogenic differentiation. When cultured in the presence of osteogenic supplements, the cells indicated the capacity to achieve, under inductive conditions, a mature osteoblast phenotype. The differentiation protocol is based on a monolayer approach, and does not require any exogenous factors other than fetal calf serum, or coculture systems of animal or human origin. This method is likely to be amenable to large-scale production of homogeneous osteoprogenitor-like cells and thus overcomes one of the major problems of differentiation of hESC, with important relevance for further cell therapy studies