The field of stem-cell biology has been catapulted forward by the startling development of reprogramming technology. The ability to restore pluripotency to somatic cells through the ectopic co-expression of reprogramming factors has created powerful new opportunities for modelling human diseases and offers hope for personalized regenerative cell therapies. While the field is racing ahead, some researchers are pausing to evaluate whether induced pluripotent stem cells are indeed the true equivalents of embryonic stem cells and whether subtle differences between these types of cell might affect their research applications and therapeutic potential.

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The promise of induced pluripotent stem cells in research and therapy

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.

/pdf/screening-ethnically-diverse-human-embryonic-stem-cells-53hrlak737.pdf

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

Derivation and feeder-free propagation of human embryonic stem cells under xeno-free conditions

Establishment of a Brazilian line of human embryonic stem cells in defined medium: implications for cell therapy in an ethnically diverse population.

The use of stem cells for regenerative medicine has captured the imagination of the public, with media attention contributing to rising expectations of clinical benefits. Human embryonic stem cells (hESCs) are the best model for capital investment in stem cell therapy and there is a clear need for their robust genetic characterization before scaling-up cell expansion for that purpose. We have to be certain that the genome of the starting material is stable and normal, but the limited resolution of conventional karyotyping is unable to give us such assurance. Advanced molecular cytogenetic technologies such as array comparative genomic hybridization for identifying chromosomal imbalances, and single nucleotide polymorphism analysis for identifying ethnic background and loss of heterozygosity should be introduced as obligatory diagnostic tests for each newly derived hESC line before it is deposited in national stem cell banks. If this new quality standard becomes a requirement, as we are proposing here, it would facilitate and accelerate the banking process, since end-users would be able to select the most appropriate line for their particular application, thus improving efficiency and streamlining the route to manufacturing therapeutics. The pharmaceutical industry, which may use hESC-derived cells for drug screening, should not ignore their genomic profile as this may risk misinterpretation of results and significant waste of resources.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2010.0343.focus

Safety paradigm: genetic evaluation of therapeutic grade human embryonic stem cells

To the Editor: Human embryonic stem-cell research may lead to new methods of drug discovery, insights into mechanisms of disease, and eventually, cellular therapies. The potential benefit to patient populations may depend partially on the diversity of the stem-cell lines that are available for research and clinical use. However, investigators have been unable to target their research to diverse subgroups of existing lines or to ensure the inclusion of lines from the human populations most relevant to their diseases of interest, because almost no information has been available on the human population origin of existing stem-cell lines. Therefore, with the . . .

Kristina Harter

Papers

Lack of Population Diversity in Commonly Used Human Embryonic Stem-Cell Lines