Influence of donor age on induced pluripotent stem cells

Developers

Valentina Lo Sardo, William Ferguson, Kristin K Baldwin, Ali Torkamani, etc.

Description of the technology

Induced pluripotent stem cells (iPSCs) are being pursued as a source of cells for autologous therapies. However, this approach has the risk that epigenetic aberrations and mutations in the donor cells will be carried through to iPSCs and their derived tissues, resulting in increased tumorigenicity or dysfunction. iPSCs intended for autologous therapy can be produced from the somatic cells of aged patients. It is important to understand how age influences on iPSCs. The rare or unique somatic mutations in these cells can be invisible in bulk DNA sequencing studies. iPSCs can capture these rare changes in process of reprogramming. Thus, reprogramming enables high-resolution detection of rare somatic mutations without the errors and noise inherent to single-cell whole-genome sequencing.

In the technology, this approach was applied to assess the impact of age on rare exomic mutations in blood cells and iPSC lines derived from them. To explore the impact of age on iPSC quality, the developers of this technology produced iPSCs from blood cells of 16 donors aged 21–100. Then they carried out systematic investigations of the influence of donors’ age on the dynamics, а genetic and epigenetic changes of iPSCs.

The results showed that iPSCs from older donors retain an epigenetic signature of age based on DNA methylation at CpG sites. This signature can be reduced through passaging. Clonal expansion via reprogramming also enabled the discovery of somatic mutations present in individual donor cells, which were missed by bulk sequencing methods. It was shown that exomic mutations in iPSCs increase linearly with age, and all iPSC lines analyzed carry at least one gene-disrupting mutation. Several of these mutations have been associated with cancer or dysfunction. Unexpectedly, it was discovered that elderly donors (>90 yrs) harbored fewer mutations than predicted, likely due to a contracted blood progenitor pool. These studies establish that donor age is associated with an increased risk of abnormalities in iPSCs. Thus, these investigations serves as new source of information for clinical development of reprogramming technology.

Practical application

The technology will be highly useful for clinical development of cell reprogramming technology.
The performed systematic study of the effect of age and ageing on the genetic and epigenetic dynamics of iPSCs relied on the efficient methodology, used in this technology, for reprogramming peripheral blood mononuclear cells (PBMCs) of elderly individuals.

This work highlights new ideas for clinical translation of reprogramming techniques to the clinic and offers an approach for investigating the impact of age on the epigenetic and genetic features of iPSCs and somatic cell.

Laboratories

• Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla (USA)
• The Scripps Translational Science Institute, Scripps Health and The Scripps Research Institute, La Jolla (USA)

Links

Publications

• Lo Sardo, v. et al. «Influence of donor age on induced pluripotent stem cells» Nature Biotechnology (2016), doi:10.1038/nbt.3749 [Advance online publication].
• Erikson, G.A. et al. «Whole-Genome Sequencing of a Healthy Aging Cohort." 165.4 Cell. (2016): 1002−1011.
• Boland, M.J. et al. «Generation of mice derived from induced pluripotent stem cells." 69 J Vis Exp. (2012): e4003.