Unique features of mutations revealed by sequentially reprogrammed induced pluripotent stem cells

Area of Science:

• Stem cell biology
• Genetics
• Developmental biology

Background:

• Viable mice can be generated from induced pluripotent stem cells (iPSCs).
• The long-term impact of accumulated mutations on iPSC developmental potential is not fully understood.

Purpose of the Study:

• To investigate the impact of accumulated somatic mutations on the developmental potential and viability of mice generated from serially reprogrammed induced pluripotent stem cells (iPSCs).
• To characterize the types and extent of genetic alterations accumulating during sequential reprogramming.

Main Methods:

• Utilized a Tet-on inducible reprogramming system for sequential generation of mice from iPSCs over multiple generations.
• Employed tetraploid blastocyst complementation for generating all-iPSC mice.
• Conducted whole-genome sequencing to identify accumulated single-nucleotide variations (SNVs) and copy-number alterations (CNAs).

Main Results:

• All-iPSC mice could be generated for up to six generations, but viability decreased with increasing generations.
• Thousands of SNVs, including 44 non-synonymous mutations, accumulated during sequential reprogramming.
• Accumulated SNVs were identified as the cause for the gradual reduction in all-iPSC mouse viability.
• Discovered heterogeneity in pluripotent stem cells regarding unique copy-number alterations (CNAs) that disappear upon differentiation.

Conclusions:

• Sequential reprogramming and serial generation of mice from iPSCs lead to the accumulation of detrimental somatic mutations.
• Accumulated SNVs significantly reduce the viability and developmental potential of mice derived from serially reprogrammed iPSCs.
• Pluripotent stem cells exhibit inherent heterogeneity in copy-number alterations, which are lost during differentiation.